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| author | Matthew Wilcox (Oracle) <willy@infradead.org> | 2024-04-26 15:45:00 +0100 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2024-05-05 17:53:53 -0700 |
| commit | 3be51060599ff01899b6d8c3f8aca456506cf5ea (patch) | |
| tree | 0a684360bd4979d6554b317575e1e4d3827fbed4 /mm/rmap.c | |
| parent | e0ffb29bc54d86b9ab10ebafc66eb1b7229e0cd7 (diff) | |
| download | linux-3be51060599ff01899b6d8c3f8aca456506cf5ea.tar.gz linux-3be51060599ff01899b6d8c3f8aca456506cf5ea.tar.bz2 linux-3be51060599ff01899b6d8c3f8aca456506cf5ea.zip | |
mm: assert the mmap_lock is held in __anon_vma_prepare()
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@intel.com/
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@infradead.org
Link: https://lkml.kernel.org/r/20240426144506.1290619-2-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Suren Baghdasaryan <surenb@google.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: Jann Horn <jannh@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm/rmap.c')
| -rw-r--r-- | mm/rmap.c | 3 |
1 files changed, 1 insertions, 2 deletions
diff --git a/mm/rmap.c b/mm/rmap.c index 2608c40dffad..619d4d65d99b 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -182,8 +182,6 @@ static void anon_vma_chain_link(struct vm_area_struct *vma, * 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_struct *vma) struct anon_vma *anon_vma, *allocated; struct anon_vma_chain *avc; + mmap_assert_locked(mm); might_sleep(); avc = anon_vma_chain_alloc(GFP_KERNEL); |