2014-11-03 20:19:51

by Weston Andros Adamson

Subject: [PATCH] nfs: remove spurious WARN_ON_ONCE in write path

This WARN_ON_ONCE was supposed to catch reference counting bugs, but can
trigger in inappropriate situations.

This was reproducible using NFSv2 on an architecture with 64K pages -- we
verified that it was not a reference counting bug and the warning was
safe to ignore.

Reported-by: Will Deacon <[email protected]>
Tested-by: Will Deacon <[email protected]>
Signed-off-by: Weston Andros Adamson <[email protected]>
---
fs/nfs/write.c | 2 --
1 file changed, 2 deletions(-)

diff --git a/fs/nfs/write.c b/fs/nfs/write.c
index 12493846a2d3..f83b02dc9166 100644
--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -715,8 +715,6 @@ static void nfs_inode_remove_request(struct nfs_page *req)

if (test_and_clear_bit(PG_INODE_REF, &req->wb_flags))
nfs_release_request(req);
- else
- WARN_ON_ONCE(1);
}

static void
--
1.9.3 (Apple Git-50)

2014-11-03 20:21:15

by Weston Andros Adamson

Subject: Re: [PATCH] nfs: remove spurious WARN_ON_ONCE in write path

I’m not sure it we want to CC stable on this one - the single warning can simply be ignored.

-dros

> On Nov 3, 2014, at 3:19 PM, Weston Andros Adamson <[email protected]> wrote:
>
> This WARN_ON_ONCE was supposed to catch reference counting bugs, but can
> trigger in inappropriate situations.
>
> This was reproducible using NFSv2 on an architecture with 64K pages -- we
> verified that it was not a reference counting bug and the warning was
> safe to ignore.
>
> Reported-by: Will Deacon <[email protected]>
> Tested-by: Will Deacon <[email protected]>
> Signed-off-by: Weston Andros Adamson <[email protected]>
> ---
> fs/nfs/write.c | 2 --
> 1 file changed, 2 deletions(-)
>
> diff --git a/fs/nfs/write.c b/fs/nfs/write.c
> index 12493846a2d3..f83b02dc9166 100644
> --- a/fs/nfs/write.c
> +++ b/fs/nfs/write.c
> @@ -715,8 +715,6 @@ static void nfs_inode_remove_request(struct nfs_page *req)
>
> if (test_and_clear_bit(PG_INODE_REF, &req->wb_flags))
> nfs_release_request(req);
> - else
> - WARN_ON_ONCE(1);
> }
>
> static void
> --
> 1.9.3 (Apple Git-50)
>