+ mm-handle-cow-faults-under-the-vma-lock.patch added to mm-unstable branch

+ mm-handle-cow-faults-under-the-vma-lock.patch added to mm-unstable branch

[Andrew Morton]

The patch titled
     Subject: mm: handle COW faults under the VMA lock
has been added to the -mm mm-unstable branch.  Its filename is
     mm-handle-cow-faults-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-cow-faults-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

Before you just go and hit "reply", please:
   a) Consider who else should be cc'ed
   b) Prefer to cc a suitable mailing list as well
   c) Ideally: find the original patch on the mailing list and do a
      reply-to-all to that, adding suitable additional cc's

*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***

The -mm tree is included into linux-next via the mm-everything
branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there every 2-3 working days

------------------------------------------------------
From: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Subject: mm: handle COW faults under the VMA lock
Date: Wed, 27 Sep 2023 06:25:02 +0100

If the page is not currently present in the page tables, we need to call
the page fault handler to find out which page we're supposed to COW, so we
need to both check that there is already an anon_vma and that the fault
handler doesn't need the mmap_lock.

Link: https://lkml.kernel.org/r/20230927052505.2855872-5-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 |   12 +++++-------
 1 file changed, 5 insertions(+), 7 deletions(-)

--- a/mm/memory.c~mm-handle-cow-faults-under-the-vma-lock
+++ a/mm/memory.c
@@ -4642,13 +4642,11 @@ static vm_fault_t do_cow_fault(struct vm
 	struct vm_area_struct *vma = vmf->vma;
 	vm_fault_t ret;
 
-	if (vmf->flags & FAULT_FLAG_VMA_LOCK) {
-		vma_end_read(vma);
-		return VM_FAULT_RETRY;
-	}
-
-	if (unlikely(anon_vma_prepare(vma)))
-		return VM_FAULT_OOM;
+	ret = vmf_maybe_unlock_vma(vmf);
+	if (!ret)
+		ret = vmf_anon_prepare(vmf);
+	if (ret)
+		return ret;
 
 	vmf->cow_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, vmf->address);
 	if (!vmf->cow_page)
_

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

+ mm-handle-cow-faults-under-the-vma-lock.patch added to mm-unstable branch

[Andrew Morton]

The patch titled
     Subject: mm: handle COW faults under the VMA lock
has been added to the -mm mm-unstable branch.  Its filename is
     mm-handle-cow-faults-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-cow-faults-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

Before you just go and hit "reply", please:
   a) Consider who else should be cc'ed
   b) Prefer to cc a suitable mailing list as well
   c) Ideally: find the original patch on the mailing list and do a
      reply-to-all to that, adding suitable additional cc's

*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***

The -mm tree is included into linux-next via the mm-everything
branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there every 2-3 working days

------------------------------------------------------
From: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Subject: mm: handle COW faults under the VMA lock
Date: Fri, 6 Oct 2023 20:53:16 +0100

If the page is not currently present in the page tables, we need to call
the page fault handler to find out which page we're supposed to COW, so we
need to both check that there is already an anon_vma and that the fault
handler doesn't need the mmap_lock.

Link: https://lkml.kernel.org/r/20231006195318.4087158-5-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 |   12 +++++-------
 1 file changed, 5 insertions(+), 7 deletions(-)

--- a/mm/memory.c~mm-handle-cow-faults-under-the-vma-lock
+++ a/mm/memory.c
@@ -4642,13 +4642,11 @@ static vm_fault_t do_cow_fault(struct vm
 	struct vm_area_struct *vma = vmf->vma;
 	vm_fault_t ret;
 
-	if (vmf->flags & FAULT_FLAG_VMA_LOCK) {
-		vma_end_read(vma);
-		return VM_FAULT_RETRY;
-	}
-
-	if (unlikely(anon_vma_prepare(vma)))
-		return VM_FAULT_OOM;
+	ret = vmf_can_call_fault(vmf);
+	if (!ret)
+		ret = vmf_anon_prepare(vmf);
+	if (ret)
+		return ret;
 
 	vmf->cow_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, vmf->address);
 	if (!vmf->cow_page)
_

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

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
iomap-hold-state_lock-over-call-to-ifs_set_range_uptodate.patch
iomap-protect-read_bytes_pending-with-the-state_lock.patch
mm-add-folio_end_read.patch
ext4-use-folio_end_read.patch
buffer-use-folio_end_read.patch
iomap-use-folio_end_read.patch
bitops-add-xor_unlock_is_negative_byte.patch
alpha-implement-xor_unlock_is_negative_byte.patch
m68k-implement-xor_unlock_is_negative_byte.patch
mips-implement-xor_unlock_is_negative_byte.patch
powerpc-implement-arch_xor_unlock_is_negative_byte-on-32-bit.patch
riscv-implement-xor_unlock_is_negative_byte.patch
s390-implement-arch_xor_unlock_is_negative_byte.patch
mm-delete-checks-for-xor_unlock_is_negative_byte.patch
mm-add-folio_xor_flags_has_waiters.patch
mm-make-__end_folio_writeback-return-void.patch
mm-use-folio_xor_flags_has_waiters-in-folio_end_writeback.patch