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| author |  Matthew Wilcox (Oracle) <willy@infradead.org>
| 2024-04-26 15:45:03 +0100 |
|---|---|---|
| committer |  Andrew Morton <akpm@linux-foundation.org>
| 2024-05-05 17:53:54 -0700 |
| commit | 737019cf6ac5babb75645ad324aeead7bc04749d (patch) | |
| tree | 5f5ddc7a9b895153e78dcadbd372631ead28d337 /mm/memory.c | |
| parent | mm: fix some minor per-VMA lock issues in userfaultfd (diff) | |
| download | linux-737019cf6ac5babb75645ad324aeead7bc04749d.tar.gz linux-737019cf6ac5babb75645ad324aeead7bc04749d.tar.bz2 linux-737019cf6ac5babb75645ad324aeead7bc04749d.zip | |
mm: optimise vmf_anon_prepare() for VMAs without an anon_vma
If the mmap_lock can be taken for read, we can call __anon_vma_prepare()
while holding it, saving ourselves a trip back through the fault handler.
Link: https://lkml.kernel.org/r/20240426144506.1290619-5-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Jann Horn <jannh@google.com>
Reviewed-by: Suren Baghdasaryan <surenb@google.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm/memory.c')
| -rw-r--r-- | mm/memory.c | 13 |
1 files changed, 9 insertions, 4 deletions
diff --git a/mm/memory.c b/mm/memory.c index b5f72ce569e6..eea6e4984eae 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -3232,16 +3232,21 @@ static inline vm_fault_t vmf_can_call_fault(const struct vm_fault *vmf) vm_fault_t vmf_anon_prepare(struct vm_fault *vmf) { struct vm_area_struct *vma = vmf->vma; + vm_fault_t ret = 0; if (likely(vma->anon_vma)) return 0; if (vmf->flags & FAULT_FLAG_VMA_LOCK) { - vma_end_read(vma); - return VM_FAULT_RETRY; + if (!mmap_read_trylock(vma->vm_mm)) { + vma_end_read(vma); + return VM_FAULT_RETRY; + } } if (__anon_vma_prepare(vma)) - return VM_FAULT_OOM; - return 0; + ret = VM_FAULT_OOM; + if (vmf->flags & FAULT_FLAG_VMA_LOCK) + mmap_read_unlock(vma->vm_mm); + return ret; } /* |