From: "Matthew Wilcox (Oracle)" willy@infradead.org
mainline inclusion from mainline-v6.10-rc1 commit 737019cf6ac5babb75645ad324aeead7bc04749d category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/I9R3AY CVE: NA
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...
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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 Signed-off-by: Liu Shixin liushixin2@huawei.com --- mm/memory.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-)
diff --git a/mm/memory.c b/mm/memory.c index 0a3e0f680f90..fa4d1b499511 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -3233,16 +3233,21 @@ 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; }
/*