The patch titled
Subject: mm: handle faults that merely update the accessed bit under the VMA lock
has been added to the -mm mm-unstable branch. Its filename is
mm-handle-faults-that-merely-update-the-accessed-bit-under-the-vma-lock.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-handle-faults-that-merely-update-the-accessed-bit-under-the-vma-lock.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: "Matthew Wilcox (Oracle)" <willy@xxxxxxxxxxxxx>
Subject: mm: handle faults that merely update the accessed bit under the VMA lock
Date: Mon, 24 Jul 2023 19:54:10 +0100
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.
Link: https://lkml.kernel.org/r/20230724185410.1124082-11-willy@xxxxxxxxxxxxx
Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Cc: Arjun Roy <arjunroy@xxxxxxxxxx>
Cc: Eric Dumazet <edumazet@xxxxxxxxxx>
Cc: Punit Agrawal <punit.agrawal@xxxxxxxxxxxxx>
Cc: Suren Baghdasaryan <surenb@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/memory.c | 17 +++++++++++------
1 file changed, 11 insertions(+), 6 deletions(-)
--- a/mm/memory.c~mm-handle-faults-that-merely-update-the-accessed-bit-under-the-vma-lock
+++ a/mm/memory.c
@@ -3391,6 +3391,11 @@ static vm_fault_t wp_pfn_shared(struct v
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))
@@ -3413,6 +3418,12 @@ static vm_fault_t wp_page_shared(struct
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)))) {
@@ -5111,12 +5122,6 @@ static vm_fault_t handle_pte_fault(struc
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))) {
_
Patches currently in -mm which might be from willy@xxxxxxxxxxxxx are
rmap-pass-the-folio-to-__page_check_anon_rmap.patch
highmem-add-memcpy_to_folio-and-memcpy_from_folio.patch
affs-convert-affs_symlink_read_folio-to-use-the-folio.patch
affs-convert-data-read-and-write-to-use-folios.patch
migrate-use-folio_set_bh-instead-of-set_bh_page.patch
ntfs3-convert-ntfs_get_block_vbo-to-use-a-folio.patch
jbd2-use-a-folio-in-jbd2_journal_write_metadata_buffer.patch
buffer-remove-set_bh_page.patch
zswap-make-zswap_store-take-a-folio.patch
memcg-convert-get_obj_cgroup_from_page-to-get_obj_cgroup_from_folio.patch
swap-remove-some-calls-to-compound_head-in-swap_readpage.patch
zswap-make-zswap_load-take-a-folio.patch
mm-remove-config_per_vma_lock-ifdefs.patch
mm-allow-per-vma-locks-on-file-backed-vmas.patch
mm-move-fault_flag_vma_lock-check-from-handle_mm_fault.patch
mm-handle-pud-faults-under-the-vma-lock.patch
mm-handle-some-pmd-faults-under-the-vma-lock.patch
mm-move-fault_flag_vma_lock-check-down-in-handle_pte_fault.patch
mm-move-fault_flag_vma_lock-check-down-from-do_fault.patch
mm-run-the-fault-around-code-under-the-vma-lock.patch
mm-handle-swap-and-numa-pte-faults-under-the-vma-lock.patch
mm-handle-faults-that-merely-update-the-accessed-bit-under-the-vma-lock.patch
