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| author | Matthew Wilcox (Oracle) <willy@infradead.org> | 2023-07-24 19:54:10 +0100 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2023-08-18 10:12:53 -0700 |
| commit | 063e60d806151f3733acabccb62a463d55fac469 (patch) | |
| tree | 67db5dafc4d71cc8e29641f2091d15534f59f504 /mm/memory.c | |
| parent | 4c2f803abb1797e571579adcaf134a727b3ffc48 (diff) | |
| download | linux-063e60d806151f3733acabccb62a463d55fac469.tar.gz linux-063e60d806151f3733acabccb62a463d55fac469.tar.bz2 linux-063e60d806151f3733acabccb62a463d55fac469.zip | |
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.c | 23 |
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))) { |