diff options
| author | Mike Snitzer <snitzer@redhat.com> | 2012-05-12 01:43:16 +0100 |
|---|---|---|
| committer | Alasdair G Kergon <agk@redhat.com> | 2012-05-12 01:43:16 +0100 |
| commit | c3a0ce2eab76daf9516c817c3f227ea3f4549bd8 (patch) | |
| tree | c2510a2e8a4a0f2c0eb66f736d1e1b70b53d0e27 | |
| parent | 03aaae7cdc71bc306888440b1f569d463e917b6d (diff) | |
dm thin: fix unprotected use of prepared_discards list
Fix two places in commit 104655fd4dce ("dm thin: support discards") that
didn't use pool->lock to protect against concurrent changes to the
prepared_discards list.
Without this fix, thin_endio() can race with process_discard(), leading
to concurrent list_add()s that result in the processes locking up with
an error like the following:
WARNING: at lib/list_debug.c:32 __list_add+0x8f/0xa0()
...
list_add corruption. next->prev should be prev (ffff880323b96140), but was ffff8801d2c48440. (next=ffff8801d2c485c0).
...
Pid: 17205, comm: kworker/u:1 Tainted: G W O 3.4.0-rc3.snitm+ #1
Call Trace:
[<ffffffff8103ca1f>] warn_slowpath_common+0x7f/0xc0
[<ffffffff8103cb16>] warn_slowpath_fmt+0x46/0x50
[<ffffffffa04f6ce6>] ? bio_detain+0xc6/0x210 [dm_thin_pool]
[<ffffffff8124ff3f>] __list_add+0x8f/0xa0
[<ffffffffa04f70d2>] process_discard+0x2a2/0x2d0 [dm_thin_pool]
[<ffffffffa04f6a78>] ? remap_and_issue+0x38/0x50 [dm_thin_pool]
[<ffffffffa04f7c3b>] process_deferred_bios+0x7b/0x230 [dm_thin_pool]
[<ffffffffa04f7df0>] ? process_deferred_bios+0x230/0x230 [dm_thin_pool]
[<ffffffffa04f7e42>] do_worker+0x52/0x60 [dm_thin_pool]
[<ffffffff81056fa9>] process_one_work+0x129/0x450
[<ffffffff81059b9c>] worker_thread+0x17c/0x3c0
[<ffffffff81059a20>] ? manage_workers+0x120/0x120
[<ffffffff8105eabe>] kthread+0x9e/0xb0
[<ffffffff814ceda4>] kernel_thread_helper+0x4/0x10
[<ffffffff8105ea20>] ? kthread_freezable_should_stop+0x70/0x70
[<ffffffff814ceda0>] ? gs_change+0x13/0x13
---[ end trace 7e0a523bc5e52692 ]---
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
| -rw-r--r-- | drivers/md/dm-thin.c | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c index 301db0f45d3b..69a2d51ef4e1 100644 --- a/drivers/md/dm-thin.c +++ b/drivers/md/dm-thin.c @@ -1180,6 +1180,7 @@ static void no_space(struct cell *cell) static void process_discard(struct thin_c *tc, struct bio *bio) { int r; + unsigned long flags; struct pool *pool = tc->pool; struct cell *cell, *cell2; struct cell_key key, key2; @@ -1221,7 +1222,9 @@ static void process_discard(struct thin_c *tc, struct bio *bio) m->bio = bio; if (!ds_add_work(&pool->all_io_ds, &m->list)) { + spin_lock_irqsave(&pool->lock, flags); list_add(&m->list, &pool->prepared_discards); + spin_unlock_irqrestore(&pool->lock, flags); wake_worker(pool); } } else { @@ -2629,8 +2632,10 @@ static int thin_endio(struct dm_target *ti, if (h->all_io_entry) { INIT_LIST_HEAD(&work); ds_dec(h->all_io_entry, &work); + spin_lock_irqsave(&pool->lock, flags); list_for_each_entry_safe(m, tmp, &work, list) list_add(&m->list, &pool->prepared_discards); + spin_unlock_irqrestore(&pool->lock, flags); } mempool_free(h, pool->endio_hook_pool); |