android/android_kernel_samsung_sm8650
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

BACKPORT: FROMGIT: mm: handle faults that merely update the accessed bit under the VMA lock

Browse Source 
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@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>

(cherry picked from commit 88e2667632d43928d3ed50d0163ecd73aaa2d455
https: //git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-unstable)
[surenb: replaced folio_put() with put_page() in wp_page_shared()]

Bug: 293665307
Change-Id: I27ac40bb0f7347083f641e0cfc8ab33e182c4c5b
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
This commit is contained in:
Matthew Wilcox (Oracle) 2023-07-24 19:54:10 +01:00 committed by Suren Baghdasaryan
parent 9e066d4b35
commit 3ebafb7b46
1 changed files with 11 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

17
mm/memory.c
View File

@ -3314,6 +3314,11 @@ 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))
@ -3336,6 +3341,12 @@ static vm_fault_t wp_page_shared(struct vm_fault *vmf)
vm_fault_t tmp;
pte_unmap_unlock(vmf->pte, vmf->ptl);
if (vmf->flags & FAULT_FLAG_VMA_LOCK) {
put_page(vmf->page);
vma_end_read(vmf->vma);
return VM_FAULT_RETRY;
}
tmp = do_page_mkwrite(vmf);
if (unlikely(!tmp || (tmp &
(VM_FAULT_ERROR | VM_FAULT_NOPAGE)))) {
@ -5046,12 +5057,6 @@ 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;
}
vmf->ptl = pte_lockptr(vmf->vma->vm_mm, vmf->pmd);
spin_lock(vmf->ptl);
entry = vmf->orig_pte;