linux-kernel - [061/156] NFS: Prevent another deadlock in nfs_release

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Message-Id: <20100330224800.138245099@linux.site>
Date:	Tue, 30 Mar 2010 15:41:35 -0700
From:	Greg KH <gregkh@...e.de>
To:	linux-kernel@...r.kernel.org, stable@...nel.org
Cc:	stable-review@...nel.org, torvalds@...ux-foundation.org,
	akpm@...ux-foundation.org, alan@...rguk.ukuu.org.uk,
	Trond Myklebust <Trond.Myklebust@...app.com>,
	Greg Kroah-Hartman <gregkh@...e.de>
Subject: [061/156] NFS: Prevent another deadlock in nfs_release_page()

2.6.33-stable review patch.  If anyone has any objections, please let us know.

------------------

From: Trond Myklebust <Trond.Myklebust@...app.com>

commit d812e575822a2b7ab1a7cadae2571505ec6ec2bd upstream.

We should not attempt to free the page if __GFP_FS is not set. Otherwise we
can deadlock as per

  http://bugzilla.kernel.org/show_bug.cgi?id=15578

Signed-off-by: Trond Myklebust <Trond.Myklebust@...app.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de>

---
 fs/nfs/file.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/fs/nfs/file.c
+++ b/fs/nfs/file.c
@@ -486,7 +486,8 @@ static int nfs_release_page(struct page
 {
 	dfprintk(PAGECACHE, "NFS: release_page(%p)\n", page);
 
-	if (gfp & __GFP_WAIT)
+	/* Only do I/O if gfp is a superset of GFP_KERNEL */
+	if ((gfp & GFP_KERNEL) == GFP_KERNEL)
 		nfs_wb_page(page->mapping->host, page);
 	/* If PagePrivate() is set, then the page is not freeable */
 	if (PagePrivate(page))


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