linux-kernel - [RFC PATCH] slab: __GFP_NOWARN not being propagated from mempool

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Message-Id: <E1L4jMt-0006OW-5J@pomaz-ex.szeredi.hu>
Date:	Mon, 24 Nov 2008 22:53:19 +0100
From:	Miklos Szeredi <miklos@...redi.hu>
To:	linux-mm@...ck.org
CC:	cl@...ux-foundation.org, penberg@...helsinki.fi,
	david@...morbit.com, peterz@...radead.org,
	linux-kernel@...r.kernel.org
Subject: [RFC PATCH] slab: __GFP_NOWARN not being propagated from mempool_alloc()

We see page allocation failure warnings on the mempool_alloc() path.
See this lkml posting for example:

http://lkml.org/lkml/2008/10/27/100

The cause is that on NUMA, alloc_slabmgmt() clears __GFP_NOWARN,
together with __GFP_THISNODE and __GFP_NORETRY.  But AFAICS it really
only wants to clear __GFP_THISNODE.

Does this patch looks good?

Warning: it's completely untested.

Miklos
---
 mm/slab.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

Index: linux-2.6/mm/slab.c
===================================================================
--- linux-2.6.orig/mm/slab.c	2008-10-24 12:40:34.000000000 +0200
+++ linux-2.6/mm/slab.c	2008-11-24 22:17:04.000000000 +0100
@@ -2609,7 +2609,8 @@ static struct slab *alloc_slabmgmt(struc
 	if (OFF_SLAB(cachep)) {
 		/* Slab management obj is off-slab. */
 		slabp = kmem_cache_alloc_node(cachep->slabp_cache,
-					      local_flags & ~GFP_THISNODE, nodeid);
+					      local_flags & ~__GFP_THISNODE,
+					      nodeid);
 		if (!slabp)
 			return NULL;
 	} else {
--
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