From: Greg KH on
2.6.34-stable review patch. If anyone has any objections, please let us know.

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

From: Trond Myklebust <Trond.Myklebust(a)netapp.com>

commit b608b283a962caaa280756bc8563016a71712acf upstream.

See https://bugzilla.kernel.org/show_bug.cgi?id=16056

If other processes are blocked waiting for kswapd to free up some memory so
that they can make progress, then we cannot allow kswapd to block on those
processes.

Signed-off-by: Trond Myklebust <Trond.Myklebust(a)netapp.com>
Signed-off-by: Greg Kroah-Hartman <gregkh(a)suse.de>

---
fs/nfs/file.c | 13 +++++++++++--
fs/nfs/write.c | 4 ++--
include/linux/nfs_fs.h | 1 +
3 files changed, 14 insertions(+), 4 deletions(-)

--- a/fs/nfs/file.c
+++ b/fs/nfs/file.c
@@ -27,6 +27,7 @@
#include <linux/pagemap.h>
#include <linux/aio.h>
#include <linux/gfp.h>
+#include <linux/swap.h>

#include <asm/uaccess.h>
#include <asm/system.h>
@@ -489,11 +490,19 @@ static void nfs_invalidate_page(struct p
*/
static int nfs_release_page(struct page *page, gfp_t gfp)
{
+ struct address_space *mapping = page->mapping;
+
dfprintk(PAGECACHE, "NFS: release_page(%p)\n", page);

/* 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 (mapping && (gfp & GFP_KERNEL) == GFP_KERNEL) {
+ int how = FLUSH_SYNC;
+
+ /* Don't let kswapd deadlock waiting for OOM RPC calls */
+ if (current_is_kswapd())
+ how = 0;
+ nfs_commit_inode(mapping->host, how);
+ }
/* If PagePrivate() is set, then the page is not freeable */
if (PagePrivate(page))
return 0;
--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -1379,7 +1379,7 @@ static const struct rpc_call_ops nfs_com
.rpc_release = nfs_commit_release,
};

-static int nfs_commit_inode(struct inode *inode, int how)
+int nfs_commit_inode(struct inode *inode, int how)
{
LIST_HEAD(head);
int may_wait = how & FLUSH_SYNC;
@@ -1443,7 +1443,7 @@ out_mark_dirty:
return ret;
}
#else
-static int nfs_commit_inode(struct inode *inode, int how)
+int nfs_commit_inode(struct inode *inode, int how)
{
return 0;
}
--- a/include/linux/nfs_fs.h
+++ b/include/linux/nfs_fs.h
@@ -479,6 +479,7 @@ extern int nfs_wb_all(struct inode *inod
extern int nfs_wb_page(struct inode *inode, struct page* page);
extern int nfs_wb_page_cancel(struct inode *inode, struct page* page);
#if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
+extern int nfs_commit_inode(struct inode *, int);
extern struct nfs_write_data *nfs_commitdata_alloc(void);
extern void nfs_commit_free(struct nfs_write_data *wdata);
#endif


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