On Tue, 2009-09-08 at 18:05 -0400, Chuck Lever wrote:
> Don't dive into memory reclaim in the NFS direct I/O paths, otherwise
> we can deadlock.
>
> Reported by: Wengang Wang <wen.gang.wang@xxxxxxxxxx>
> Fix-suggested-by: Zach Brown <zach.brown@xxxxxxxxxx>
> Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
Wait... What??? How does an O_DIRECT read or write allocation deadlock
with memory reclaim? Both the read and the write path call
nfs_direct_req_alloc() before they pin any user pages in memory.
Trond
> ---
>
> Trond-
>
> Thoughts?
>
> fs/nfs/direct.c | 2 +-
> 1 files changed, 1 insertions(+), 1 deletions(-)
>
> diff --git a/fs/nfs/direct.c b/fs/nfs/direct.c
> index e4e089a..00f06b8 100644
> --- a/fs/nfs/direct.c
> +++ b/fs/nfs/direct.c
> @@ -149,7 +149,7 @@ static inline struct nfs_direct_req *nfs_direct_req_alloc(void)
> {
> struct nfs_direct_req *dreq;
>
> - dreq = kmem_cache_alloc(nfs_direct_cachep, GFP_KERNEL);
> + dreq = kmem_cache_alloc(nfs_direct_cachep, GFP_NOFS);
> if (!dreq)
> return NULL;
>
>
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--
Trond Myklebust
Linux NFS client maintainer
NetApp
Trond.Myklebust@xxxxxxxxxx
www.netapp.com
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