diff --git a/mm/internal.h b/mm/internal.h index 386ad27a8aa06381e5f7af62ef55620afcb0984e..47ae16a79b6cbe4b814f8050a5317a47493b31ec 100644 --- a/mm/internal.h +++ b/mm/internal.h @@ -354,6 +354,27 @@ vma_address(struct page *page, struct vm_area_struct *vma) return max(start, vma->vm_start); } +static inline struct file *maybe_unlock_mmap_for_io(struct vm_fault *vmf, + struct file *fpin) +{ + int flags = vmf->flags; + + if (fpin) + return fpin; + + /* + * FAULT_FLAG_RETRY_NOWAIT means we don't want to wait on page locks or + * anything, so we only pin the file and drop the mmap_sem if only + * FAULT_FLAG_ALLOW_RETRY is set. + */ + if ((flags & (FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_RETRY_NOWAIT)) == + FAULT_FLAG_ALLOW_RETRY) { + fpin = get_file(vmf->vma->vm_file); + up_read(&vmf->vma->vm_mm->mmap_sem); + } + return fpin; +} + #else /* !CONFIG_MMU */ static inline void clear_page_mlock(struct page *page) { } static inline void mlock_vma_page(struct page *page) { } diff --git a/mm/shmem.c b/mm/shmem.c index 5b93877c20f183ca0b9f42bfc4327a1c2394a332..27b3fdd0d970677feb592b036debea0cbd5093eb 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -2017,16 +2017,14 @@ static vm_fault_t shmem_fault(struct vm_fault *vmf) shmem_falloc->waitq && vmf->pgoff >= shmem_falloc->start && vmf->pgoff < shmem_falloc->next) { + struct file *fpin; wait_queue_head_t *shmem_falloc_waitq; DEFINE_WAIT_FUNC(shmem_fault_wait, synchronous_wake_function); ret = VM_FAULT_NOPAGE; - if ((vmf->flags & FAULT_FLAG_ALLOW_RETRY) && - !(vmf->flags & FAULT_FLAG_RETRY_NOWAIT)) { - /* It's polite to up mmap_sem if we can */ - up_read(&vma->vm_mm->mmap_sem); + fpin = maybe_unlock_mmap_for_io(vmf, NULL); + if (fpin) ret = VM_FAULT_RETRY; - } shmem_falloc_waitq = shmem_falloc->waitq; prepare_to_wait(shmem_falloc_waitq, &shmem_fault_wait, @@ -2044,6 +2042,9 @@ static vm_fault_t shmem_fault(struct vm_fault *vmf) spin_lock(&inode->i_lock); finish_wait(shmem_falloc_waitq, &shmem_fault_wait); spin_unlock(&inode->i_lock); + + if (fpin) + fput(fpin); return ret; } spin_unlock(&inode->i_lock);