diff options
| author | NeilBrown <neilb@suse.de> | 2007-01-25 15:35:34 +1100 |
|---|---|---|
| committer | Chris Wright <chrisw@sous-sol.org> | 2007-02-05 08:31:43 -0800 |
| commit | ec803d270172c7329be48faf49ff3095a54c4a56 (patch) | |
| tree | 2711ba33b1fc0cc13ab78d934100f2319d5be137 | |
| parent | 50c524829e518ca5a7e3e5423726e6bb24afaac4 (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 alloction 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: Chris Wright <chrisw@sous-sol.org>
| -rw-r--r-- | drivers/md/md.c | 29 | ||||
| -rw-r--r-- | drivers/md/raid1.c | 2 | ||||
| -rw-r--r-- | drivers/md/raid5.c | 3 | ||||
| -rw-r--r-- | include/linux/raid/md.h | 2 |
4 files changed, 35 insertions, 1 deletions
diff --git a/drivers/md/md.c b/drivers/md/md.c index 213f606ef5fd..f2789e6fcfa3 100644 --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -3561,6 +3561,8 @@ static int get_bitmap_file(mddev_t * mddev, void __user * arg) char *ptr, *buf = NULL; int err = -ENOMEM; + md_allow_write(mddev); + file = kmalloc(sizeof(*file), GFP_KERNEL); if (!file) goto out; @@ -5029,6 +5031,33 @@ void md_write_end(mddev_t *mddev) } } +/* md_allow_write(mddev) + * Calling this ensures that the array is marked 'active' so that writes + * may proceed without blocking. It is important to call this before + * attempting a GFP_KERNEL allocation while holding the mddev lock. + * Must be called with mddev_lock held. + */ +void md_allow_write(mddev_t *mddev) +{ + if (!mddev->pers) + return; + if (mddev->ro) + return; + + spin_lock_irq(&mddev->write_lock); + if (mddev->in_sync) { + mddev->in_sync = 0; + set_bit(MD_CHANGE_CLEAN, &mddev->flags); + if (mddev->safemode_delay && + mddev->safemode == 0) + mddev->safemode = 1; + spin_unlock_irq(&mddev->write_lock); + md_update_sb(mddev, 0); + } else + spin_unlock_irq(&mddev->write_lock); +} +EXPORT_SYMBOL_GPL(md_allow_write); + static DECLARE_WAIT_QUEUE_HEAD(resync_wait); #define SYNC_MARKS 10 diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c index 77b19b4d0a11..64bd5a79f902 100644 --- a/drivers/md/raid1.c +++ b/drivers/md/raid1.c @@ -2104,6 +2104,8 @@ static int raid1_reshape(mddev_t *mddev) return -EINVAL; } + md_allow_write(mddev); + raid_disks = mddev->raid_disks + mddev->delta_disks; if (raid_disks < conf->raid_disks) { diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c index 69c3e201fa3b..c1a4bda0779d 100644 --- a/drivers/md/raid5.c +++ b/drivers/md/raid5.c @@ -403,6 +403,8 @@ 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), @@ -3045,6 +3047,7 @@ 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++; diff --git a/include/linux/raid/md.h b/include/linux/raid/md.h index 866a1e2b0ce0..fbaeda79b2e9 100644 --- a/include/linux/raid/md.h +++ b/include/linux/raid/md.h @@ -94,7 +94,7 @@ extern int sync_page_io(struct block_device *bdev, sector_t sector, int size, struct page *page, int rw); extern void md_do_sync(mddev_t *mddev); extern void md_new_event(mddev_t *mddev); - +extern void md_allow_write(mddev_t *mddev); #endif /* CONFIG_MD */ #endif |