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authorBibo Mao <maobibo@loongson.cn>2020-05-27 10:25:18 +0800
committerThomas Bogendoerfer <tsbogend@alpha.franken.de>2020-05-27 13:06:09 +0200
commit7df676974359f927056b882e10a5b24d2033169b (patch)
treed8f0fc569f5d1f3003d35dd9788ab58bb8380553 /mm/memory.c
parent4dd7683ea1d66975fb258d02f2b74a7e9a32b131 (diff)
mm/memory.c: Update local TLB if PTE entry exists
If two threads concurrently fault at the same page, the thread that won the race updates the PTE and its local TLB. For now, the other thread gives up, simply does nothing, and continues. It could happen that this second thread triggers another fault, whereby it only updates its local TLB while handling the fault. Instead of triggering another fault, let's directly update the local TLB of the second thread. Function update_mmu_tlb is used here to update local TLB on the second thread, and it is defined as empty on other arches. Signed-off-by: Bibo Mao <maobibo@loongson.cn> Acked-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Diffstat (limited to 'mm/memory.c')
-rw-r--r--mm/memory.c27
1 files changed, 19 insertions, 8 deletions
diff --git a/mm/memory.c b/mm/memory.c
index f703fe8c8346..8bb31c4d94d0 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2436,10 +2436,9 @@ static inline bool cow_user_page(struct page *dst, struct page *src,
if (!likely(pte_same(*vmf->pte, vmf->orig_pte))) {
/*
* Other thread has already handled the fault
- * and we don't need to do anything. If it's
- * not the case, the fault will be triggered
- * again on the same address.
+ * and update local tlb only
*/
+ update_mmu_tlb(vma, addr, vmf->pte);
ret = false;
goto pte_unlock;
}
@@ -2463,7 +2462,8 @@ static inline bool cow_user_page(struct page *dst, struct page *src,
vmf->pte = pte_offset_map_lock(mm, vmf->pmd, addr, &vmf->ptl);
locked = true;
if (!likely(pte_same(*vmf->pte, vmf->orig_pte))) {
- /* The PTE changed under us. Retry page fault. */
+ /* The PTE changed under us, update local tlb */
+ update_mmu_tlb(vma, addr, vmf->pte);
ret = false;
goto pte_unlock;
}
@@ -2752,6 +2752,7 @@ static vm_fault_t wp_page_copy(struct vm_fault *vmf)
new_page = old_page;
page_copied = 1;
} else {
+ update_mmu_tlb(vma, vmf->address, vmf->pte);
mem_cgroup_cancel_charge(new_page, memcg, false);
}
@@ -2812,6 +2813,7 @@ vm_fault_t finish_mkwrite_fault(struct vm_fault *vmf)
* pte_offset_map_lock.
*/
if (!pte_same(*vmf->pte, vmf->orig_pte)) {
+ update_mmu_tlb(vmf->vma, vmf->address, vmf->pte);
pte_unmap_unlock(vmf->pte, vmf->ptl);
return VM_FAULT_NOPAGE;
}
@@ -2936,6 +2938,7 @@ static vm_fault_t do_wp_page(struct vm_fault *vmf)
vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd,
vmf->address, &vmf->ptl);
if (!pte_same(*vmf->pte, vmf->orig_pte)) {
+ update_mmu_tlb(vma, vmf->address, vmf->pte);
unlock_page(vmf->page);
pte_unmap_unlock(vmf->pte, vmf->ptl);
put_page(vmf->page);
@@ -3341,8 +3344,10 @@ static vm_fault_t do_anonymous_page(struct vm_fault *vmf)
vma->vm_page_prot));
vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd,
vmf->address, &vmf->ptl);
- if (!pte_none(*vmf->pte))
+ if (!pte_none(*vmf->pte)) {
+ update_mmu_tlb(vma, vmf->address, vmf->pte);
goto unlock;
+ }
ret = check_stable_address_space(vma->vm_mm);
if (ret)
goto unlock;
@@ -3378,8 +3383,10 @@ static vm_fault_t do_anonymous_page(struct vm_fault *vmf)
vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address,
&vmf->ptl);
- if (!pte_none(*vmf->pte))
+ if (!pte_none(*vmf->pte)) {
+ update_mmu_cache(vma, vmf->address, vmf->pte);
goto release;
+ }
ret = check_stable_address_space(vma->vm_mm);
if (ret)
@@ -3646,8 +3653,10 @@ vm_fault_t alloc_set_pte(struct vm_fault *vmf, struct mem_cgroup *memcg,
}
/* Re-check under ptl */
- if (unlikely(!pte_none(*vmf->pte)))
+ if (unlikely(!pte_none(*vmf->pte))) {
+ update_mmu_tlb(vma, vmf->address, vmf->pte);
return VM_FAULT_NOPAGE;
+ }
flush_icache_page(vma, page);
entry = mk_pte(page, vma->vm_page_prot);
@@ -4224,8 +4233,10 @@ static vm_fault_t handle_pte_fault(struct vm_fault *vmf)
vmf->ptl = pte_lockptr(vmf->vma->vm_mm, vmf->pmd);
spin_lock(vmf->ptl);
entry = vmf->orig_pte;
- if (unlikely(!pte_same(*vmf->pte, entry)))
+ if (unlikely(!pte_same(*vmf->pte, entry))) {
+ update_mmu_tlb(vmf->vma, vmf->address, vmf->pte);
goto unlock;
+ }
if (vmf->flags & FAULT_FLAG_WRITE) {
if (!pte_write(entry))
return do_wp_page(vmf);