2020-04-28 07:22:03

by Wei Yongjun

Subject: [PATCH -next] NFSv4: Use GFP_ATOMIC under spin lock in _pnfs_grab_empty_layout()

A spin lock is taken here so we should use GFP_ATOMIC.

Signed-off-by: Wei Yongjun <[email protected]>
---
fs/nfs/pnfs.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/nfs/pnfs.c b/fs/nfs/pnfs.c
index dd2e14f5875d..d84c1b7b71d2 100644
--- a/fs/nfs/pnfs.c
+++ b/fs/nfs/pnfs.c
@@ -2170,7 +2170,7 @@ _pnfs_grab_empty_layout(struct inode *ino, struct nfs_open_context *ctx)
struct pnfs_layout_hdr *lo;

spin_lock(&ino->i_lock);
- lo = pnfs_find_alloc_layout(ino, ctx, GFP_KERNEL);
+ lo = pnfs_find_alloc_layout(ino, ctx, GFP_ATOMIC);
if (!lo)
goto out_unlock;
if (!test_bit(NFS_LAYOUT_INVALID_STID, &lo->plh_flags))

2020-04-28 17:44:13

by Trond Myklebust

Subject: Re: [PATCH -next] NFSv4: Use GFP_ATOMIC under spin lock in _pnfs_grab_empty_layout()

On Tue, 2020-04-28 at 07:19 +0000, Wei Yongjun wrote:
> A spin lock is taken here so we should use GFP_ATOMIC.
>
> Signed-off-by: Wei Yongjun <[email protected]>
> ---
> fs/nfs/pnfs.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/fs/nfs/pnfs.c b/fs/nfs/pnfs.c
> index dd2e14f5875d..d84c1b7b71d2 100644
> --- a/fs/nfs/pnfs.c
> +++ b/fs/nfs/pnfs.c
> @@ -2170,7 +2170,7 @@ _pnfs_grab_empty_layout(struct inode *ino,
> struct nfs_open_context *ctx)
> struct pnfs_layout_hdr *lo;
>
> spin_lock(&ino->i_lock);
> - lo = pnfs_find_alloc_layout(ino, ctx, GFP_KERNEL);
> + lo = pnfs_find_alloc_layout(ino, ctx, GFP_ATOMIC);
> if (!lo)
> goto out_unlock;
> if (!test_bit(NFS_LAYOUT_INVALID_STID, &lo->plh_flags))
>
>
>

NACK. There is no allocation under the spinlock.

--
Trond Myklebust
Linux NFS client maintainer, Hammerspace
[email protected]

2020-04-28 18:08:47

by Dan Carpenter

Subject: Re: [PATCH -next] NFSv4: Use GFP_ATOMIC under spin lock in _pnfs_grab_empty_layout()

On Tue, Apr 28, 2020 at 07:19:32AM +0000, Wei Yongjun wrote:
> A spin lock is taken here so we should use GFP_ATOMIC.
>
> Signed-off-by: Wei Yongjun <[email protected]>
> ---
> fs/nfs/pnfs.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/fs/nfs/pnfs.c b/fs/nfs/pnfs.c
> index dd2e14f5875d..d84c1b7b71d2 100644
> --- a/fs/nfs/pnfs.c
> +++ b/fs/nfs/pnfs.c
> @@ -2170,7 +2170,7 @@ _pnfs_grab_empty_layout(struct inode *ino, struct nfs_open_context *ctx)
> struct pnfs_layout_hdr *lo;
>
> spin_lock(&ino->i_lock);
^^^
> - lo = pnfs_find_alloc_layout(ino, ctx, GFP_KERNEL);
> + lo = pnfs_find_alloc_layout(ino, ctx, GFP_ATOMIC);
^^^
It releases the lock before allocating. It's annotated.

regards,
dan carpenter

2020-04-29 01:04:57

by Wei Yongjun

Subject: Re: [PATCH -next] NFSv4: Use GFP_ATOMIC under spin lock in _pnfs_grab_empty_layout()

On 2020/4/29 2:04, Dan Carpenter wrote:
> On Tue, Apr 28, 2020 at 07:19:32AM +0000, Wei Yongjun wrote:
>> A spin lock is taken here so we should use GFP_ATOMIC.
>>
>> Signed-off-by: Wei Yongjun <[email protected]>
>> ---
>> fs/nfs/pnfs.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/fs/nfs/pnfs.c b/fs/nfs/pnfs.c
>> index dd2e14f5875d..d84c1b7b71d2 100644
>> --- a/fs/nfs/pnfs.c
>> +++ b/fs/nfs/pnfs.c
>> @@ -2170,7 +2170,7 @@ _pnfs_grab_empty_layout(struct inode *ino, struct nfs_open_context *ctx)
>> struct pnfs_layout_hdr *lo;
>>
>> spin_lock(&ino->i_lock);
> ^^^
>> - lo = pnfs_find_alloc_layout(ino, ctx, GFP_KERNEL);
>> + lo = pnfs_find_alloc_layout(ino, ctx, GFP_ATOMIC);
> ^^^
> It releases the lock before allocating. It's annotated.
>

Got it, thanks.

regards,
Wei Yongjun