The quilt patch titled
Subject: mm: assert the mmap_lock is held in __anon_vma_prepare()
has been removed from the -mm tree. Its filename was
mm-assert-the-mmap_lock-is-held-in-__anon_vma_prepare.patch
This patch was dropped because it was merged into the mm-stable branch
of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
------------------------------------------------------
From: "Matthew Wilcox (Oracle)" <willy@xxxxxxxxxxxxx>
Subject: mm: assert the mmap_lock is held in __anon_vma_prepare()
Date: Fri, 26 Apr 2024 15:45:00 +0100
Patch series "Improve anon_vma scalability for anon VMAs".
We have a 3x throughput improvement reported by Intel's kernel test robot:
https://lore.kernel.org/all/202404261055.c5e24608-oliver.sang@xxxxxxxxx/
This is from delaying taking the mmap_lock for page faults until we
actually need the mmap_lock in order to assign an anon_vma to the vma. It
cleans up the page fault path a little by making the anon fault handler
more similar to the file fault handler.
This patch (of 4):
Convert the comment into an assertion.
Link: https://lkml.kernel.org/r/20240426144506.1290619-1-willy@xxxxxxxxxxxxx
Link: https://lkml.kernel.org/r/20240426144506.1290619-2-willy@xxxxxxxxxxxxx
Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Reviewed-by: Suren Baghdasaryan <surenb@xxxxxxxxxx>
Reviewed-by: David Hildenbrand <david@xxxxxxxxxx>
Cc: Jann Horn <jannh@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/rmap.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
--- a/mm/rmap.c~mm-assert-the-mmap_lock-is-held-in-__anon_vma_prepare
+++ a/mm/rmap.c
@@ -182,8 +182,6 @@ static void anon_vma_chain_link(struct v
* for the new allocation. At the same time, we do not want
* to do any locking for the common case of already having
* an anon_vma.
- *
- * This must be called with the mmap_lock held for reading.
*/
int __anon_vma_prepare(struct vm_area_struct *vma)
{
@@ -191,6 +189,7 @@ int __anon_vma_prepare(struct vm_area_st
struct anon_vma *anon_vma, *allocated;
struct anon_vma_chain *avc;
+ mmap_assert_locked(mm);
might_sleep();
avc = anon_vma_chain_alloc(GFP_KERNEL);
_
Patches currently in -mm which might be from willy@xxxxxxxxxxxxx are
squashfs-convert-squashfs_symlink_read_folio-to-use-folio-apis.patch
squashfs-remove-calls-to-set-the-folio-error-flag.patch
nilfs2-remove-calls-to-folio_set_error-and-folio_clear_error.patch
