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authorDan Williams <dan.j.williams@intel.com>2017-11-29 16:10:28 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2017-11-29 18:40:42 -0800
commit31383c6865a578834dd953d9dbc88e6b19fe3997 (patch)
tree046db228487d9ffc716dcc8185957eb08a650f97
parent95a87982541932503d3f59aba4c30b0bde0a6294 (diff)
mm, hugetlbfs: introduce ->split() to vm_operations_struct
Patch series "device-dax: fix unaligned munmap handling" When device-dax is operating in huge-page mode we want it to behave like hugetlbfs and fail attempts to split vmas into unaligned ranges. It would be messy to teach the munmap path about device-dax alignment constraints in the same (hstate) way that hugetlbfs communicates this constraint. Instead, these patches introduce a new ->split() vm operation. This patch (of 2): The device-dax interface has similar constraints as hugetlbfs in that it requires the munmap path to unmap in huge page aligned units. Rather than add more custom vma handling code in __split_vma() introduce a new vm operation to perform this vma specific check. Link: http://lkml.kernel.org/r/151130418135.4029.6783191281930729710.stgit@dwillia2-desk3.amr.corp.intel.com Fixes: dee410792419 ("/dev/dax, core: file operations and dax-mmap") Signed-off-by: Dan Williams <dan.j.williams@intel.com> Cc: Jeff Moyer <jmoyer@redhat.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--include/linux/mm.h1
-rw-r--r--mm/hugetlb.c8
-rw-r--r--mm/mmap.c8
3 files changed, 14 insertions, 3 deletions
diff --git a/include/linux/mm.h b/include/linux/mm.h
index ee073146aaa7..b3b6a7e313e9 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -377,6 +377,7 @@ enum page_entry_size {
struct vm_operations_struct {
void (*open)(struct vm_area_struct * area);
void (*close)(struct vm_area_struct * area);
+ int (*split)(struct vm_area_struct * area, unsigned long addr);
int (*mremap)(struct vm_area_struct * area);
int (*fault)(struct vm_fault *vmf);
int (*huge_fault)(struct vm_fault *vmf, enum page_entry_size pe_size);
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 681b300185c0..698e8fb34031 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -3125,6 +3125,13 @@ static void hugetlb_vm_op_close(struct vm_area_struct *vma)
}
}
+static int hugetlb_vm_op_split(struct vm_area_struct *vma, unsigned long addr)
+{
+ if (addr & ~(huge_page_mask(hstate_vma(vma))))
+ return -EINVAL;
+ return 0;
+}
+
/*
* We cannot handle pagefaults against hugetlb pages at all. They cause
* handle_mm_fault() to try to instantiate regular-sized pages in the
@@ -3141,6 +3148,7 @@ const struct vm_operations_struct hugetlb_vm_ops = {
.fault = hugetlb_vm_op_fault,
.open = hugetlb_vm_op_open,
.close = hugetlb_vm_op_close,
+ .split = hugetlb_vm_op_split,
};
static pte_t make_huge_pte(struct vm_area_struct *vma, struct page *page,
diff --git a/mm/mmap.c b/mm/mmap.c
index 924839fac0e6..a4d546821214 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -2555,9 +2555,11 @@ int __split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
struct vm_area_struct *new;
int err;
- if (is_vm_hugetlb_page(vma) && (addr &
- ~(huge_page_mask(hstate_vma(vma)))))
- return -EINVAL;
+ if (vma->vm_ops && vma->vm_ops->split) {
+ err = vma->vm_ops->split(vma, addr);
+ if (err)
+ return err;
+ }
new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
if (!new)