From: Larry Woodman <lwoodman@redhat.com>
Date: Tue, 29 Sep 2009 15:50:26 -0400
Subject: [mm] prevent tmpfs from going readonly during oom kills
Message-id: <1254239426.3219.15.camel@dhcp-100-19-198.bos.redhat.com>
Patchwork-id: 20984
O-Subject: [RHEL5-U5 Patch] Prevent the tmpfs filesystem from going to
	readonly mode during OOM kills
Bugzilla: 497257
RH-Acked-by: Dean Nelson <dnelson@redhat.com>
RH-Acked-by: Jiri Olsa <jolsa@redhat.com>
RH-Acked-by: Rik van Riel <riel@redhat.com>

Back In RHEL5-02 I changed __alloc_pages() so it would not call
try_to_free_pages() if the process was being OOM killed in
linux-2.6-mm-oom-prevent-from-killing-several-processes.patch.

If a process calls __alloc_pages() with __GFP_NOFAIL we cant bail
and return NULL because thing like tmpfs filesystem going to readonly
mode can occur.

The following upstream patch fixed this problem by not bailing out of
__alloc_pages when the process is being OOM killed if __GFP_NOFAIL was
passed in.

Fixes BZ 497257

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index cddb8ce..fd53e96 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1015,7 +1015,7 @@ nofail_alloc:
 		goto nopage;
 
 rebalance:
-	if (test_thread_flag(TIF_MEMDIE) || would_oom_kill)
+	if (test_thread_flag(TIF_MEMDIE) && !(gfp_mask & __GFP_NOFAIL) || would_oom_kill)
 		goto nopage;
 	cond_resched();