linux-kernel - [PATCH] fix creating zero sized bio mempools in low memory system

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Message-ID: <44FC1C90.200@redhat.com>
Date:	Mon, 04 Sep 2006 14:31:12 +0200
From:	Milan Broz <mbroz@...hat.com>
To:	linux-kernel@...r.kernel.org
CC:	Andrew Morton <akpm@...l.org>, Jens Axboe <axboe@...e.de>
Subject: [PATCH] fix creating zero sized bio mempools in low memory system

In the very low memory systems is in the init_bio call
scale parameter set to zero and it leads to creating
zero sized mempool.

This patch prevents pool_entries parameter become zero,
so the created pool have at least 1 entry.

Mempool with 0 entries lead to incorrect behaviour 
of mempool_free. (Alloc requests are not waken up
and system stalls in mempool_alloc->ioschedule). 


Signed-off-by: Milan Broz <mbroz@...hat.com>

Index: linux-2.6.18-rc6/fs/bio.c
===================================================================
--- linux-2.6.18-rc6.orig/fs/bio.c
+++ linux-2.6.18-rc6/fs/bio.c
@@ -1142,7 +1142,7 @@ static int biovec_create_pools(struct bi
 		struct biovec_slab *bp = bvec_slabs + i;
 		mempool_t **bvp = bs->bvec_pools + i;
 
-		if (i >= scale)
+		if (pool_entries > 1 && i >= scale)
 			pool_entries >>= 1;
 
 		*bvp = mempool_create_slab_pool(pool_entries, bp->slab);



-- 
VGER BF report: U 0.493705
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