diff options
| author | NeilBrown <neilb@suse.de> | 2007-01-26 00:57:11 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@woody.linux-foundation.org> | 2007-01-26 13:51:00 -0800 |
| commit | 2a2275d630b982e5f90206f9bc497f6695a3ec5d (patch) | |
| tree | 88cddee709b2107b74e5424810d4ffb6e3772382 /drivers/md/raid5.c | |
| parent | a0ad13ef643a5829d63c456ab6143bbda60b44a9 (diff) | |
| download | lwn-2a2275d630b982e5f90206f9bc497f6695a3ec5d.tar.gz lwn-2a2275d630b982e5f90206f9bc497f6695a3ec5d.zip | |
[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.c | 3 |
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) if (newsize <= conf->pool_size) return 0; /* never bother to shrink */ + md_allow_write(conf->mddev); + /* Step 1 */ sc = kmem_cache_create(conf->cache_name[1-conf->active_name], 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) else break; } + md_allow_write(mddev); while (new > conf->max_nr_stripes) { if (grow_one_stripe(conf)) conf->max_nr_stripes++; |