From: Trond Myklebust <Trond.Myklebust@netapp.com>
Date: Fri, 19 Mar 2010 17:55:17 +0000 (-0400)
Subject: NFS: Prevent another deadlock in nfs_release_page()
X-Git-Tag: firefly_0821_release~10186^2~1972
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=0b4d9d6ac1f1d22fb0342305cd1e9bf67307d194;p=firefly-linux-kernel-4.4.55.git

NFS: Prevent another deadlock in nfs_release_page()

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@netapp.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---

diff --git a/fs/nfs/file.c b/fs/nfs/file.c
index 393d40fd7eb9..61b3bf503ee1 100644
--- a/fs/nfs/file.c
+++ b/fs/nfs/file.c
@@ -486,7 +486,8 @@ static int nfs_release_page(struct page *page, gfp_t gfp)
 {
 	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))