On Sat, Aug 22, 2015 at 9:17 PM, Nicholas Krause <[email protected]> wrote:
>
> This fixes a possible deadlock occurrence issue on the error path
> in the function nfs_vm_page_mkwrite for checking if the calls to
> the functions nfs_flus_incompatible and nfs_updatepage have failed
> by incorrectly not jumping to the correct goto label out_unlock
> for unlocking the locked structure page pointer thus causing a
> deadlock due to not correctly unlocking the internal structure
> page pointer used by the function nfs_vm_page_mkwrite that had
> been previously locked with the function lock_page. Further more
> we also remove the goto label out as no error paths in this function
> now use this label and this label should be removed to avoid build
> warnings related to having a undefined label.
>
> Signed-off-by: Nicholas Krause <[email protected]>
> ---
> fs/nfs/file.c | 3 +--
> 1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/fs/nfs/file.c b/fs/nfs/file.c
> index cc4fa1e..fe68ecc 100644
> --- a/fs/nfs/file.c
> +++ b/fs/nfs/file.c
> @@ -629,12 +629,11 @@ static int nfs_vm_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
> ret = VM_FAULT_LOCKED;
> if (nfs_flush_incompatible(filp, page) == 0 &&
> nfs_updatepage(filp, page, 0, pagelen) == 0)
> - goto out;
> + goto out_unlock;
>
> ret = VM_FAULT_SIGBUS;
> out_unlock:
> unlock_page(page);
> -out:
> return ret;
> }
>
>
That's the success path that you are modifying, not the error path.
Furthermore, the return value is still VM_FAULT_LOCKED, which means
the caller expects the page to be returned in the locked state.
So NACK....
Trond