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authorMatthew Wilcox (Oracle) <willy@infradead.org>2023-07-24 21:54:10 +0300
committerAndrew Morton <akpm@linux-foundation.org>2023-08-18 20:12:53 +0300
commit063e60d806151f3733acabccb62a463d55fac469 (patch)
tree67db5dafc4d71cc8e29641f2091d15534f59f504 /mm/memory.c
parent4c2f803abb1797e571579adcaf134a727b3ffc48 (diff)
downloadlinux-063e60d806151f3733acabccb62a463d55fac469.tar.xz
mm: handle faults that merely update the accessed bit under the VMA lock
Move FAULT_FLAG_VMA_LOCK check out of handle_pte_fault(). This should have a significant performance improvement for mmaped files. Write faults (on read-only shared pages) still take the mmap lock as we do not want to audit all the implementations of ->pfn_mkwrite() and ->page_mkwrite(). However write-faults on private mappings are handled under the VMA lock. [willy@infradead.org: address "suspicious RCU usage" warning] Link: https://lkml.kernel.org/r/ZMK7jwpI4uD6tKrF@casper.infradead.org Link: https://lkml.kernel.org/r/20230724185410.1124082-11-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Arjun Roy <arjunroy@google.com> Cc: Eric Dumazet <edumazet@google.com> Cc: Punit Agrawal <punit.agrawal@bytedance.com> Cc: Suren Baghdasaryan <surenb@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm/memory.c')
-rw-r--r--mm/memory.c23
1 files changed, 17 insertions, 6 deletions
diff --git a/mm/memory.c b/mm/memory.c
index c122adce47b4..f06266464208 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -3268,6 +3268,11 @@ static vm_fault_t wp_pfn_shared(struct vm_fault *vmf)
vm_fault_t ret;
pte_unmap_unlock(vmf->pte, vmf->ptl);
+ if (vmf->flags & FAULT_FLAG_VMA_LOCK) {
+ vma_end_read(vmf->vma);
+ return VM_FAULT_RETRY;
+ }
+
vmf->flags |= FAULT_FLAG_MKWRITE;
ret = vma->vm_ops->pfn_mkwrite(vmf);
if (ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE))
@@ -3290,6 +3295,12 @@ static vm_fault_t wp_page_shared(struct vm_fault *vmf, struct folio *folio)
vm_fault_t tmp;
pte_unmap_unlock(vmf->pte, vmf->ptl);
+ if (vmf->flags & FAULT_FLAG_VMA_LOCK) {
+ folio_put(folio);
+ vma_end_read(vmf->vma);
+ return VM_FAULT_RETRY;
+ }
+
tmp = do_page_mkwrite(vmf, folio);
if (unlikely(!tmp || (tmp &
(VM_FAULT_ERROR | VM_FAULT_NOPAGE)))) {
@@ -3431,6 +3442,12 @@ reuse:
return 0;
}
copy:
+ if ((vmf->flags & FAULT_FLAG_VMA_LOCK) && !vma->anon_vma) {
+ pte_unmap_unlock(vmf->pte, vmf->ptl);
+ vma_end_read(vmf->vma);
+ return VM_FAULT_RETRY;
+ }
+
/*
* Ok, we need to copy. Oh, well..
*/
@@ -4985,12 +5002,6 @@ static vm_fault_t handle_pte_fault(struct vm_fault *vmf)
if (pte_protnone(vmf->orig_pte) && vma_is_accessible(vmf->vma))
return do_numa_page(vmf);
- if ((vmf->flags & FAULT_FLAG_VMA_LOCK) && !vma_is_anonymous(vmf->vma)) {
- pte_unmap(vmf->pte);
- vma_end_read(vmf->vma);
- return VM_FAULT_RETRY;
- }
-
spin_lock(vmf->ptl);
entry = vmf->orig_pte;
if (unlikely(!pte_same(ptep_get(vmf->pte), entry))) {