diff options
Diffstat (limited to 'mm/vma.c')
| -rw-r--r-- | mm/vma.c | 3156 |
1 files changed, 3156 insertions, 0 deletions
diff --git a/mm/vma.c b/mm/vma.c new file mode 100644 index 000000000000..fef67a66a095 --- /dev/null +++ b/mm/vma.c @@ -0,0 +1,3156 @@ +// SPDX-License-Identifier: GPL-2.0-or-later + +/* + * VMA-specific functions. + */ + +#include "vma_internal.h" +#include "vma.h" + +struct mmap_state { + struct mm_struct *mm; + struct vma_iterator *vmi; + + unsigned long addr; + unsigned long end; + pgoff_t pgoff; + unsigned long pglen; + unsigned long flags; + struct file *file; + pgprot_t page_prot; + + /* User-defined fields, perhaps updated by .mmap_prepare(). */ + const struct vm_operations_struct *vm_ops; + void *vm_private_data; + + unsigned long charged; + + struct vm_area_struct *prev; + struct vm_area_struct *next; + + /* Unmapping state. */ + struct vma_munmap_struct vms; + struct ma_state mas_detach; + struct maple_tree mt_detach; +}; + +#define MMAP_STATE(name, mm_, vmi_, addr_, len_, pgoff_, flags_, file_) \ + struct mmap_state name = { \ + .mm = mm_, \ + .vmi = vmi_, \ + .addr = addr_, \ + .end = (addr_) + (len_), \ + .pgoff = pgoff_, \ + .pglen = PHYS_PFN(len_), \ + .flags = flags_, \ + .file = file_, \ + .page_prot = vm_get_page_prot(flags_), \ + } + +#define VMG_MMAP_STATE(name, map_, vma_) \ + struct vma_merge_struct name = { \ + .mm = (map_)->mm, \ + .vmi = (map_)->vmi, \ + .start = (map_)->addr, \ + .end = (map_)->end, \ + .flags = (map_)->flags, \ + .pgoff = (map_)->pgoff, \ + .file = (map_)->file, \ + .prev = (map_)->prev, \ + .middle = vma_, \ + .next = (vma_) ? NULL : (map_)->next, \ + .state = VMA_MERGE_START, \ + } + +/* + * If, at any point, the VMA had unCoW'd mappings from parents, it will maintain + * more than one anon_vma_chain connecting it to more than one anon_vma. A merge + * would mean a wider range of folios sharing the root anon_vma lock, and thus + * potential lock contention, we do not wish to encourage merging such that this + * scales to a problem. + */ +static bool vma_had_uncowed_parents(struct vm_area_struct *vma) +{ + /* + * The list_is_singular() test is to avoid merging VMA cloned from + * parents. This can improve scalability caused by anon_vma lock. + */ + return vma && vma->anon_vma && !list_is_singular(&vma->anon_vma_chain); +} + +static inline bool is_mergeable_vma(struct vma_merge_struct *vmg, bool merge_next) +{ + struct vm_area_struct *vma = merge_next ? vmg->next : vmg->prev; + + if (!mpol_equal(vmg->policy, vma_policy(vma))) + return false; + /* + * VM_SOFTDIRTY should not prevent from VMA merging, if we + * match the flags but dirty bit -- the caller should mark + * merged VMA as dirty. If dirty bit won't be excluded from + * comparison, we increase pressure on the memory system forcing + * the kernel to generate new VMAs when old one could be + * extended instead. + */ + if ((vma->vm_flags ^ vmg->flags) & ~VM_SOFTDIRTY) + return false; + if (vma->vm_file != vmg->file) + return false; + if (!is_mergeable_vm_userfaultfd_ctx(vma, vmg->uffd_ctx)) + return false; + if (!anon_vma_name_eq(anon_vma_name(vma), vmg->anon_name)) + return false; + return true; +} + +static bool is_mergeable_anon_vma(struct vma_merge_struct *vmg, bool merge_next) +{ + struct vm_area_struct *tgt = merge_next ? vmg->next : vmg->prev; + struct vm_area_struct *src = vmg->middle; /* exisitng merge case. */ + struct anon_vma *tgt_anon = tgt->anon_vma; + struct anon_vma *src_anon = vmg->anon_vma; + + /* + * We _can_ have !src, vmg->anon_vma via copy_vma(). In this instance we + * will remove the existing VMA's anon_vma's so there's no scalability + * concerns. + */ + VM_WARN_ON(src && src_anon != src->anon_vma); + + /* Case 1 - we will dup_anon_vma() from src into tgt. */ + if (!tgt_anon && src_anon) + return !vma_had_uncowed_parents(src); + /* Case 2 - we will simply use tgt's anon_vma. */ + if (tgt_anon && !src_anon) + return !vma_had_uncowed_parents(tgt); + /* Case 3 - the anon_vma's are already shared. */ + return src_anon == tgt_anon; +} + +/* + * init_multi_vma_prep() - Initializer for struct vma_prepare + * @vp: The vma_prepare struct + * @vma: The vma that will be altered once locked + * @vmg: The merge state that will be used to determine adjustment and VMA + * removal. + */ +static void init_multi_vma_prep(struct vma_prepare *vp, + struct vm_area_struct *vma, + struct vma_merge_struct *vmg) +{ + struct vm_area_struct *adjust; + struct vm_area_struct **remove = &vp->remove; + + memset(vp, 0, sizeof(struct vma_prepare)); + vp->vma = vma; + vp->anon_vma = vma->anon_vma; + + if (vmg && vmg->__remove_middle) { + *remove = vmg->middle; + remove = &vp->remove2; + } + if (vmg && vmg->__remove_next) + *remove = vmg->next; + + if (vmg && vmg->__adjust_middle_start) + adjust = vmg->middle; + else if (vmg && vmg->__adjust_next_start) + adjust = vmg->next; + else + adjust = NULL; + + vp->adj_next = adjust; + if (!vp->anon_vma && adjust) + vp->anon_vma = adjust->anon_vma; + + VM_WARN_ON(vp->anon_vma && adjust && adjust->anon_vma && + vp->anon_vma != adjust->anon_vma); + + vp->file = vma->vm_file; + if (vp->file) + vp->mapping = vma->vm_file->f_mapping; + + if (vmg && vmg->skip_vma_uprobe) + vp->skip_vma_uprobe = true; +} + +/* + * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff) + * in front of (at a lower virtual address and file offset than) the vma. + * + * We cannot merge two vmas if they have differently assigned (non-NULL) + * anon_vmas, nor if same anon_vma is assigned but offsets incompatible. + * + * We don't check here for the merged mmap wrapping around the end of pagecache + * indices (16TB on ia32) because do_mmap() does not permit mmap's which + * wrap, nor mmaps which cover the final page at index -1UL. + * + * We assume the vma may be removed as part of the merge. + */ +static bool can_vma_merge_before(struct vma_merge_struct *vmg) +{ + pgoff_t pglen = PHYS_PFN(vmg->end - vmg->start); + + if (is_mergeable_vma(vmg, /* merge_next = */ true) && + is_mergeable_anon_vma(vmg, /* merge_next = */ true)) { + if (vmg->next->vm_pgoff == vmg->pgoff + pglen) + return true; + } + + return false; +} + +/* + * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff) + * beyond (at a higher virtual address and file offset than) the vma. + * + * We cannot merge two vmas if they have differently assigned (non-NULL) + * anon_vmas, nor if same anon_vma is assigned but offsets incompatible. + * + * We assume that vma is not removed as part of the merge. + */ +static bool can_vma_merge_after(struct vma_merge_struct *vmg) +{ + if (is_mergeable_vma(vmg, /* merge_next = */ false) && + is_mergeable_anon_vma(vmg, /* merge_next = */ false)) { + if (vmg->prev->vm_pgoff + vma_pages(vmg->prev) == vmg->pgoff) + return true; + } + return false; +} + +static void __vma_link_file(struct vm_area_struct *vma, + struct address_space *mapping) +{ + if (vma_is_shared_maywrite(vma)) + mapping_allow_writable(mapping); + + flush_dcache_mmap_lock(mapping); + vma_interval_tree_insert(vma, &mapping->i_mmap); + flush_dcache_mmap_unlock(mapping); +} + +/* + * Requires inode->i_mapping->i_mmap_rwsem + */ +static void __remove_shared_vm_struct(struct vm_area_struct *vma, + struct address_space *mapping) +{ + if (vma_is_shared_maywrite(vma)) + mapping_unmap_writable(mapping); + + flush_dcache_mmap_lock(mapping); + vma_interval_tree_remove(vma, &mapping->i_mmap); + flush_dcache_mmap_unlock(mapping); +} + +/* + * vma has some anon_vma assigned, and is already inserted on that + * anon_vma's interval trees. + * + * Before updating the vma's vm_start / vm_end / vm_pgoff fields, the + * vma must be removed from the anon_vma's interval trees using + * anon_vma_interval_tree_pre_update_vma(). + * + * After the update, the vma will be reinserted using + * anon_vma_interval_tree_post_update_vma(). + * + * The entire update must be protected by exclusive mmap_lock and by + * the root anon_vma's mutex. + */ +static void +anon_vma_interval_tree_pre_update_vma(struct vm_area_struct *vma) +{ + struct anon_vma_chain *avc; + + list_for_each_entry(avc, &vma->anon_vma_chain, same_vma) + anon_vma_interval_tree_remove(avc, &avc->anon_vma->rb_root); +} + +static void +anon_vma_interval_tree_post_update_vma(struct vm_area_struct *vma) +{ + struct anon_vma_chain *avc; + + list_for_each_entry(avc, &vma->anon_vma_chain, same_vma) + anon_vma_interval_tree_insert(avc, &avc->anon_vma->rb_root); +} + +/* + * vma_prepare() - Helper function for handling locking VMAs prior to altering + * @vp: The initialized vma_prepare struct + */ +static void vma_prepare(struct vma_prepare *vp) +{ + if (vp->file) { + uprobe_munmap(vp->vma, vp->vma->vm_start, vp->vma->vm_end); + + if (vp->adj_next) + uprobe_munmap(vp->adj_next, vp->adj_next->vm_start, + vp->adj_next->vm_end); + + i_mmap_lock_write(vp->mapping); + if (vp->insert && vp->insert->vm_file) { + /* + * Put into interval tree now, so instantiated pages + * are visible to arm/parisc __flush_dcache_page + * throughout; but we cannot insert into address + * space until vma start or end is updated. + */ + __vma_link_file(vp->insert, + vp->insert->vm_file->f_mapping); + } + } + + if (vp->anon_vma) { + anon_vma_lock_write(vp->anon_vma); + anon_vma_interval_tree_pre_update_vma(vp->vma); + if (vp->adj_next) + anon_vma_interval_tree_pre_update_vma(vp->adj_next); + } + + if (vp->file) { + flush_dcache_mmap_lock(vp->mapping); + vma_interval_tree_remove(vp->vma, &vp->mapping->i_mmap); + if (vp->adj_next) + vma_interval_tree_remove(vp->adj_next, + &vp->mapping->i_mmap); + } + +} + +/* + * vma_complete- Helper function for handling the unlocking after altering VMAs, + * or for inserting a VMA. + * + * @vp: The vma_prepare struct + * @vmi: The vma iterator + * @mm: The mm_struct + */ +static void vma_complete(struct vma_prepare *vp, struct vma_iterator *vmi, + struct mm_struct *mm) +{ + if (vp->file) { + if (vp->adj_next) + vma_interval_tree_insert(vp->adj_next, + &vp->mapping->i_mmap); + vma_interval_tree_insert(vp->vma, &vp->mapping->i_mmap); + flush_dcache_mmap_unlock(vp->mapping); + } + + if (vp->remove && vp->file) { + __remove_shared_vm_struct(vp->remove, vp->mapping); + if (vp->remove2) + __remove_shared_vm_struct(vp->remove2, vp->mapping); + } else if (vp->insert) { + /* + * split_vma has split insert from vma, and needs + * us to insert it before dropping the locks + * (it may either follow vma or precede it). + */ + vma_iter_store_new(vmi, vp->insert); + mm->map_count++; + } + + if (vp->anon_vma) { + anon_vma_interval_tree_post_update_vma(vp->vma); + if (vp->adj_next) + anon_vma_interval_tree_post_update_vma(vp->adj_next); + anon_vma_unlock_write(vp->anon_vma); + } + + if (vp->file) { + i_mmap_unlock_write(vp->mapping); + + if (!vp->skip_vma_uprobe) { + uprobe_mmap(vp->vma); + + if (vp->adj_next) + uprobe_mmap(vp->adj_next); + } + } + + if (vp->remove) { +again: + vma_mark_detached(vp->remove); + if (vp->file) { + uprobe_munmap(vp->remove, vp->remove->vm_start, + vp->remove->vm_end); + fput(vp->file); + } + if (vp->remove->anon_vma) + anon_vma_merge(vp->vma, vp->remove); + mm->map_count--; + mpol_put(vma_policy(vp->remove)); + if (!vp->remove2) + WARN_ON_ONCE(vp->vma->vm_end < vp->remove->vm_end); + vm_area_free(vp->remove); + + /* + * In mprotect's case 6 (see comments on vma_merge), + * we are removing both mid and next vmas + */ + if (vp->remove2) { + vp->remove = vp->remove2; + vp->remove2 = NULL; + goto again; + } + } + if (vp->insert && vp->file) + uprobe_mmap(vp->insert); +} + +/* + * init_vma_prep() - Initializer wrapper for vma_prepare struct + * @vp: The vma_prepare struct + * @vma: The vma that will be altered once locked + */ +static void init_vma_prep(struct vma_prepare *vp, struct vm_area_struct *vma) +{ + init_multi_vma_prep(vp, vma, NULL); +} + +/* + * Can the proposed VMA be merged with the left (previous) VMA taking into + * account the start position of the proposed range. + */ +static bool can_vma_merge_left(struct vma_merge_struct *vmg) + +{ + return vmg->prev && vmg->prev->vm_end == vmg->start && + can_vma_merge_after(vmg); +} + +/* + * Can the proposed VMA be merged with the right (next) VMA taking into + * account the end position of the proposed range. + * + * In addition, if we can merge with the left VMA, ensure that left and right + * anon_vma's are also compatible. + */ +static bool can_vma_merge_right(struct vma_merge_struct *vmg, + bool can_merge_left) +{ + struct vm_area_struct *next = vmg->next; + struct vm_area_struct *prev; + + if (!next || vmg->end != next->vm_start || !can_vma_merge_before(vmg)) + return false; + + if (!can_merge_left) + return true; + + /* + * If we can merge with prev (left) and next (right), indicating that + * each VMA's anon_vma is compatible with the proposed anon_vma, this + * does not mean prev and next are compatible with EACH OTHER. + * + * We therefore check this in addition to mergeability to either side. + */ + prev = vmg->prev; + return !prev->anon_vma || !next->anon_vma || + prev->anon_vma == next->anon_vma; +} + +/* + * Close a vm structure and free it. + */ +void remove_vma(struct vm_area_struct *vma) +{ + might_sleep(); + vma_close(vma); + if (vma->vm_file) + fput(vma->vm_file); + mpol_put(vma_policy(vma)); + vm_area_free(vma); +} + +/* + * Get rid of page table information in the indicated region. + * + * Called with the mm semaphore held. + */ +void unmap_region(struct ma_state *mas, struct vm_area_struct *vma, + struct vm_area_struct *prev, struct vm_area_struct *next) +{ + struct mm_struct *mm = vma->vm_mm; + struct mmu_gather tlb; + + tlb_gather_mmu(&tlb, mm); + update_hiwater_rss(mm); + unmap_vmas(&tlb, mas, vma, vma->vm_start, vma->vm_end, vma->vm_end, + /* mm_wr_locked = */ true); + mas_set(mas, vma->vm_end); + free_pgtables(&tlb, mas, vma, prev ? prev->vm_end : FIRST_USER_ADDRESS, + next ? next->vm_start : USER_PGTABLES_CEILING, + /* mm_wr_locked = */ true); + tlb_finish_mmu(&tlb); +} + +/* + * __split_vma() bypasses sysctl_max_map_count checking. We use this where it + * has already been checked or doesn't make sense to fail. + * VMA Iterator will point to the original VMA. + */ +static __must_check int +__split_vma(struct vma_iterator *vmi, struct vm_area_struct *vma, + unsigned long addr, int new_below) +{ + struct vma_prepare vp; + struct vm_area_struct *new; + int err; + + WARN_ON(vma->vm_start >= addr); + WARN_ON(vma->vm_end <= addr); + + if (vma->vm_ops && vma->vm_ops->may_split) { + err = vma->vm_ops->may_split(vma, addr); + if (err) + return err; + } + + new = vm_area_dup(vma); + if (!new) + return -ENOMEM; + + if (new_below) { + new->vm_end = addr; + } else { + new->vm_start = addr; + new->vm_pgoff += ((addr - vma->vm_start) >> PAGE_SHIFT); + } + + err = -ENOMEM; + vma_iter_config(vmi, new->vm_start, new->vm_end); + if (vma_iter_prealloc(vmi, new)) + goto out_free_vma; + + err = vma_dup_policy(vma, new); + if (err) + goto out_free_vmi; + + err = anon_vma_clone(new, vma); + if (err) + goto out_free_mpol; + + if (new->vm_file) + get_file(new->vm_file); + + if (new->vm_ops && new->vm_ops->open) + new->vm_ops->open(new); + + vma_start_write(vma); + vma_start_write(new); + + init_vma_prep(&vp, vma); + vp.insert = new; + vma_prepare(&vp); + + /* + * Get rid of huge pages and shared page tables straddling the split + * boundary. + */ + vma_adjust_trans_huge(vma, vma->vm_start, addr, NULL); + if (is_vm_hugetlb_page(vma)) + hugetlb_split(vma, addr); + + if (new_below) { + vma->vm_start = addr; + vma->vm_pgoff += (addr - new->vm_start) >> PAGE_SHIFT; + } else { + vma->vm_end = addr; + } + + /* vma_complete stores the new vma */ + vma_complete(&vp, vmi, vma->vm_mm); + validate_mm(vma->vm_mm); + + /* Success. */ + if (new_below) + vma_next(vmi); + else + vma_prev(vmi); + + return 0; + +out_free_mpol: + mpol_put(vma_policy(new)); +out_free_vmi: + vma_iter_free(vmi); +out_free_vma: + vm_area_free(new); + return err; +} + +/* + * Split a vma into two pieces at address 'addr', a new vma is allocated + * either for the first part or the tail. + */ +static int split_vma(struct vma_iterator *vmi, struct vm_area_struct *vma, + unsigned long addr, int new_below) +{ + if (vma->vm_mm->map_count >= sysctl_max_map_count) + return -ENOMEM; + + return __split_vma(vmi, vma, addr, new_below); +} + +/* + * dup_anon_vma() - Helper function to duplicate anon_vma on VMA merge in the + * instance that the destination VMA has no anon_vma but the source does. + * + * @dst: The destination VMA + * @src: The source VMA + * @dup: Pointer to the destination VMA when successful. + * + * Returns: 0 on success. + */ +static int dup_anon_vma(struct vm_area_struct *dst, + struct vm_area_struct *src, struct vm_area_struct **dup) +{ + /* + * There are three cases to consider for correctly propagating + * anon_vma's on merge. + * + * The first is trivial - neither VMA has anon_vma, we need not do + * anything. + * + * The second where both have anon_vma is also a no-op, as they must + * then be the same, so there is simply nothing to copy. + * + * Here we cover the third - if the destination VMA has no anon_vma, + * that is it is unfaulted, we need to ensure that the newly merged + * range is referenced by the anon_vma's of the source. + */ + if (src->anon_vma && !dst->anon_vma) { + int ret; + + vma_assert_write_locked(dst); + dst->anon_vma = src->anon_vma; + ret = anon_vma_clone(dst, src); + if (ret) + return ret; + + *dup = dst; + } + + return 0; +} + +#ifdef CONFIG_DEBUG_VM_MAPLE_TREE +void validate_mm(struct mm_struct *mm) +{ + int bug = 0; + int i = 0; + struct vm_area_struct *vma; + VMA_ITERATOR(vmi, mm, 0); + + mt_validate(&mm->mm_mt); + for_each_vma(vmi, vma) { +#ifdef CONFIG_DEBUG_VM_RB + struct anon_vma *anon_vma = vma->anon_vma; + struct anon_vma_chain *avc; +#endif + unsigned long vmi_start, vmi_end; + bool warn = 0; + + vmi_start = vma_iter_addr(&vmi); + vmi_end = vma_iter_end(&vmi); + if (VM_WARN_ON_ONCE_MM(vma->vm_end != vmi_end, mm)) + warn = 1; + + if (VM_WARN_ON_ONCE_MM(vma->vm_start != vmi_start, mm)) + warn = 1; + + if (warn) { + pr_emerg("issue in %s\n", current->comm); + dump_stack(); + dump_vma(vma); + pr_emerg("tree range: %px start %lx end %lx\n", vma, + vmi_start, vmi_end - 1); + vma_iter_dump_tree(&vmi); + } + +#ifdef CONFIG_DEBUG_VM_RB + if (anon_vma) { + anon_vma_lock_read(anon_vma); + list_for_each_entry(avc, &vma->anon_vma_chain, same_vma) + anon_vma_interval_tree_verify(avc); + anon_vma_unlock_read(anon_vma); + } +#endif + /* Check for a infinite loop */ + if (++i > mm->map_count + 10) { + i = -1; + break; + } + } + if (i != mm->map_count) { + pr_emerg("map_count %d vma iterator %d\n", mm->map_count, i); + bug = 1; + } + VM_BUG_ON_MM(bug, mm); +} +#endif /* CONFIG_DEBUG_VM_MAPLE_TREE */ + +/* + * Based on the vmg flag indicating whether we need to adjust the vm_start field + * for the middle or next VMA, we calculate what the range of the newly adjusted + * VMA ought to be, and set the VMA's range accordingly. + */ +static void vmg_adjust_set_range(struct vma_merge_struct *vmg) +{ + struct vm_area_struct *adjust; + pgoff_t pgoff; + + if (vmg->__adjust_middle_start) { + adjust = vmg->middle; + pgoff = adjust->vm_pgoff + PHYS_PFN(vmg->end - adjust->vm_start); + } else if (vmg->__adjust_next_start) { + adjust = vmg->next; + pgoff = adjust->vm_pgoff - PHYS_PFN(adjust->vm_start - vmg->end); + } else { + return; + } + + vma_set_range(adjust, vmg->end, adjust->vm_end, pgoff); +} + +/* + * Actually perform the VMA merge operation. + * + * IMPORTANT: We guarantee that, should vmg->give_up_on_oom is set, to not + * modify any VMAs or cause inconsistent state should an OOM condition arise. + * + * Returns 0 on success, or an error value on failure. + */ +static int commit_merge(struct vma_merge_struct *vmg) +{ + struct vm_area_struct *vma; + struct vma_prepare vp; + + if (vmg->__adjust_next_start) { + /* We manipulate middle and adjust next, which is the target. */ + vma = vmg->middle; + vma_iter_config(vmg->vmi, vmg->end, vmg->next->vm_end); + } else { + vma = vmg->target; + /* Note: vma iterator must be pointing to 'start'. */ + vma_iter_config(vmg->vmi, vmg->start, vmg->end); + } + + init_multi_vma_prep(&vp, vma, vmg); + + /* + * If vmg->give_up_on_oom is set, we're safe, because we don't actually + * manipulate any VMAs until we succeed at preallocation. + * + * Past this point, we will not return an error. + */ + if (vma_iter_prealloc(vmg->vmi, vma)) + return -ENOMEM; + + vma_prepare(&vp); + /* + * THP pages may need to do additional splits if we increase + * middle->vm_start. + */ + vma_adjust_trans_huge(vma, vmg->start, vmg->end, + vmg->__adjust_middle_start ? vmg->middle : NULL); + vma_set_range(vma, vmg->start, vmg->end, vmg->pgoff); + vmg_adjust_set_range(vmg); + vma_iter_store_overwrite(vmg->vmi, vmg->target); + + vma_complete(&vp, vmg->vmi, vma->vm_mm); + + return 0; +} + +/* We can only remove VMAs when merging if they do not have a close hook. */ +static bool can_merge_remove_vma(struct vm_area_struct *vma) +{ + return !vma->vm_ops || !vma->vm_ops->close; +} + +/* + * vma_merge_existing_range - Attempt to merge VMAs based on a VMA having its + * attributes modified. + * + * @vmg: Describes the modifications being made to a VMA and associated + * metadata. + * + * When the attributes of a range within a VMA change, then it might be possible + * for immediately adjacent VMAs to be merged into that VMA due to having + * identical properties. + * + * This function checks for the existence of any such mergeable VMAs and updates + * the maple tree describing the @vmg->middle->vm_mm address space to account + * for this, as well as any VMAs shrunk/expanded/deleted as a result of this + * merge. + * + * As part of this operation, if a merge occurs, the @vmg object will have its + * vma, start, end, and pgoff fields modified to execute the merge. Subsequent + * calls to this function should reset these fields. + * + * Returns: The merged VMA if merge succeeds, or NULL otherwise. + * + * ASSUMPTIONS: + * - The caller must assign the VMA to be modifed to @vmg->middle. + * - The caller must have set @vmg->prev to the previous VMA, if there is one. + * - The caller must not set @vmg->next, as we determine this. + * - The caller must hold a WRITE lock on the mm_struct->mmap_lock. + * - vmi must be positioned within [@vmg->middle->vm_start, @vmg->middle->vm_end). + */ +static __must_check struct vm_area_struct *vma_merge_existing_range( + struct vma_merge_struct *vmg) +{ + struct vm_area_struct *middle = vmg->middle; + struct vm_area_struct *prev = vmg->prev; + struct vm_area_struct *next; + struct vm_area_struct *anon_dup = NULL; + unsigned long start = vmg->start; + unsigned long end = vmg->end; + bool left_side = middle && start == middle->vm_start; + bool right_side = middle && end == middle->vm_end; + int err = 0; + bool merge_left, merge_right, merge_both; + + mmap_assert_write_locked(vmg->mm); + VM_WARN_ON_VMG(!middle, vmg); /* We are modifying a VMA, so caller must specify. */ + VM_WARN_ON_VMG(vmg->next, vmg); /* We set this. */ + VM_WARN_ON_VMG(prev && start <= prev->vm_start, vmg); + VM_WARN_ON_VMG(start >= end, vmg); + + /* + * If middle == prev, then we are offset into a VMA. Otherwise, if we are + * not, we must span a portion of the VMA. + */ + VM_WARN_ON_VMG(middle && + ((middle != prev && vmg->start != middle->vm_start) || + vmg->end > middle->vm_end), vmg); + /* The vmi must be positioned within vmg->middle. */ + VM_WARN_ON_VMG(middle && + !(vma_iter_addr(vmg->vmi) >= middle->vm_start && + vma_iter_addr(vmg->vmi) < middle->vm_end), vmg); + + vmg->state = VMA_MERGE_NOMERGE; + + /* + * If a special mapping or if the range being modified is neither at the + * furthermost left or right side of the VMA, then we have no chance of + * merging and should abort. + */ + if (vmg->flags & VM_SPECIAL || (!left_side && !right_side)) + return NULL; + + if (left_side) + merge_left = can_vma_merge_left(vmg); + else + merge_left = false; + + if (right_side) { + next = vmg->next = vma_iter_next_range(vmg->vmi); + vma_iter_prev_range(vmg->vmi); + + merge_right = can_vma_merge_right(vmg, merge_left); + } else { + merge_right = false; + next = NULL; + } + + if (merge_left) /* If merging prev, position iterator there. */ + vma_prev(vmg->vmi); + else if (!merge_right) /* If we have nothing to merge, abort. */ + return NULL; + + merge_both = merge_left && merge_right; + /* If we span the entire VMA, a merge implies it will be deleted. */ + vmg->__remove_middle = left_side && right_side; + + /* + * If we need to remove middle in its entirety but are unable to do so, + * we have no sensible recourse but to abort the merge. + */ + if (vmg->__remove_middle && !can_merge_remove_vma(middle)) + return NULL; + + /* + * If we merge both VMAs, then next is also deleted. This implies + * merge_will_delete_vma also. + */ + vmg->__remove_next = merge_both; + + /* + * If we cannot delete next, then we can reduce the operation to merging + * prev and middle (thereby deleting middle). + */ + if (vmg->__remove_next && !can_merge_remove_vma(next)) { + vmg->__remove_next = false; + merge_right = false; + merge_both = false; + } + + /* No matter what happens, we will be adjusting middle. */ + vma_start_write(middle); + + if (merge_right) { + vma_start_write(next); + vmg->target = next; + } + + if (merge_left) { + vma_start_write(prev); + vmg->target = prev; + } + + if (merge_both) { + /* + * |<-------------------->| + * |-------********-------| + * prev middle next + * extend delete delete + */ + + vmg->start = prev->vm_start; + vmg->end = next->vm_end; + vmg->pgoff = prev->vm_pgoff; + + /* + * We already ensured anon_vma compatibility above, so now it's + * simply a case of, if prev has no anon_vma object, which of + * next or middle contains the anon_vma we must duplicate. + */ + err = dup_anon_vma(prev, next->anon_vma ? next : middle, + &anon_dup); + } else if (merge_left) { + /* + * |<------------>| OR + * |<----------------->| + * |-------************* + * prev middle + * extend shrink/delete + */ + + vmg->start = prev->vm_start; + vmg->pgoff = prev->vm_pgoff; + + if (!vmg->__remove_middle) + vmg->__adjust_middle_start = true; + + err = dup_anon_vma(prev, middle, &anon_dup); + } else { /* merge_right */ + /* + * |<------------->| OR + * |<----------------->| + * *************-------| + * middle next + * shrink/delete extend + */ + + pgoff_t pglen = PHYS_PFN(vmg->end - vmg->start); + + VM_WARN_ON_VMG(!merge_right, vmg); + /* If we are offset into a VMA, then prev must be middle. */ + VM_WARN_ON_VMG(vmg->start > middle->vm_start && prev && middle != prev, vmg); + + if (vmg->__remove_middle) { + vmg->end = next->vm_end; + vmg->pgoff = next->vm_pgoff - pglen; + } else { + /* We shrink middle and expand next. */ + vmg->__adjust_next_start = true; + vmg->start = middle->vm_start; + vmg->end = start; + vmg->pgoff = middle->vm_pgoff; + } + + err = dup_anon_vma(next, middle, &anon_dup); + } + + if (err || commit_merge(vmg)) + goto abort; + + khugepaged_enter_vma(vmg->target, vmg->flags); + vmg->state = VMA_MERGE_SUCCESS; + return vmg->target; + +abort: + vma_iter_set(vmg->vmi, start); + vma_iter_load(vmg->vmi); + + if (anon_dup) + unlink_anon_vmas(anon_dup); + + /* + * This means we have failed to clone anon_vma's correctly, but no + * actual changes to VMAs have occurred, so no harm no foul - if the + * user doesn't want this reported and instead just wants to give up on + * the merge, allow it. + */ + if (!vmg->give_up_on_oom) + vmg->state = VMA_MERGE_ERROR_NOMEM; + return NULL; +} + +/* + * vma_merge_new_range - Attempt to merge a new VMA into address space + * + * @vmg: Describes the VMA we are adding, in the range @vmg->start to @vmg->end + * (exclusive), which we try to merge with any adjacent VMAs if possible. + * + * We are about to add a VMA to the address space starting at @vmg->start and + * ending at @vmg->end. There are three different possible scenarios: + * + * 1. There is a VMA with identical properties immediately adjacent to the + * proposed new VMA [@vmg->start, @vmg->end) either before or after it - + * EXPAND that VMA: + * + * Proposed: |-----| or |-----| + * Existing: |----| |----| + * + * 2. There are VMAs with identical properties immediately adjacent to the + * proposed new VMA [@vmg->start, @vmg->end) both before AND after it - + * EXPAND the former and REMOVE the latter: + * + * Proposed: |-----| + * Existing: |----| |----| + * + * 3. There are no VMAs immediately adjacent to the proposed new VMA or those + * VMAs do not have identical attributes - NO MERGE POSSIBLE. + * + * In instances where we can merge, this function returns the expanded VMA which + * will have its range adjusted accordingly and the underlying maple tree also + * adjusted. + * + * Returns: In instances where no merge was possible, NULL. Otherwise, a pointer + * to the VMA we expanded. + * + * This function adjusts @vmg to provide @vmg->next if not already specified, + * and adjusts [@vmg->start, @vmg->end) to span the expanded range. + * + * ASSUMPTIONS: + * - The caller must hold a WRITE lock on the mm_struct->mmap_lock. + * - The caller must have determined that [@vmg->start, @vmg->end) is empty, + other than VMAs that will be unmapped should the operation succeed. + * - The caller must have specified the previous vma in @vmg->prev. + * - The caller must have specified the next vma in @vmg->next. + * - The caller must have positioned the vmi at or before the gap. + */ +struct vm_area_struct *vma_merge_new_range(struct vma_merge_struct *vmg) +{ + struct vm_area_struct *prev = vmg->prev; + struct vm_area_struct *next = vmg->next; + unsigned long end = vmg->end; + bool can_merge_left, can_merge_right; + + mmap_assert_write_locked(vmg->mm); + VM_WARN_ON_VMG(vmg->middle, vmg); + /* vmi must point at or before the gap. */ + VM_WARN_ON_VMG(vma_iter_addr(vmg->vmi) > end, vmg); + + vmg->state = VMA_MERGE_NOMERGE; + + /* Special VMAs are unmergeable, also if no prev/next. */ + if ((vmg->flags & VM_SPECIAL) || (!prev && !next)) + return NULL; + + can_merge_left = can_vma_merge_left(vmg); + can_merge_right = !vmg->just_expand && can_vma_merge_right(vmg, can_merge_left); + + /* If we can merge with the next VMA, adjust vmg accordingly. */ + if (can_merge_right) { + vmg->end = next->vm_end; + vmg->middle = next; + } + + /* If we can merge with the previous VMA, adjust vmg accordingly. */ + if (can_merge_left) { + vmg->start = prev->vm_start; + vmg->middle = prev; + vmg->pgoff = prev->vm_pgoff; + + /* + * If this merge would result in removal of the next VMA but we + * are not permitted to do so, reduce the operation to merging + * prev and vma. + */ + if (can_merge_right && !can_merge_remove_vma(next)) + vmg->end = end; + + /* In expand-only case we are already positioned at prev. */ + if (!vmg->just_expand) { + /* Equivalent to going to the previous range. */ + vma_prev(vmg->vmi); + } + } + + /* + * Now try to expand adjacent VMA(s). This takes care of removing the + * following VMA if we have VMAs on both sides. + */ + if (vmg->middle && !vma_expand(vmg)) { + khugepaged_enter_vma(vmg->middle, vmg->flags); + vmg->state = VMA_MERGE_SUCCESS; + return vmg->middle; + } + + return NULL; +} + +/* + * vma_expand - Expand an existing VMA + * + * @vmg: Describes a VMA expansion operation. + * + * Expand @vma to vmg->start and vmg->end. Can expand off the start and end. + * Will expand over vmg->next if it's different from vmg->middle and vmg->end == + * vmg->next->vm_end. Checking if the vmg->middle can expand and merge with + * vmg->next needs to be handled by the caller. + * + * Returns: 0 on success. + * + * ASSUMPTIONS: + * - The caller must hold a WRITE lock on vmg->middle->mm->mmap_lock. + * - The caller must have set @vmg->middle and @vmg->next. + */ +int vma_expand(struct vma_merge_struct *vmg) +{ + struct vm_area_struct *anon_dup = NULL; + bool remove_next = false; + struct vm_area_struct *middle = vmg->middle; + struct vm_area_struct *next = vmg->next; + + mmap_assert_write_locked(vmg->mm); + + vma_start_write(middle); + if (next && (middle != next) && (vmg->end == next->vm_end)) { + int ret; + + remove_next = true; + /* This should already have been checked by this point. */ + VM_WARN_ON_VMG(!can_merge_remove_vma(next), vmg); + vma_start_write(next); + /* + * In this case we don't report OOM, so vmg->give_up_on_mm is + * safe. + */ + ret = dup_anon_vma(middle, next, &anon_dup); + if (ret) + return ret; + } + + /* Not merging but overwriting any part of next is not handled. */ + VM_WARN_ON_VMG(next && !remove_next && + next != middle && vmg->end > next->vm_start, vmg); + /* Only handles expanding */ + VM_WARN_ON_VMG(middle->vm_start < vmg->start || + middle->vm_end > vmg->end, vmg); + + vmg->target = middle; + if (remove_next) + vmg->__remove_next = true; + + if (commit_merge(vmg)) + goto nomem; + + return 0; + +nomem: + if (anon_dup) + unlink_anon_vmas(anon_dup); + /* + * If the user requests that we just give upon OOM, we are safe to do so + * here, as commit merge provides this contract to us. Nothing has been + * changed - no harm no foul, just don't report it. + */ + if (!vmg->give_up_on_oom) + vmg->state = VMA_MERGE_ERROR_NOMEM; + return -ENOMEM; +} + +/* + * vma_shrink() - Reduce an existing VMAs memory area + * @vmi: The vma iterator + * @vma: The VMA to modify + * @start: The new start + * @end: The new end + * + * Returns: 0 on success, -ENOMEM otherwise + */ +int vma_shrink(struct vma_iterator *vmi, struct vm_area_struct *vma, + unsigned long start, unsigned long end, pgoff_t pgoff) +{ + struct vma_prepare vp; + + WARN_ON((vma->vm_start != start) && (vma->vm_end != end)); + + if (vma->vm_start < start) + vma_iter_config(vmi, vma->vm_start, start); + else + vma_iter_config(vmi, end, vma->vm_end); + + if (vma_iter_prealloc(vmi, NULL)) + return -ENOMEM; + + vma_start_write(vma); + + init_vma_prep(&vp, vma); + vma_prepare(&vp); + vma_adjust_trans_huge(vma, start, end, NULL); + + vma_iter_clear(vmi); + vma_set_range(vma, start, end, pgoff); + vma_complete(&vp, vmi, vma->vm_mm); + validate_mm(vma->vm_mm); + return 0; +} + +static inline void vms_clear_ptes(struct vma_munmap_struct *vms, + struct ma_state *mas_detach, bool mm_wr_locked) +{ + struct mmu_gather tlb; + + if (!vms->clear_ptes) /* Nothing to do */ + return; + + /* + * We can free page tables without write-locking mmap_lock because VMAs + * were isolated before we downgraded mmap_lock. + */ + mas_set(mas_detach, 1); + tlb_gather_mmu(&tlb, vms->vma->vm_mm); + update_hiwater_rss(vms->vma->vm_mm); + unmap_vmas(&tlb, mas_detach, vms->vma, vms->start, vms->end, + vms->vma_count, mm_wr_locked); + + mas_set(mas_detach, 1); + /* start and end may be different if there is no prev or next vma. */ + free_pgtables(&tlb, mas_detach, vms->vma, vms->unmap_start, + vms->unmap_end, mm_wr_locked); + tlb_finish_mmu(&tlb); + vms->clear_ptes = false; +} + +static void vms_clean_up_area(struct vma_munmap_struct *vms, + struct ma_state *mas_detach) +{ + struct vm_area_struct *vma; + + if (!vms->nr_pages) + return; + + vms_clear_ptes(vms, mas_detach, true); + mas_set(mas_detach, 0); + mas_for_each(mas_detach, vma, ULONG_MAX) + vma_close(vma); +} + +/* + * vms_complete_munmap_vmas() - Finish the munmap() operation + * @vms: The vma munmap struct + * @mas_detach: The maple state of the detached vmas + * + * This updates the mm_struct, unmaps the region, frees the resources + * used for the munmap() and may downgrade the lock - if requested. Everything + * needed to be done once the vma maple tree is updated. + */ +static void vms_complete_munmap_vmas(struct vma_munmap_struct *vms, + struct ma_state *mas_detach) +{ + struct vm_area_struct *vma; + struct mm_struct *mm; + + mm = current->mm; + mm->map_count -= vms->vma_count; + mm->locked_vm -= vms->locked_vm; + if (vms->unlock) + mmap_write_downgrade(mm); + + if (!vms->nr_pages) + return; + + vms_clear_ptes(vms, mas_detach, !vms->unlock); + /* Update high watermark before we lower total_vm */ + update_hiwater_vm(mm); + /* Stat accounting */ + WRITE_ONCE(mm->total_vm, READ_ONCE(mm->total_vm) - vms->nr_pages); + /* Paranoid bookkeeping */ + VM_WARN_ON(vms->exec_vm > mm->exec_vm); + VM_WARN_ON(vms->stack_vm > mm->stack_vm); + VM_WARN_ON(vms->data_vm > mm->data_vm); + mm->exec_vm -= vms->exec_vm; + mm->stack_vm -= vms->stack_vm; + mm->data_vm -= vms->data_vm; + + /* Remove and clean up vmas */ + mas_set(mas_detach, 0); + mas_for_each(mas_detach, vma, ULONG_MAX) + remove_vma(vma); + + vm_unacct_memory(vms->nr_accounted); + validate_mm(mm); + if (vms->unlock) + mmap_read_unlock(mm); + + __mt_destroy(mas_detach->tree); +} + +/* + * reattach_vmas() - Undo any munmap work and free resources + * @mas_detach: The maple state with the detached maple tree + * + * Reattach any detached vmas and free up the maple tree used to track the vmas. + */ +static void reattach_vmas(struct ma_state *mas_detach) +{ + struct vm_area_struct *vma; + + mas_set(mas_detach, 0); + mas_for_each(mas_detach, vma, ULONG_MAX) + vma_mark_attached(vma); + + __mt_destroy(mas_detach->tree); +} + +/* + * vms_gather_munmap_vmas() - Put all VMAs within a range into a maple tree + * for removal at a later date. Handles splitting first and last if necessary + * and marking the vmas as isolated. + * + * @vms: The vma munmap struct + * @mas_detach: The maple state tracking the detached tree + * + * Return: 0 on success, error otherwise + */ +static int vms_gather_munmap_vmas(struct vma_munmap_struct *vms, + struct ma_state *mas_detach) +{ + struct vm_area_struct *next = NULL; + int error; + + /* + * If we need to split any vma, do it now to save pain later. + * Does it split the first one? + */ + if (vms->start > vms->vma->vm_start) { + + /* + * Make sure that map_count on return from munmap() will + * not exceed its limit; but let map_count go just above + * its limit temporarily, to help free resources as expected. + */ + if (vms->end < vms->vma->vm_end && + vms->vma->vm_mm->map_count >= sysctl_max_map_count) { + error = -ENOMEM; + goto map_count_exceeded; + } + + /* Don't bother splitting the VMA if we can't unmap it anyway */ + if (!can_modify_vma(vms->vma)) { + error = -EPERM; + goto start_split_failed; + } + + error = __split_vma(vms->vmi, vms->vma, vms->start, 1); + if (error) + goto start_split_failed; + } + vms->prev = vma_prev(vms->vmi); + if (vms->prev) + vms->unmap_start = vms->prev->vm_end; + + /* + * Detach a range of VMAs from the mm. Using next as a temp variable as + * it is always overwritten. + */ + for_each_vma_range(*(vms->vmi), next, vms->end) { + long nrpages; + + if (!can_modify_vma(next)) { + error = -EPERM; + goto modify_vma_failed; + } + /* Does it split the end? */ + if (next->vm_end > vms->end) { + error = __split_vma(vms->vmi, next, vms->end, 0); + if (error) + goto end_split_failed; + } + vma_start_write(next); + mas_set(mas_detach, vms->vma_count++); + error = mas_store_gfp(mas_detach, next, GFP_KERNEL); + if (error) + goto munmap_gather_failed; + + vma_mark_detached(next); + nrpages = vma_pages(next); + + vms->nr_pages += nrpages; + if (next->vm_flags & VM_LOCKED) + vms->locked_vm += nrpages; + + if (next->vm_flags & VM_ACCOUNT) + vms->nr_accounted += nrpages; + + if (is_exec_mapping(next->vm_flags)) + vms->exec_vm += nrpages; + else if (is_stack_mapping(next->vm_flags)) + vms->stack_vm += nrpages; + else if (is_data_mapping(next->vm_flags)) + vms->data_vm += nrpages; + + if (vms->uf) { + /* + * If userfaultfd_unmap_prep returns an error the vmas + * will remain split, but userland will get a + * highly unexpected error anyway. This is no + * different than the case where the first of the two + * __split_vma fails, but we don't undo the first + * split, despite we could. This is unlikely enough + * failure that it's not worth optimizing it for. + */ + error = userfaultfd_unmap_prep(next, vms->start, + vms->end, vms->uf); + if (error) + goto userfaultfd_error; + } +#ifdef CONFIG_DEBUG_VM_MAPLE_TREE + BUG_ON(next->vm_start < vms->start); + BUG_ON(next->vm_start > vms->end); +#endif + } + + vms->next = vma_next(vms->vmi); + if (vms->next) + vms->unmap_end = vms->next->vm_start; + +#if defined(CONFIG_DEBUG_VM_MAPLE_TREE) + /* Make sure no VMAs are about to be lost. */ + { + MA_STATE(test, mas_detach->tree, 0, 0); + struct vm_area_struct *vma_mas, *vma_test; + int test_count = 0; + + vma_iter_set(vms->vmi, vms->start); + rcu_read_lock(); + vma_test = mas_find(&test, vms->vma_count - 1); + for_each_vma_range(*(vms->vmi), vma_mas, vms->end) { + BUG_ON(vma_mas != vma_test); + test_count++; + vma_test = mas_next(&test, vms->vma_count - 1); + } + rcu_read_unlock(); + BUG_ON(vms->vma_count != test_count); + } +#endif + + while (vma_iter_addr(vms->vmi) > vms->start) + vma_iter_prev_range(vms->vmi); + + vms->clear_ptes = true; + return 0; + +userfaultfd_error: +munmap_gather_failed: +end_split_failed: +modify_vma_failed: + reattach_vmas(mas_detach); +start_split_failed: +map_count_exceeded: + return error; +} + +/* + * init_vma_munmap() - Initializer wrapper for vma_munmap_struct + * @vms: The vma munmap struct + * @vmi: The vma iterator + * @vma: The first vm_area_struct to munmap + * @start: The aligned start address to munmap + * @end: The aligned end address to munmap + * @uf: The userfaultfd list_head + * @unlock: Unlock after the operation. Only unlocked on success + */ +static void init_vma_munmap(struct vma_munmap_struct *vms, + struct vma_iterator *vmi, struct vm_area_struct *vma, + unsigned long start, unsigned long end, struct list_head *uf, + bool unlock) +{ + vms->vmi = vmi; + vms->vma = vma; + if (vma) { + vms->start = start; + vms->end = end; + } else { + vms->start = vms->end = 0; + } + vms->unlock = unlock; + vms->uf = uf; + vms->vma_count = 0; + vms->nr_pages = vms->locked_vm = vms->nr_accounted = 0; + vms->exec_vm = vms->stack_vm = vms->data_vm = 0; + vms->unmap_start = FIRST_USER_ADDRESS; + vms->unmap_end = USER_PGTABLES_CEILING; + vms->clear_ptes = false; +} + +/* + * do_vmi_align_munmap() - munmap the aligned region from @start to @end. + * @vmi: The vma iterator + * @vma: The starting vm_area_struct + * @mm: The mm_struct + * @start: The aligned start address to munmap. + * @end: The aligned end address to munmap. + * @uf: The userfaultfd list_head + * @unlock: Set to true to drop the mmap_lock. unlocking only happens on + * success. + * + * Return: 0 on success and drops the lock if so directed, error and leaves the + * lock held otherwise. + */ +int do_vmi_align_munmap(struct vma_iterator *vmi, struct vm_area_struct *vma, + struct mm_struct *mm, unsigned long start, unsigned long end, + struct list_head *uf, bool unlock) +{ + struct maple_tree mt_detach; + MA_STATE(mas_detach, &mt_detach, 0, 0); + mt_init_flags(&mt_detach, vmi->mas.tree->ma_flags & MT_FLAGS_LOCK_MASK); + mt_on_stack(mt_detach); + struct vma_munmap_struct vms; + int error; + + init_vma_munmap(&vms, vmi, vma, start, end, uf, unlock); + error = vms_gather_munmap_vmas(&vms, &mas_detach); + if (error) + goto gather_failed; + + error = vma_iter_clear_gfp(vmi, start, end, GFP_KERNEL); + if (error) + goto clear_tree_failed; + + /* Point of no return */ + vms_complete_munmap_vmas(&vms, &mas_detach); + return 0; + +clear_tree_failed: + reattach_vmas(&mas_detach); +gather_failed: + validate_mm(mm); + return error; +} + +/* + * do_vmi_munmap() - munmap a given range. + * @vmi: The vma iterator + * @mm: The mm_struct + * @start: The start address to munmap + * @len: The length of the range to munmap + * @uf: The userfaultfd list_head + * @unlock: set to true if the user wants to drop the mmap_lock on success + * + * This function takes a @mas that is either pointing to the previous VMA or set + * to MA_START and sets it up to remove the mapping(s). The @len will be + * aligned. + * + * Return: 0 on success and drops the lock if so directed, error and leaves the + * lock held otherwise. + */ +int do_vmi_munmap(struct vma_iterator *vmi, struct mm_struct *mm, + unsigned long start, size_t len, struct list_head *uf, + bool unlock) +{ + unsigned long end; + struct vm_area_struct *vma; + + if ((offset_in_page(start)) || start > TASK_SIZE || len > TASK_SIZE-start) + return -EINVAL; + + end = start + PAGE_ALIGN(len); + if (end == start) + return -EINVAL; + + /* Find the first overlapping VMA */ + vma = vma_find(vmi, end); + if (!vma) { + if (unlock) + mmap_write_unlock(mm); + return 0; + } + + return do_vmi_align_munmap(vmi, vma, mm, start, end, uf, unlock); +} + +/* + * We are about to modify one or multiple of a VMA's flags, policy, userfaultfd + * context and anonymous VMA name within the range [start, end). + * + * As a result, we might be able to merge the newly modified VMA range with an + * adjacent VMA with identical properties. + * + * If no merge is possible and the range does not span the entirety of the VMA, + * we then need to split the VMA to accommodate the change. + * + * The function returns either the merged VMA, the original VMA if a split was + * required instead, or an error if the split failed. + */ +static struct vm_area_struct *vma_modify(struct vma_merge_struct *vmg) +{ + struct vm_area_struct *vma = vmg->middle; + unsigned long start = vmg->start; + unsigned long end = vmg->end; + struct vm_area_struct *merged; + + /* First, try to merge. */ + merged = vma_merge_existing_range(vmg); + if (merged) + return merged; + if (vmg_nomem(vmg)) + return ERR_PTR(-ENOMEM); + + /* + * Split can fail for reasons other than OOM, so if the user requests + * this it's probably a mistake. + */ + VM_WARN_ON(vmg->give_up_on_oom && + (vma->vm_start != start || vma->vm_end != end)); + + /* Split any preceding portion of the VMA. */ + if (vma->vm_start < start) { + int err = split_vma(vmg->vmi, vma, start, 1); + + if (err) + return ERR_PTR(err); + } + + /* Split any trailing portion of the VMA. */ + if (vma->vm_end > end) { + int err = split_vma(vmg->vmi, vma, end, 0); + + if (err) + return ERR_PTR(err); + } + + return vma; +} + +struct vm_area_struct *vma_modify_flags( + struct vma_iterator *vmi, struct vm_area_struct *prev, + struct vm_area_struct *vma, unsigned long start, unsigned long end, + unsigned long new_flags) +{ + VMG_VMA_STATE(vmg, vmi, prev, vma, start, end); + + vmg.flags = new_flags; + + return vma_modify(&vmg); +} + +struct vm_area_struct +*vma_modify_flags_name(struct vma_iterator *vmi, + struct vm_area_struct *prev, + struct vm_area_struct *vma, + unsigned long start, + unsigned long end, + unsigned long new_flags, + struct anon_vma_name *new_name) +{ + VMG_VMA_STATE(vmg, vmi, prev, vma, start, end); + + vmg.flags = new_flags; + vmg.anon_name = new_name; + + return vma_modify(&vmg); +} + +struct vm_area_struct +*vma_modify_policy(struct vma_iterator *vmi, + struct vm_area_struct *prev, + struct vm_area_struct *vma, + unsigned long start, unsigned long end, + struct mempolicy *new_pol) +{ + VMG_VMA_STATE(vmg, vmi, prev, vma, start, end); + + vmg.policy = new_pol; + + return vma_modify(&vmg); +} + +struct vm_area_struct +*vma_modify_flags_uffd(struct vma_iterator *vmi, + struct vm_area_struct *prev, + struct vm_area_struct *vma, + unsigned long start, unsigned long end, + unsigned long new_flags, + struct vm_userfaultfd_ctx new_ctx, + bool give_up_on_oom) +{ + VMG_VMA_STATE(vmg, vmi, prev, vma, start, end); + + vmg.flags = new_flags; + vmg.uffd_ctx = new_ctx; + if (give_up_on_oom) + vmg.give_up_on_oom = true; + + return vma_modify(&vmg); +} + +/* + * Expand vma by delta bytes, potentially merging with an immediately adjacent + * VMA with identical properties. + */ +struct vm_area_struct *vma_merge_extend(struct vma_iterator *vmi, + struct vm_area_struct *vma, + unsigned long delta) +{ + VMG_VMA_STATE(vmg, vmi, vma, vma, vma->vm_end, vma->vm_end + delta); + + vmg.next = vma_iter_next_rewind(vmi, NULL); + vmg.middle = NULL; /* We use the VMA to populate VMG fields only. */ + + return vma_merge_new_range(&vmg); +} + +void unlink_file_vma_batch_init(struct unlink_vma_file_batch *vb) +{ + vb->count = 0; +} + +static void unlink_file_vma_batch_process(struct unlink_vma_file_batch *vb) +{ + struct address_space *mapping; + int i; + + mapping = vb->vmas[0]->vm_file->f_mapping; + i_mmap_lock_write(mapping); + for (i = 0; i < vb->count; i++) { + VM_WARN_ON_ONCE(vb->vmas[i]->vm_file->f_mapping != mapping); + __remove_shared_vm_struct(vb->vmas[i], mapping); + } + i_mmap_unlock_write(mapping); + + unlink_file_vma_batch_init(vb); +} + +void unlink_file_vma_batch_add(struct unlink_vma_file_batch *vb, + struct vm_area_struct *vma) +{ + if (vma->vm_file == NULL) + return; + + if ((vb->count > 0 && vb->vmas[0]->vm_file != vma->vm_file) || + vb->count == ARRAY_SIZE(vb->vmas)) + unlink_file_vma_batch_process(vb); + + vb->vmas[vb->count] = vma; + vb->count++; +} + +void unlink_file_vma_batch_final(struct unlink_vma_file_batch *vb) +{ + if (vb->count > 0) + unlink_file_vma_batch_process(vb); +} + +/* + * Unlink a file-based vm structure from its interval tree, to hide + * vma from rmap and vmtruncate before freeing its page tables. + */ +void unlink_file_vma(struct vm_area_struct *vma) +{ + struct file *file = vma->vm_file; + + if (file) { + struct address_space *mapping = file->f_mapping; + + i_mmap_lock_write(mapping); + __remove_shared_vm_struct(vma, mapping); + i_mmap_unlock_write(mapping); + } +} + +void vma_link_file(struct vm_area_struct *vma) +{ + struct file *file = vma->vm_file; + struct address_space *mapping; + + if (file) { + mapping = file->f_mapping; + i_mmap_lock_write(mapping); + __vma_link_file(vma, mapping); + i_mmap_unlock_write(mapping); + } +} + +int vma_link(struct mm_struct *mm, struct vm_area_struct *vma) +{ + VMA_ITERATOR(vmi, mm, 0); + + vma_iter_config(&vmi, vma->vm_start, vma->vm_end); + if (vma_iter_prealloc(&vmi, vma)) + return -ENOMEM; + + vma_start_write(vma); + vma_iter_store_new(&vmi, vma); + vma_link_file(vma); + mm->map_count++; + validate_mm(mm); + return 0; +} + +/* + * Copy the vma structure to a new location in the same mm, + * prior to moving page table entries, to effect an mremap move. + */ +struct vm_area_struct *copy_vma(struct vm_area_struct **vmap, + unsigned long addr, unsigned long len, pgoff_t pgoff, + bool *need_rmap_locks) +{ + struct vm_area_struct *vma = *vmap; + unsigned long vma_start = vma->vm_start; + struct mm_struct *mm = vma->vm_mm; + struct vm_area_struct *new_vma; + bool faulted_in_anon_vma = true; + VMA_ITERATOR(vmi, mm, addr); + VMG_VMA_STATE(vmg, &vmi, NULL, vma, addr, addr + len); + + /* + * If anonymous vma has not yet been faulted, update new pgoff + * to match new location, to increase its chance of merging. + */ + if (unlikely(vma_is_anonymous(vma) && !vma->anon_vma)) { + pgoff = addr >> PAGE_SHIFT; + faulted_in_anon_vma = false; + } + + /* + * If the VMA we are copying might contain a uprobe PTE, ensure + * that we do not establish one upon merge. Otherwise, when mremap() + * moves page tables, it will orphan the newly created PTE. + */ + if (vma->vm_file) + vmg.skip_vma_uprobe = true; + + new_vma = find_vma_prev(mm, addr, &vmg.prev); + if (new_vma && new_vma->vm_start < addr + len) + return NULL; /* should never get here */ + + vmg.middle = NULL; /* New VMA range. */ + vmg.pgoff = pgoff; + vmg.next = vma_iter_next_rewind(&vmi, NULL); + new_vma = vma_merge_new_range(&vmg); + + if (new_vma) { + /* + * Source vma may have been merged into new_vma + */ + if (unlikely(vma_start >= new_vma->vm_start && + vma_start < new_vma->vm_end)) { + /* + * The only way we can get a vma_merge with + * self during an mremap is if the vma hasn't + * been faulted in yet and we were allowed to + * reset the dst vma->vm_pgoff to the + * destination address of the mremap to allow + * the merge to happen. mremap must change the + * vm_pgoff linearity between src and dst vmas + * (in turn preventing a vma_merge) to be + * safe. It is only safe to keep the vm_pgoff + * linear if there are no pages mapped yet. + */ + VM_BUG_ON_VMA(faulted_in_anon_vma, new_vma); + *vmap = vma = new_vma; + } + *need_rmap_locks = (new_vma->vm_pgoff <= vma->vm_pgoff); + } else { + new_vma = vm_area_dup(vma); + if (!new_vma) + goto out; + vma_set_range(new_vma, addr, addr + len, pgoff); + if (vma_dup_policy(vma, new_vma)) + goto out_free_vma; + if (anon_vma_clone(new_vma, vma)) + goto out_free_mempol; + if (new_vma->vm_file) + get_file(new_vma->vm_file); + if (new_vma->vm_ops && new_vma->vm_ops->open) + new_vma->vm_ops->open(new_vma); + if (vma_link(mm, new_vma)) + goto out_vma_link; + *need_rmap_locks = false; + } + return new_vma; + +out_vma_link: + fixup_hugetlb_reservations(new_vma); + vma_close(new_vma); + + if (new_vma->vm_file) + fput(new_vma->vm_file); + + unlink_anon_vmas(new_vma); +out_free_mempol: + mpol_put(vma_policy(new_vma)); +out_free_vma: + vm_area_free(new_vma); +out: + return NULL; +} + +/* + * Rough compatibility check to quickly see if it's even worth looking + * at sharing an anon_vma. + * + * They need to have the same vm_file, and the flags can only differ + * in things that mprotect may change. + * + * NOTE! The fact that we share an anon_vma doesn't _have_ to mean that + * we can merge the two vma's. For example, we refuse to merge a vma if + * there is a vm_ops->close() function, because that indicates that the + * driver is doing some kind of reference counting. But that doesn't + * really matter for the anon_vma sharing case. + */ +static int anon_vma_compatible(struct vm_area_struct *a, struct vm_area_struct *b) +{ + return a->vm_end == b->vm_start && + mpol_equal(vma_policy(a), vma_policy(b)) && + a->vm_file == b->vm_file && + !((a->vm_flags ^ b->vm_flags) & ~(VM_ACCESS_FLAGS | VM_SOFTDIRTY)) && + b->vm_pgoff == a->vm_pgoff + ((b->vm_start - a->vm_start) >> PAGE_SHIFT); +} + +/* + * Do some basic sanity checking to see if we can re-use the anon_vma + * from 'old'. The 'a'/'b' vma's are in VM order - one of them will be + * the same as 'old', the other will be the new one that is trying + * to share the anon_vma. + * + * NOTE! This runs with mmap_lock held for reading, so it is possible that + * the anon_vma of 'old' is concurrently in the process of being set up + * by another page fault trying to merge _that_. But that's ok: if it + * is being set up, that automatically means that it will be a singleton + * acceptable for merging, so we can do all of this optimistically. But + * we do that READ_ONCE() to make sure that we never re-load the pointer. + * + * IOW: that the "list_is_singular()" test on the anon_vma_chain only + * matters for the 'stable anon_vma' case (ie the thing we want to avoid + * is to return an anon_vma that is "complex" due to having gone through + * a fork). + * + * We also make sure that the two vma's are compatible (adjacent, + * and with the same memory policies). That's all stable, even with just + * a read lock on the mmap_lock. + */ +static struct anon_vma *reusable_anon_vma(struct vm_area_struct *old, + struct vm_area_struct *a, + struct vm_area_struct *b) +{ + if (anon_vma_compatible(a, b)) { + struct anon_vma *anon_vma = READ_ONCE(old->anon_vma); + + if (anon_vma && list_is_singular(&old->anon_vma_chain)) + return anon_vma; + } + return NULL; +} + +/* + * find_mergeable_anon_vma is used by anon_vma_prepare, to check + * neighbouring vmas for a suitable anon_vma, before it goes off + * to allocate a new anon_vma. It checks because a repetitive + * sequence of mprotects and faults may otherwise lead to distinct + * anon_vmas being allocated, preventing vma merge in subsequent + * mprotect. + */ +struct anon_vma *find_mergeable_anon_vma(struct vm_area_struct *vma) +{ + struct anon_vma *anon_vma = NULL; + struct vm_area_struct *prev, *next; + VMA_ITERATOR(vmi, vma->vm_mm, vma->vm_end); + + /* Try next first. */ + next = vma_iter_load(&vmi); + if (next) { + anon_vma = reusable_anon_vma(next, vma, next); + if (anon_vma) + return anon_vma; + } + + prev = vma_prev(&vmi); + VM_BUG_ON_VMA(prev != vma, vma); + prev = vma_prev(&vmi); + /* Try prev next. */ + if (prev) + anon_vma = reusable_anon_vma(prev, prev, vma); + + /* + * We might reach here with anon_vma == NULL if we can't find + * any reusable anon_vma. + * There's no absolute need to look only at touching neighbours: + * we could search further afield for "compatible" anon_vmas. + * But it would probably just be a waste of time searching, + * or lead to too many vmas hanging off the same anon_vma. + * We're trying to allow mprotect remerging later on, + * not trying to minimize memory used for anon_vmas. + */ + return anon_vma; +} + +static bool vm_ops_needs_writenotify(const struct vm_operations_struct *vm_ops) +{ + return vm_ops && (vm_ops->page_mkwrite || vm_ops->pfn_mkwrite); +} + +static bool vma_is_shared_writable(struct vm_area_struct *vma) +{ + return (vma->vm_flags & (VM_WRITE | VM_SHARED)) == + (VM_WRITE | VM_SHARED); +} + +static bool vma_fs_can_writeback(struct vm_area_struct *vma) +{ + /* No managed pages to writeback. */ + if (vma->vm_flags & VM_PFNMAP) + return false; + + return vma->vm_file && vma->vm_file->f_mapping && + mapping_can_writeback(vma->vm_file->f_mapping); +} + +/* + * Does this VMA require the underlying folios to have their dirty state + * tracked? + */ +bool vma_needs_dirty_tracking(struct vm_area_struct *vma) +{ + /* Only shared, writable VMAs require dirty tracking. */ + if (!vma_is_shared_writable(vma)) + return false; + + /* Does the filesystem need to be notified? */ + if (vm_ops_needs_writenotify(vma->vm_ops)) + return true; + + /* + * Even if the filesystem doesn't indicate a need for writenotify, if it + * can writeback, dirty tracking is still required. + */ + return vma_fs_can_writeback(vma); +} + +/* + * Some shared mappings will want the pages marked read-only + * to track write events. If so, we'll downgrade vm_page_prot + * to the private version (using protection_map[] without the + * VM_SHARED bit). + */ +bool vma_wants_writenotify(struct vm_area_struct *vma, pgprot_t vm_page_prot) +{ + /* If it was private or non-writable, the write bit is already clear */ + if (!vma_is_shared_writable(vma)) + return false; + + /* The backer wishes to know when pages are first written to? */ + if (vm_ops_needs_writenotify(vma->vm_ops)) + return true; + + /* The open routine did something to the protections that pgprot_modify + * won't preserve? */ + if (pgprot_val(vm_page_prot) != + pgprot_val(vm_pgprot_modify(vm_page_prot, vma->vm_flags))) + return false; + + /* + * Do we need to track softdirty? hugetlb does not support softdirty + * tracking yet. + */ + if (vma_soft_dirty_enabled(vma) && !is_vm_hugetlb_page(vma)) + return true; + + /* Do we need write faults for uffd-wp tracking? */ + if (userfaultfd_wp(vma)) + return true; + + /* Can the mapping track the dirty pages? */ + return vma_fs_can_writeback(vma); +} + +static DEFINE_MUTEX(mm_all_locks_mutex); + +static void vm_lock_anon_vma(struct mm_struct *mm, struct anon_vma *anon_vma) +{ + if (!test_bit(0, (unsigned long *) &anon_vma->root->rb_root.rb_root.rb_node)) { + /* + * The LSB of head.next can't change from under us + * because we hold the mm_all_locks_mutex. + */ + down_write_nest_lock(&anon_vma->root->rwsem, &mm->mmap_lock); + /* + * We can safely modify head.next after taking the + * anon_vma->root->rwsem. If some other vma in this mm shares + * the same anon_vma we won't take it again. + * + * No need of atomic instructions here, head.next + * can't change from under us thanks to the + * anon_vma->root->rwsem. + */ + if (__test_and_set_bit(0, (unsigned long *) + &anon_vma->root->rb_root.rb_root.rb_node)) + BUG(); + } +} + +static void vm_lock_mapping(struct mm_struct *mm, struct address_space *mapping) +{ + if (!test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) { + /* + * AS_MM_ALL_LOCKS can't change from under us because + * we hold the mm_all_locks_mutex. + * + * Operations on ->flags have to be atomic because + * even if AS_MM_ALL_LOCKS is stable thanks to the + * mm_all_locks_mutex, there may be other cpus + * changing other bitflags in parallel to us. + */ + if (test_and_set_bit(AS_MM_ALL_LOCKS, &mapping->flags)) + BUG(); + down_write_nest_lock(&mapping->i_mmap_rwsem, &mm->mmap_lock); + } +} + +/* + * This operation locks against the VM for all pte/vma/mm related + * operations that could ever happen on a certain mm. This includes + * vmtruncate, try_to_unmap, and all page faults. + * + * The caller must take the mmap_lock in write mode before calling + * mm_take_all_locks(). The caller isn't allowed to release the + * mmap_lock until mm_drop_all_locks() returns. + * + * mmap_lock in write mode is required in order to block all operations + * that could modify pagetables and free pages without need of + * altering the vma layout. It's also needed in write mode to avoid new + * anon_vmas to be associated with existing vmas. + * + * A single task can't take more than one mm_take_all_locks() in a row + * or it would deadlock. + * + * The LSB in anon_vma->rb_root.rb_node and the AS_MM_ALL_LOCKS bitflag in + * mapping->flags avoid to take the same lock twice, if more than one + * vma in this mm is backed by the same anon_vma or address_space. + * + * We take locks in following order, accordingly to comment at beginning + * of mm/rmap.c: + * - all hugetlbfs_i_mmap_rwsem_key locks (aka mapping->i_mmap_rwsem for + * hugetlb mapping); + * - all vmas marked locked + * - all i_mmap_rwsem locks; + * - all anon_vma->rwseml + * + * We can take all locks within these types randomly because the VM code + * doesn't nest them and we protected from parallel mm_take_all_locks() by + * mm_all_locks_mutex. + * + * mm_take_all_locks() and mm_drop_all_locks are expensive operations + * that may have to take thousand of locks. + * + * mm_take_all_locks() can fail if it's interrupted by signals. + */ +int mm_take_all_locks(struct mm_struct *mm) +{ + struct vm_area_struct *vma; + struct anon_vma_chain *avc; + VMA_ITERATOR(vmi, mm, 0); + + mmap_assert_write_locked(mm); + + mutex_lock(&mm_all_locks_mutex); + + /* + * vma_start_write() does not have a complement in mm_drop_all_locks() + * because vma_start_write() is always asymmetrical; it marks a VMA as + * being written to until mmap_write_unlock() or mmap_write_downgrade() + * is reached. + */ + for_each_vma(vmi, vma) { + if (signal_pending(current)) + goto out_unlock; + vma_start_write(vma); + } + + vma_iter_init(&vmi, mm, 0); + for_each_vma(vmi, vma) { + if (signal_pending(current)) + goto out_unlock; + if (vma->vm_file && vma->vm_file->f_mapping && + is_vm_hugetlb_page(vma)) + vm_lock_mapping(mm, vma->vm_file->f_mapping); + } + + vma_iter_init(&vmi, mm, 0); + for_each_vma(vmi, vma) { + if (signal_pending(current)) + goto out_unlock; + if (vma->vm_file && vma->vm_file->f_mapping && + !is_vm_hugetlb_page(vma)) + vm_lock_mapping(mm, vma->vm_file->f_mapping); + } + + vma_iter_init(&vmi, mm, 0); + for_each_vma(vmi, vma) { + if (signal_pending(current)) + goto out_unlock; + if (vma->anon_vma) + list_for_each_entry(avc, &vma->anon_vma_chain, same_vma) + vm_lock_anon_vma(mm, avc->anon_vma); + } + + return 0; + +out_unlock: + mm_drop_all_locks(mm); + return -EINTR; +} + +static void vm_unlock_anon_vma(struct anon_vma *anon_vma) +{ + if (test_bit(0, (unsigned long *) &anon_vma->root->rb_root.rb_root.rb_node)) { + /* + * The LSB of head.next can't change to 0 from under + * us because we hold the mm_all_locks_mutex. + * + * We must however clear the bitflag before unlocking + * the vma so the users using the anon_vma->rb_root will + * never see our bitflag. + * + * No need of atomic instructions here, head.next + * can't change from under us until we release the + * anon_vma->root->rwsem. + */ + if (!__test_and_clear_bit(0, (unsigned long *) + &anon_vma->root->rb_root.rb_root.rb_node)) + BUG(); + anon_vma_unlock_write(anon_vma); + } +} + +static void vm_unlock_mapping(struct address_space *mapping) +{ + if (test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) { + /* + * AS_MM_ALL_LOCKS can't change to 0 from under us + * because we hold the mm_all_locks_mutex. + */ + i_mmap_unlock_write(mapping); + if (!test_and_clear_bit(AS_MM_ALL_LOCKS, + &mapping->flags)) + BUG(); + } +} + +/* + * The mmap_lock cannot be released by the caller until + * mm_drop_all_locks() returns. + */ +void mm_drop_all_locks(struct mm_struct *mm) +{ + struct vm_area_struct *vma; + struct anon_vma_chain *avc; + VMA_ITERATOR(vmi, mm, 0); + + mmap_assert_write_locked(mm); + BUG_ON(!mutex_is_locked(&mm_all_locks_mutex)); + + for_each_vma(vmi, vma) { + if (vma->anon_vma) + list_for_each_entry(avc, &vma->anon_vma_chain, same_vma) + vm_unlock_anon_vma(avc->anon_vma); + if (vma->vm_file && vma->vm_file->f_mapping) + vm_unlock_mapping(vma->vm_file->f_mapping); + } + + mutex_unlock(&mm_all_locks_mutex); +} + +/* + * We account for memory if it's a private writeable mapping, + * not hugepages and VM_NORESERVE wasn't set. + */ +static bool accountable_mapping(struct file *file, vm_flags_t vm_flags) +{ + /* + * hugetlb has its own accounting separate from the core VM + * VM_HUGETLB may not be set yet so we cannot check for that flag. + */ + if (file && is_file_hugepages(file)) + return false; + + return (vm_flags & (VM_NORESERVE | VM_SHARED | VM_WRITE)) == VM_WRITE; +} + +/* + * vms_abort_munmap_vmas() - Undo as much as possible from an aborted munmap() + * operation. + * @vms: The vma unmap structure + * @mas_detach: The maple state with the detached maple tree + * + * Reattach any detached vmas, free up the maple tree used to track the vmas. + * If that's not possible because the ptes are cleared (and vm_ops->closed() may + * have been called), then a NULL is written over the vmas and the vmas are + * removed (munmap() completed). + */ +static void vms_abort_munmap_vmas(struct vma_munmap_struct *vms, + struct ma_state *mas_detach) +{ + struct ma_state *mas = &vms->vmi->mas; + + if (!vms->nr_pages) + return; + + if (vms->clear_ptes) + return reattach_vmas(mas_detach); + + /* + * Aborting cannot just call the vm_ops open() because they are often + * not symmetrical and state data has been lost. Resort to the old + * failure method of leaving a gap where the MAP_FIXED mapping failed. + */ + mas_set_range(mas, vms->start, vms->end - 1); + mas_store_gfp(mas, NULL, GFP_KERNEL|__GFP_NOFAIL); + /* Clean up the insertion of the unfortunate gap */ + vms_complete_munmap_vmas(vms, mas_detach); +} + +/* + * __mmap_prepare() - Prepare to gather any overlapping VMAs that need to be + * unmapped once the map operation is completed, check limits, account mapping + * and clean up any pre-existing VMAs. + * + * @map: Mapping state. + * @uf: Userfaultfd context list. + * + * Returns: 0 on success, error code otherwise. + */ +static int __mmap_prepare(struct mmap_state *map, struct list_head *uf) +{ + int error; + struct vma_iterator *vmi = map->vmi; + struct vma_munmap_struct *vms = &map->vms; + + /* Find the first overlapping VMA and initialise unmap state. */ + vms->vma = vma_find(vmi, map->end); + init_vma_munmap(vms, vmi, vms->vma, map->addr, map->end, uf, + /* unlock = */ false); + + /* OK, we have overlapping VMAs - prepare to unmap them. */ + if (vms->vma) { + mt_init_flags(&map->mt_detach, + vmi->mas.tree->ma_flags & MT_FLAGS_LOCK_MASK); + mt_on_stack(map->mt_detach); + mas_init(&map->mas_detach, &map->mt_detach, /* addr = */ 0); + /* Prepare to unmap any existing mapping in the area */ + error = vms_gather_munmap_vmas(vms, &map->mas_detach); + if (error) { + /* On error VMAs will already have been reattached. */ + vms->nr_pages = 0; + return error; + } + + map->next = vms->next; + map->prev = vms->prev; + } else { + map->next = vma_iter_next_rewind(vmi, &map->prev); + } + + /* Check against address space limit. */ + if (!may_expand_vm(map->mm, map->flags, map->pglen - vms->nr_pages)) + return -ENOMEM; + + /* Private writable mapping: check memory availability. */ + if (accountable_mapping(map->file, map->flags)) { + map->charged = map->pglen; + map->charged -= vms->nr_accounted; + if (map->charged) { + error = security_vm_enough_memory_mm(map->mm, map->charged); + if (error) + return error; + } + + vms->nr_accounted = 0; + map->flags |= VM_ACCOUNT; + } + + /* + * Clear PTEs while the vma is still in the tree so that rmap + * cannot race with the freeing later in the truncate scenario. + * This is also needed for mmap_file(), which is why vm_ops + * close function is called. + */ + vms_clean_up_area(vms, &map->mas_detach); + + return 0; +} + + +static int __mmap_new_file_vma(struct mmap_state *map, + struct vm_area_struct *vma) +{ + struct vma_iterator *vmi = map->vmi; + int error; + + vma->vm_file = get_file(map->file); + + if (!map->file->f_op->mmap) + return 0; + + error = mmap_file(vma->vm_file, vma); + if (error) { + fput(vma->vm_file); + vma->vm_file = NULL; + + vma_iter_set(vmi, vma->vm_end); + /* Undo any partial mapping done by a device driver. */ + unmap_region(&vmi->mas, vma, map->prev, map->next); + + return error; + } + + /* Drivers cannot alter the address of the VMA. */ + WARN_ON_ONCE(map->addr != vma->vm_start); + /* + * Drivers should not permit writability when previously it was + * disallowed. + */ + VM_WARN_ON_ONCE(map->flags != vma->vm_flags && + !(map->flags & VM_MAYWRITE) && + (vma->vm_flags & VM_MAYWRITE)); + + map->flags = vma->vm_flags; + + return 0; +} + +/* + * __mmap_new_vma() - Allocate a new VMA for the region, as merging was not + * possible. + * + * @map: Mapping state. + * @vmap: Output pointer for the new VMA. + * + * Returns: Zero on success, or an error. + */ +static int __mmap_new_vma(struct mmap_state *map, struct vm_area_struct **vmap) +{ + struct vma_iterator *vmi = map->vmi; + int error = 0; + struct vm_area_struct *vma; + + /* + * Determine the object being mapped and call the appropriate + * specific mapper. the address has already been validated, but + * not unmapped, but the maps are removed from the list. + */ + vma = vm_area_alloc(map->mm); + if (!vma) + return -ENOMEM; + + vma_iter_config(vmi, map->addr, map->end); + vma_set_range(vma, map->addr, map->end, map->pgoff); + vm_flags_init(vma, map->flags); + vma->vm_page_prot = map->page_prot; + + if (vma_iter_prealloc(vmi, vma)) { + error = -ENOMEM; + goto free_vma; + } + + if (map->file) + error = __mmap_new_file_vma(map, vma); + else if (map->flags & VM_SHARED) + error = shmem_zero_setup(vma); + else + vma_set_anonymous(vma); + + if (error) + goto free_iter_vma; + +#ifdef CONFIG_SPARC64 + /* TODO: Fix SPARC ADI! */ + WARN_ON_ONCE(!arch_validate_flags(map->flags)); +#endif + + /* Lock the VMA since it is modified after insertion into VMA tree */ + vma_start_write(vma); + vma_iter_store_new(vmi, vma); + map->mm->map_count++; + vma_link_file(vma); + + /* + * vma_merge_new_range() calls khugepaged_enter_vma() too, the below + * call covers the non-merge case. + */ + if (!vma_is_anonymous(vma)) + khugepaged_enter_vma(vma, map->flags); + ksm_add_vma(vma); + *vmap = vma; + return 0; + +free_iter_vma: + vma_iter_free(vmi); +free_vma: + vm_area_free(vma); + return error; +} + +/* + * __mmap_complete() - Unmap any VMAs we overlap, account memory mapping + * statistics, handle locking and finalise the VMA. + * + * @map: Mapping state. + * @vma: Merged or newly allocated VMA for the mmap()'d region. + */ +static void __mmap_complete(struct mmap_state *map, struct vm_area_struct *vma) +{ + struct mm_struct *mm = map->mm; + unsigned long vm_flags = vma->vm_flags; + + perf_event_mmap(vma); + + /* Unmap any existing mapping in the area. */ + vms_complete_munmap_vmas(&map->vms, &map->mas_detach); + + vm_stat_account(mm, vma->vm_flags, map->pglen); + if (vm_flags & VM_LOCKED) { + if ((vm_flags & VM_SPECIAL) || vma_is_dax(vma) || + is_vm_hugetlb_page(vma) || + vma == get_gate_vma(mm)) + vm_flags_clear(vma, VM_LOCKED_MASK); + else + mm->locked_vm += map->pglen; + } + + if (vma->vm_file) + uprobe_mmap(vma); + + /* + * New (or expanded) vma always get soft dirty status. + * Otherwise user-space soft-dirty page tracker won't + * be able to distinguish situation when vma area unmapped, + * then new mapped in-place (which must be aimed as + * a completely new data area). + */ + vm_flags_set(vma, VM_SOFTDIRTY); + + vma_set_page_prot(vma); +} + +/* + * Invoke the f_op->mmap_prepare() callback for a file-backed mapping that + * specifies it. + * + * This is called prior to any merge attempt, and updates whitelisted fields + * that are permitted to be updated by the caller. + * + * All but user-defined fields will be pre-populated with original values. + * + * Returns 0 on success, or an error code otherwise. + */ +static int call_mmap_prepare(struct mmap_state *map) +{ + int err; + struct vm_area_desc desc = { + .mm = map->mm, + .start = map->addr, + .end = map->end, + + .pgoff = map->pgoff, + .file = map->file, + .vm_flags = map->flags, + .page_prot = map->page_prot, + }; + + /* Invoke the hook. */ + err = __call_mmap_prepare(map->file, &desc); + if (err) + return err; + + /* Update fields permitted to be changed. */ + map->pgoff = desc.pgoff; + map->file = desc.file; + map->flags = desc.vm_flags; + map->page_prot = desc.page_prot; + /* User-defined fields. */ + map->vm_ops = desc.vm_ops; + map->vm_private_data = desc.private_data; + + return 0; +} + +static void set_vma_user_defined_fields(struct vm_area_struct *vma, + struct mmap_state *map) +{ + if (map->vm_ops) + vma->vm_ops = map->vm_ops; + vma->vm_private_data = map->vm_private_data; +} + +static unsigned long __mmap_region(struct file *file, unsigned long addr, + unsigned long len, vm_flags_t vm_flags, unsigned long pgoff, + struct list_head *uf) +{ + struct mm_struct *mm = current->mm; + struct vm_area_struct *vma = NULL; + int error; + bool have_mmap_prepare = file && file->f_op->mmap_prepare; + VMA_ITERATOR(vmi, mm, addr); + MMAP_STATE(map, mm, &vmi, addr, len, pgoff, vm_flags, file); + + error = __mmap_prepare(&map, uf); + if (!error && have_mmap_prepare) + error = call_mmap_prepare(&map); + if (error) + goto abort_munmap; + + /* Attempt to merge with adjacent VMAs... */ + if (map.prev || map.next) { + VMG_MMAP_STATE(vmg, &map, /* vma = */ NULL); + + vma = vma_merge_new_range(&vmg); + } + + /* ...but if we can't, allocate a new VMA. */ + if (!vma) { + error = __mmap_new_vma(&map, &vma); + if (error) + goto unacct_error; + } + + if (have_mmap_prepare) + set_vma_user_defined_fields(vma, &map); + + __mmap_complete(&map, vma); + + return addr; + + /* Accounting was done by __mmap_prepare(). */ +unacct_error: + if (map.charged) + vm_unacct_memory(map.charged); +abort_munmap: + vms_abort_munmap_vmas(&map.vms, &map.mas_detach); + return error; +} + +/** + * mmap_region() - Actually perform the userland mapping of a VMA into + * current->mm with known, aligned and overflow-checked @addr and @len, and + * correctly determined VMA flags @vm_flags and page offset @pgoff. + * + * This is an internal memory management function, and should not be used + * directly. + * + * The caller must write-lock current->mm->mmap_lock. + * + * @file: If a file-backed mapping, a pointer to the struct file describing the + * file to be mapped, otherwise NULL. + * @addr: The page-aligned address at which to perform the mapping. + * @len: The page-aligned, non-zero, length of the mapping. + * @vm_flags: The VMA flags which should be applied to the mapping. + * @pgoff: If @file is specified, the page offset into the file, if not then + * the virtual page offset in memory of the anonymous mapping. + * @uf: Optionally, a pointer to a list head used for tracking userfaultfd unmap + * events. + * + * Returns: Either an error, or the address at which the requested mapping has + * been performed. + */ +unsigned long mmap_region(struct file *file, unsigned long addr, + unsigned long len, vm_flags_t vm_flags, unsigned long pgoff, + struct list_head *uf) +{ + unsigned long ret; + bool writable_file_mapping = false; + + mmap_assert_write_locked(current->mm); + + /* Check to see if MDWE is applicable. */ + if (map_deny_write_exec(vm_flags, vm_flags)) + return -EACCES; + + /* Allow architectures to sanity-check the vm_flags. */ + if (!arch_validate_flags(vm_flags)) + return -EINVAL; + + /* Map writable and ensure this isn't a sealed memfd. */ + if (file && is_shared_maywrite(vm_flags)) { + int error = mapping_map_writable(file->f_mapping); + + if (error) + return error; + writable_file_mapping = true; + } + + ret = __mmap_region(file, addr, len, vm_flags, pgoff, uf); + + /* Clear our write mapping regardless of error. */ + if (writable_file_mapping) + mapping_unmap_writable(file->f_mapping); + + validate_mm(current->mm); + return ret; +} + +/* + * do_brk_flags() - Increase the brk vma if the flags match. + * @vmi: The vma iterator + * @addr: The start address + * @len: The length of the increase + * @vma: The vma, + * @flags: The VMA Flags + * + * Extend the brk VMA from addr to addr + len. If the VMA is NULL or the flags + * do not match then create a new anonymous VMA. Eventually we may be able to + * do some brk-specific accounting here. + */ +int do_brk_flags(struct vma_iterator *vmi, struct vm_area_struct *vma, + unsigned long addr, unsigned long len, unsigned long flags) +{ + struct mm_struct *mm = current->mm; + + /* + * Check against address space limits by the changed size + * Note: This happens *after* clearing old mappings in some code paths. + */ + flags |= VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags; + if (!may_expand_vm(mm, flags, len >> PAGE_SHIFT)) + return -ENOMEM; + + if (mm->map_count > sysctl_max_map_count) + return -ENOMEM; + + if (security_vm_enough_memory_mm(mm, len >> PAGE_SHIFT)) + return -ENOMEM; + + /* + * Expand the existing vma if possible; Note that singular lists do not + * occur after forking, so the expand will only happen on new VMAs. + */ + if (vma && vma->vm_end == addr) { + VMG_STATE(vmg, mm, vmi, addr, addr + len, flags, PHYS_PFN(addr)); + + vmg.prev = vma; + /* vmi is positioned at prev, which this mode expects. */ + vmg.just_expand = true; + + if (vma_merge_new_range(&vmg)) + goto out; + else if (vmg_nomem(&vmg)) + goto unacct_fail; + } + + if (vma) + vma_iter_next_range(vmi); + /* create a vma struct for an anonymous mapping */ + vma = vm_area_alloc(mm); + if (!vma) + goto unacct_fail; + + vma_set_anonymous(vma); + vma_set_range(vma, addr, addr + len, addr >> PAGE_SHIFT); + vm_flags_init(vma, flags); + vma->vm_page_prot = vm_get_page_prot(flags); + vma_start_write(vma); + if (vma_iter_store_gfp(vmi, vma, GFP_KERNEL)) + goto mas_store_fail; + + mm->map_count++; + validate_mm(mm); + ksm_add_vma(vma); +out: + perf_event_mmap(vma); + mm->total_vm += len >> PAGE_SHIFT; + mm->data_vm += len >> PAGE_SHIFT; + if (flags & VM_LOCKED) + mm->locked_vm += (len >> PAGE_SHIFT); + vm_flags_set(vma, VM_SOFTDIRTY); + return 0; + +mas_store_fail: + vm_area_free(vma); +unacct_fail: + vm_unacct_memory(len >> PAGE_SHIFT); + return -ENOMEM; +} + +/** + * unmapped_area() - Find an area between the low_limit and the high_limit with + * the correct alignment and offset, all from @info. Note: current->mm is used + * for the search. + * + * @info: The unmapped area information including the range [low_limit - + * high_limit), the alignment offset and mask. + * + * Return: A memory address or -ENOMEM. + */ +unsigned long unmapped_area(struct vm_unmapped_area_info *info) +{ + unsigned long length, gap; + unsigned long low_limit, high_limit; + struct vm_area_struct *tmp; + VMA_ITERATOR(vmi, current->mm, 0); + + /* Adjust search length to account for worst case alignment overhead */ + length = info->length + info->align_mask + info->start_gap; + if (length < info->length) + return -ENOMEM; + + low_limit = info->low_limit; + if (low_limit < mmap_min_addr) + low_limit = mmap_min_addr; + high_limit = info->high_limit; +retry: + if (vma_iter_area_lowest(&vmi, low_limit, high_limit, length)) + return -ENOMEM; + + /* + * Adjust for the gap first so it doesn't interfere with the + * later alignment. The first step is the minimum needed to + * fulill the start gap, the next steps is the minimum to align + * that. It is the minimum needed to fulill both. + */ + gap = vma_iter_addr(&vmi) + info->start_gap; + gap += (info->align_offset - gap) & info->align_mask; + tmp = vma_next(&vmi); + if (tmp && (tmp->vm_flags & VM_STARTGAP_FLAGS)) { /* Avoid prev check if possible */ + if (vm_start_gap(tmp) < gap + length - 1) { + low_limit = tmp->vm_end; + vma_iter_reset(&vmi); + goto retry; + } + } else { + tmp = vma_prev(&vmi); + if (tmp && vm_end_gap(tmp) > gap) { + low_limit = vm_end_gap(tmp); + vma_iter_reset(&vmi); + goto retry; + } + } + + return gap; +} + +/** + * unmapped_area_topdown() - Find an area between the low_limit and the + * high_limit with the correct alignment and offset at the highest available + * address, all from @info. Note: current->mm is used for the search. + * + * @info: The unmapped area information including the range [low_limit - + * high_limit), the alignment offset and mask. + * + * Return: A memory address or -ENOMEM. + */ +unsigned long unmapped_area_topdown(struct vm_unmapped_area_info *info) +{ + unsigned long length, gap, gap_end; + unsigned long low_limit, high_limit; + struct vm_area_struct *tmp; + VMA_ITERATOR(vmi, current->mm, 0); + + /* Adjust search length to account for worst case alignment overhead */ + length = info->length + info->align_mask + info->start_gap; + if (length < info->length) + return -ENOMEM; + + low_limit = info->low_limit; + if (low_limit < mmap_min_addr) + low_limit = mmap_min_addr; + high_limit = info->high_limit; +retry: + if (vma_iter_area_highest(&vmi, low_limit, high_limit, length)) + return -ENOMEM; + + gap = vma_iter_end(&vmi) - info->length; + gap -= (gap - info->align_offset) & info->align_mask; + gap_end = vma_iter_end(&vmi); + tmp = vma_next(&vmi); + if (tmp && (tmp->vm_flags & VM_STARTGAP_FLAGS)) { /* Avoid prev check if possible */ + if (vm_start_gap(tmp) < gap_end) { + high_limit = vm_start_gap(tmp); + vma_iter_reset(&vmi); + goto retry; + } + } else { + tmp = vma_prev(&vmi); + if (tmp && vm_end_gap(tmp) > gap) { + high_limit = tmp->vm_start; + vma_iter_reset(&vmi); + goto retry; + } + } + + return gap; +} + +/* + * Verify that the stack growth is acceptable and + * update accounting. This is shared with both the + * grow-up and grow-down cases. + */ +static int acct_stack_growth(struct vm_area_struct *vma, + unsigned long size, unsigned long grow) +{ + struct mm_struct *mm = vma->vm_mm; + unsigned long new_start; + + /* address space limit tests */ + if (!may_expand_vm(mm, vma->vm_flags, grow)) + return -ENOMEM; + + /* Stack limit test */ + if (size > rlimit(RLIMIT_STACK)) + return -ENOMEM; + + /* mlock limit tests */ + if (!mlock_future_ok(mm, vma->vm_flags, grow << PAGE_SHIFT)) + return -ENOMEM; + + /* Check to ensure the stack will not grow into a hugetlb-only region */ + new_start = (vma->vm_flags & VM_GROWSUP) ? vma->vm_start : + vma->vm_end - size; + if (is_hugepage_only_range(vma->vm_mm, new_start, size)) + return -EFAULT; + + /* + * Overcommit.. This must be the final test, as it will + * update security statistics. + */ + if (security_vm_enough_memory_mm(mm, grow)) + return -ENOMEM; + + return 0; +} + +#if defined(CONFIG_STACK_GROWSUP) +/* + * PA-RISC uses this for its stack. + * vma is the last one with address > vma->vm_end. Have to extend vma. + */ +int expand_upwards(struct vm_area_struct *vma, unsigned long address) +{ + struct mm_struct *mm = vma->vm_mm; + struct vm_area_struct *next; + unsigned long gap_addr; + int error = 0; + VMA_ITERATOR(vmi, mm, vma->vm_start); + + if (!(vma->vm_flags & VM_GROWSUP)) + return -EFAULT; + + mmap_assert_write_locked(mm); + + /* Guard against exceeding limits of the address space. */ + address &= PAGE_MASK; + if (address >= (TASK_SIZE & PAGE_MASK)) + return -ENOMEM; + address += PAGE_SIZE; + + /* Enforce stack_guard_gap */ + gap_addr = address + stack_guard_gap; + + /* Guard against overflow */ + if (gap_addr < address || gap_addr > TASK_SIZE) + gap_addr = TASK_SIZE; + + next = find_vma_intersection(mm, vma->vm_end, gap_addr); + if (next && vma_is_accessible(next)) { + if (!(next->vm_flags & VM_GROWSUP)) + return -ENOMEM; + /* Check that both stack segments have the same anon_vma? */ + } + + if (next) + vma_iter_prev_range_limit(&vmi, address); + + vma_iter_config(&vmi, vma->vm_start, address); + if (vma_iter_prealloc(&vmi, vma)) + return -ENOMEM; + + /* We must make sure the anon_vma is allocated. */ + if (unlikely(anon_vma_prepare(vma))) { + vma_iter_free(&vmi); + return -ENOMEM; + } + + /* Lock the VMA before expanding to prevent concurrent page faults */ + vma_start_write(vma); + /* We update the anon VMA tree. */ + anon_vma_lock_write(vma->anon_vma); + + /* Somebody else might have raced and expanded it already */ + if (address > vma->vm_end) { + unsigned long size, grow; + + size = address - vma->vm_start; + grow = (address - vma->vm_end) >> PAGE_SHIFT; + + error = -ENOMEM; + if (vma->vm_pgoff + (size >> PAGE_SHIFT) >= vma->vm_pgoff) { + error = acct_stack_growth(vma, size, grow); + if (!error) { + if (vma->vm_flags & VM_LOCKED) + mm->locked_vm += grow; + vm_stat_account(mm, vma->vm_flags, grow); + anon_vma_interval_tree_pre_update_vma(vma); + vma->vm_end = address; + /* Overwrite old entry in mtree. */ + vma_iter_store_overwrite(&vmi, vma); + anon_vma_interval_tree_post_update_vma(vma); + + perf_event_mmap(vma); + } + } + } + anon_vma_unlock_write(vma->anon_vma); + vma_iter_free(&vmi); + validate_mm(mm); + return error; +} +#endif /* CONFIG_STACK_GROWSUP */ + +/* + * vma is the first one with address < vma->vm_start. Have to extend vma. + * mmap_lock held for writing. + */ +int expand_downwards(struct vm_area_struct *vma, unsigned long address) +{ + struct mm_struct *mm = vma->vm_mm; + struct vm_area_struct *prev; + int error = 0; + VMA_ITERATOR(vmi, mm, vma->vm_start); + + if (!(vma->vm_flags & VM_GROWSDOWN)) + return -EFAULT; + + mmap_assert_write_locked(mm); + + address &= PAGE_MASK; + if (address < mmap_min_addr || address < FIRST_USER_ADDRESS) + return -EPERM; + + /* Enforce stack_guard_gap */ + prev = vma_prev(&vmi); + /* Check that both stack segments have the same anon_vma? */ + if (prev) { + if (!(prev->vm_flags & VM_GROWSDOWN) && + vma_is_accessible(prev) && + (address - prev->vm_end < stack_guard_gap)) + return -ENOMEM; + } + + if (prev) + vma_iter_next_range_limit(&vmi, vma->vm_start); + + vma_iter_config(&vmi, address, vma->vm_end); + if (vma_iter_prealloc(&vmi, vma)) + return -ENOMEM; + + /* We must make sure the anon_vma is allocated. */ + if (unlikely(anon_vma_prepare(vma))) { + vma_iter_free(&vmi); + return -ENOMEM; + } + + /* Lock the VMA before expanding to prevent concurrent page faults */ + vma_start_write(vma); + /* We update the anon VMA tree. */ + anon_vma_lock_write(vma->anon_vma); + + /* Somebody else might have raced and expanded it already */ + if (address < vma->vm_start) { + unsigned long size, grow; + + size = vma->vm_end - address; + grow = (vma->vm_start - address) >> PAGE_SHIFT; + + error = -ENOMEM; + if (grow <= vma->vm_pgoff) { + error = acct_stack_growth(vma, size, grow); + if (!error) { + if (vma->vm_flags & VM_LOCKED) + mm->locked_vm += grow; + vm_stat_account(mm, vma->vm_flags, grow); + anon_vma_interval_tree_pre_update_vma(vma); + vma->vm_start = address; + vma->vm_pgoff -= grow; + /* Overwrite old entry in mtree. */ + vma_iter_store_overwrite(&vmi, vma); + anon_vma_interval_tree_post_update_vma(vma); + + perf_event_mmap(vma); + } + } + } + anon_vma_unlock_write(vma->anon_vma); + vma_iter_free(&vmi); + validate_mm(mm); + return error; +} + +int __vm_munmap(unsigned long start, size_t len, bool unlock) +{ + int ret; + struct mm_struct *mm = current->mm; + LIST_HEAD(uf); + VMA_ITERATOR(vmi, mm, start); + + if (mmap_write_lock_killable(mm)) + return -EINTR; + + ret = do_vmi_munmap(&vmi, mm, start, len, &uf, unlock); + if (ret || !unlock) + mmap_write_unlock(mm); + + userfaultfd_unmap_complete(mm, &uf); + return ret; +} + +/* Insert vm structure into process list sorted by address + * and into the inode's i_mmap tree. If vm_file is non-NULL + * then i_mmap_rwsem is taken here. + */ +int insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma) +{ + unsigned long charged = vma_pages(vma); + + + if (find_vma_intersection(mm, vma->vm_start, vma->vm_end)) + return -ENOMEM; + + if ((vma->vm_flags & VM_ACCOUNT) && + security_vm_enough_memory_mm(mm, charged)) + return -ENOMEM; + + /* + * The vm_pgoff of a purely anonymous vma should be irrelevant + * until its first write fault, when page's anon_vma and index + * are set. But now set the vm_pgoff it will almost certainly + * end up with (unless mremap moves it elsewhere before that + * first wfault), so /proc/pid/maps tells a consistent story. + * + * By setting it to reflect the virtual start address of the + * vma, merges and splits can happen in a seamless way, just + * using the existing file pgoff checks and manipulations. + * Similarly in do_mmap and in do_brk_flags. + */ + if (vma_is_anonymous(vma)) { + BUG_ON(vma->anon_vma); + vma->vm_pgoff = vma->vm_start >> PAGE_SHIFT; + } + + if (vma_link(mm, vma)) { + if (vma->vm_flags & VM_ACCOUNT) + vm_unacct_memory(charged); + return -ENOMEM; + } + + return 0; +} |