From: Jan Kara <jack@xxxxxxx> This patch has been added to the stable tree. If you have any objections, please let us know. =============== [ Upstream commit 0911d0041c22922228ca52a977d7b0b0159fee4b ] Some ->page_mkwrite handlers may return VM_FAULT_RETRY as its return code (GFS2 or Lustre can definitely do this). However VM_FAULT_RETRY from ->page_mkwrite is completely unhandled by the mm code and results in locking and writeably mapping the page which definitely is not what the caller wanted. Fix Lustre and block_page_mkwrite_ret() used by other filesystems (notably GFS2) to return VM_FAULT_NOPAGE instead which results in bailing out from the fault code, the CPU then retries the access, and we fault again effectively doing what the handler wanted. Link: http://lkml.kernel.org/r/20170203150729.15863-1-jack@xxxxxxx Signed-off-by: Jan Kara <jack@xxxxxxx> Reported-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx> Reviewed-by: Jinshan Xiong <jinshan.xiong@xxxxxxxxx> Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx> --- drivers/staging/lustre/lustre/llite/llite_mmap.c | 4 +--- include/linux/buffer_head.h | 4 +--- 2 files changed, 2 insertions(+), 6 deletions(-) diff --git a/drivers/staging/lustre/lustre/llite/llite_mmap.c b/drivers/staging/lustre/lustre/llite/llite_mmap.c index a90214bb84dd..7511b4dfdfe5 100644 --- a/drivers/staging/lustre/lustre/llite/llite_mmap.c +++ b/drivers/staging/lustre/lustre/llite/llite_mmap.c @@ -404,15 +404,13 @@ static int ll_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf) result = VM_FAULT_LOCKED; break; case -ENODATA: + case -EAGAIN: case -EFAULT: result = VM_FAULT_NOPAGE; break; case -ENOMEM: result = VM_FAULT_OOM; break; - case -EAGAIN: - result = VM_FAULT_RETRY; - break; default: result = VM_FAULT_SIGBUS; break; diff --git a/include/linux/buffer_head.h b/include/linux/buffer_head.h index e6797ded700e..696b6c44c564 100644 --- a/include/linux/buffer_head.h +++ b/include/linux/buffer_head.h @@ -236,12 +236,10 @@ static inline int block_page_mkwrite_return(int err) { if (err == 0) return VM_FAULT_LOCKED; - if (err == -EFAULT) + if (err == -EFAULT || err == -EAGAIN) return VM_FAULT_NOPAGE; if (err == -ENOMEM) return VM_FAULT_OOM; - if (err == -EAGAIN) - return VM_FAULT_RETRY; /* -ENOSPC, -EDQUOT, -EIO ... */ return VM_FAULT_SIGBUS; } -- 2.11.0