On 26.04.24 16:45, Matthew Wilcox (Oracle) wrote:
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. Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx> Reviewed-by: Jann Horn <jannh@xxxxxxxxxx> Reviewed-by: Suren Baghdasaryan <surenb@xxxxxxxxxx> --- mm/memory.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) diff --git a/mm/memory.c b/mm/memory.c index 7dc112d3a7e4..b5453b86ec4b 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; }/*
Fancy Reviewed-by: David Hildenbrand <david@xxxxxxxxxx> -- Cheers, David / dhildenb
