+ mm-handle-write-faults-to-ro-pages-under-the-vma-lock.patch added to mm-unstable branch

[Andrew Morton <akpm@linux-foundation.org>]

The patch titled
     Subject: mm: handle write faults to RO pages under the VMA lock
has been added to the -mm mm-unstable branch.  Its filename is
     mm-handle-write-faults-to-ro-pages-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-write-faults-to-ro-pages-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@infradead.org>
Subject: mm: handle write faults to RO pages under the VMA lock
Date: Wed, 27 Sep 2023 06:25:04 +0100

I think this is a pretty rare occurrence, but for consistency handle
faults with the VMA lock held the same way that we handle other faults
with the VMA lock held.

Link: https://lkml.kernel.org/r/20230927052505.2855872-7-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/memory.c |   13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)

--- a/mm/memory.c~mm-handle-write-faults-to-ro-pages-under-the-vma-lock
+++ a/mm/memory.c
@@ -3304,10 +3304,9 @@ 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;
-		}
+		ret = vmf_maybe_unlock_vma(vmf);
+		if (ret)
+			return ret;
 
 		vmf->flags |= FAULT_FLAG_MKWRITE;
 		ret = vma->vm_ops->pfn_mkwrite(vmf);
@@ -3331,10 +3330,10 @@ 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) {
+		tmp = vmf_maybe_unlock_vma(vmf);
+		if (tmp) {
 			folio_put(folio);
-			vma_end_read(vmf->vma);
-			return VM_FAULT_RETRY;
+			return tmp;
 		}
 
 		tmp = do_page_mkwrite(vmf, folio);
_

Patches currently in -mm which might be from willy@infradead.org are

i915-limit-the-length-of-an-sg-list-to-the-requested-length.patch
mm-report-success-more-often-from-filemap_map_folio_range.patch
mm-abstract-moving-to-the-next-pfn.patch
mm-convert-dax-lock-unlock-page-to-lock-unlock-folio.patch
buffer-pass-gfp-flags-to-folio_alloc_buffers.patch
buffer-hoist-gfp-flags-from-grow_dev_page-to-__getblk_gfp.patch
buffer-hoist-gfp-flags-from-grow_dev_page-to-__getblk_gfp-fix.patch
ext4-use-bdev_getblk-to-avoid-memory-reclaim-in-readahead-path.patch
buffer-use-bdev_getblk-to-avoid-memory-reclaim-in-readahead-path.patch
buffer-convert-getblk_unmovable-and-__getblk-to-use-bdev_getblk.patch
buffer-convert-sb_getblk-to-call-__getblk.patch
ext4-call-bdev_getblk-from-sb_getblk_gfp.patch
buffer-remove-__getblk_gfp.patch
hugetlb-use-a-folio-in-free_hpage_workfn.patch
hugetlb-remove-a-few-calls-to-page_folio.patch
hugetlb-convert-remove_pool_huge_page-to-remove_pool_hugetlb_folio.patch
mm-make-lock_folio_maybe_drop_mmap-vma-lock-aware.patch
mm-call-wp_page_copy-under-the-vma-lock.patch
mm-handle-shared-faults-under-the-vma-lock.patch
mm-handle-cow-faults-under-the-vma-lock.patch
mm-handle-read-faults-under-the-vma-lock.patch
mm-handle-write-faults-to-ro-pages-under-the-vma-lock.patch