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authorNeilBrown <neilb@suse.de>2007-01-26 03:57:11 -0500
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-01-26 16:51:00 -0500
commit2a2275d630b982e5f90206f9bc497f6695a3ec5d (patch)
tree88cddee709b2107b74e5424810d4ffb6e3772382 /drivers/md/raid5.c
parenta0ad13ef643a5829d63c456ab6143bbda60b44a9 (diff)
[PATCH] md: fix potential memalloc deadlock in md
If a GFP_KERNEL allocation is attempted in md while the mddev_lock is held, it is possible for a deadlock to eventuate. This happens if the array was marked 'clean', and the memalloc triggers a write-out to the md device. For the writeout to succeed, the array must be marked 'dirty', and that requires getting the mddev_lock. So, before attempting a GFP_KERNEL allocation while holding the lock, make sure the array is marked 'dirty' (unless it is currently read-only). Signed-off-by: Neil Brown <neilb@suse.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers/md/raid5.c')
-rw-r--r--drivers/md/raid5.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index be008f034ada..8a30b297ac3a 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -405,6 +405,8 @@ static int resize_stripes(raid5_conf_t *conf, int newsize)
405 if (newsize <= conf->pool_size) 405 if (newsize <= conf->pool_size)
406 return 0; /* never bother to shrink */ 406 return 0; /* never bother to shrink */
407 407
408 md_allow_write(conf->mddev);
409
408 /* Step 1 */ 410 /* Step 1 */
409 sc = kmem_cache_create(conf->cache_name[1-conf->active_name], 411 sc = kmem_cache_create(conf->cache_name[1-conf->active_name],
410 sizeof(struct stripe_head)+(newsize-1)*sizeof(struct r5dev), 412 sizeof(struct stripe_head)+(newsize-1)*sizeof(struct r5dev),
@@ -3250,6 +3252,7 @@ raid5_store_stripe_cache_size(mddev_t *mddev, const char *page, size_t len)
3250 else 3252 else
3251 break; 3253 break;
3252 } 3254 }
3255 md_allow_write(mddev);
3253 while (new > conf->max_nr_stripes) { 3256 while (new > conf->max_nr_stripes) {
3254 if (grow_one_stripe(conf)) 3257 if (grow_one_stripe(conf))
3255 conf->max_nr_stripes++; 3258 conf->max_nr_stripes++;