From ddeff520f02b92128132c282c350fa72afffb84a Mon Sep 17 00:00:00 2001
From: Nikita Danilov <nikita@clusterfs.com>
Date: Wed, 9 Aug 2006 13:53:47 -0400
Subject: NFS: Fix a potential deadlock in nfs_release_page
nfs_wb_page() waits on request completion and, as a result, is not safe to be
called from nfs_release_page() invoked by VM scanner as part of GFP_NOFS
allocation. Fix possible deadlock by analyzing gfp mask and refusing to
release page if __GFP_FS is not set.
Signed-off-by: Nikita Danilov <danilov@gmail.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
(cherry picked from 374d969debfb290bafcb41d28918dc6f7e43ce31 commit)
---
fs/nfs/file.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/fs/nfs/file.c b/fs/nfs/file.c
index cc2b874ad5a..48e892880d5 100644
--- a/fs/nfs/file.c
+++ b/fs/nfs/file.c
@@ -312,7 +312,13 @@ static void nfs_invalidate_page(struct page *page, unsigned long offset)
static int nfs_release_page(struct page *page, gfp_t gfp)
{
- return !nfs_wb_page(page->mapping->host, page);
+ if (gfp & __GFP_FS)
+ return !nfs_wb_page(page->mapping->host, page);
+ else
+ /*
+ * Avoid deadlock on nfs_wait_on_request().
+ */
+ return 0;
}
const struct address_space_operations nfs_file_aops = {
--
cgit