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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
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')
-rw-r--r--drivers/md/md.c29
-rw-r--r--drivers/md/raid1.c2
-rw-r--r--drivers/md/raid5.c3
3 files changed, 34 insertions, 0 deletions
diff --git a/drivers/md/md.c b/drivers/md/md.c
index ec3d8e8a0bd3..e8807ea5377d 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -3564,6 +3564,8 @@ static int get_bitmap_file(mddev_t * mddev, void __user * arg)
3564 char *ptr, *buf = NULL; 3564 char *ptr, *buf = NULL;
3565 int err = -ENOMEM; 3565 int err = -ENOMEM;
3566 3566
3567 md_allow_write(mddev);
3568
3567 file = kmalloc(sizeof(*file), GFP_KERNEL); 3569 file = kmalloc(sizeof(*file), GFP_KERNEL);
3568 if (!file) 3570 if (!file)
3569 goto out; 3571 goto out;
@@ -5032,6 +5034,33 @@ void md_write_end(mddev_t *mddev)
5032 } 5034 }
5033} 5035}
5034 5036
5037/* md_allow_write(mddev)
5038 * Calling this ensures that the array is marked 'active' so that writes
5039 * may proceed without blocking. It is important to call this before
5040 * attempting a GFP_KERNEL allocation while holding the mddev lock.
5041 * Must be called with mddev_lock held.
5042 */
5043void md_allow_write(mddev_t *mddev)
5044{
5045 if (!mddev->pers)
5046 return;
5047 if (mddev->ro)
5048 return;
5049
5050 spin_lock_irq(&mddev->write_lock);
5051 if (mddev->in_sync) {
5052 mddev->in_sync = 0;
5053 set_bit(MD_CHANGE_CLEAN, &mddev->flags);
5054 if (mddev->safemode_delay &&
5055 mddev->safemode == 0)
5056 mddev->safemode = 1;
5057 spin_unlock_irq(&mddev->write_lock);
5058 md_update_sb(mddev, 0);
5059 } else
5060 spin_unlock_irq(&mddev->write_lock);
5061}
5062EXPORT_SYMBOL_GPL(md_allow_write);
5063
5035static DECLARE_WAIT_QUEUE_HEAD(resync_wait); 5064static DECLARE_WAIT_QUEUE_HEAD(resync_wait);
5036 5065
5037#define SYNC_MARKS 10 5066#define SYNC_MARKS 10
diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index ab74d40cac98..97ee870b265d 100644
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -2104,6 +2104,8 @@ static int raid1_reshape(mddev_t *mddev)
2104 return -EINVAL; 2104 return -EINVAL;
2105 } 2105 }
2106 2106
2107 md_allow_write(mddev);
2108
2107 raid_disks = mddev->raid_disks + mddev->delta_disks; 2109 raid_disks = mddev->raid_disks + mddev->delta_disks;
2108 2110
2109 if (raid_disks < conf->raid_disks) { 2111 if (raid_disks < conf->raid_disks) {
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++;