Messages in this thread Patch in this message | | | From | alexander.levin@verizon ... | Subject | [PATCH AUTOSEL for 4.4 15/17] mm: avoid returning VM_FAULT_RETRY from ->page_mkwrite handlers | Date | Wed, 22 Nov 2017 22:24:24 +0000 |
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From: Jan Kara <jack@suse.cz>
[ 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@suse.cz Signed-off-by: Jan Kara <jack@suse.cz> Reported-by: Al Viro <viro@ZenIV.linux.org.uk> Reviewed-by: Jinshan Xiong <jinshan.xiong@intel.com> Cc: Matthew Wilcox <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Sasha Levin <alexander.levin@verizon.com> --- 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 7df978371c9a..44fffbd1bc74 100644 --- a/drivers/staging/lustre/lustre/llite/llite_mmap.c +++ b/drivers/staging/lustre/lustre/llite/llite_mmap.c @@ -402,15 +402,13 @@ 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 89d9aa9e79bf..6fe974dbe741 100644 --- a/include/linux/buffer_head.h +++ b/include/linux/buffer_head.h @@ -234,12 +234,10 @@ 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
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