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block: fix ext_dev_lock lockdep report 

=================================
 [ INFO: inconsistent lock state ]
 4.1.0-rc7+ #217 Tainted: G           O
 ---------------------------------
 inconsistent {SOFTIRQ-ON-W} -> {IN-SOFTIRQ-W} usage.
 swapper/6/0 [HC0[0]:SC1[1]:HE1:SE0] takes:
  (ext_devt_lock){+.?...}, at: [<ffffffff8143a60c>] blk_free_devt+0x3c/0x70
 {SOFTIRQ-ON-W} state was registered at:
   [<ffffffff810bf6b1>] __lock_acquire+0x461/0x1e70
   [<ffffffff810c1947>] lock_acquire+0xb7/0x290
   [<ffffffff818ac3a8>] _raw_spin_lock+0x38/0x50
   [<ffffffff8143a07d>] blk_alloc_devt+0x6d/0xd0  <-- take the lock in process context
[..]
  [<ffffffff810bf64e>] __lock_acquire+0x3fe/0x1e70
  [<ffffffff810c00ad>] ? __lock_acquire+0xe5d/0x1e70
  [<ffffffff810c1947>] lock_acquire+0xb7/0x290
  [<ffffffff8143a60c>] ? blk_free_devt+0x3c/0x70
  [<ffffffff818ac3a8>] _raw_spin_lock+0x38/0x50
  [<ffffffff8143a60c>] ? blk_free_devt+0x3c/0x70
  [<ffffffff8143a60c>] blk_free_devt+0x3c/0x70    <-- take the lock in softirq
  [<ffffffff8143bfec>] part_release+0x1c/0x50
  [<ffffffff8158edf6>] device_release+0x36/0xb0
  [<ffffffff8145ac2b>] kobject_cleanup+0x7b/0x1a0
  [<ffffffff8145aad0>] kobject_put+0x30/0x70
  [<ffffffff8158f147>] put_device+0x17/0x20
  [<ffffffff8143c29c>] delete_partition_rcu_cb+0x16c/0x180
  [<ffffffff8143c130>] ? read_dev_sector+0xa0/0xa0
  [<ffffffff810e0e0f>] rcu_process_callbacks+0x2ff/0xa90
  [<ffffffff810e0dcf>] ? rcu_process_callbacks+0x2bf/0xa90
  [<ffffffff81067e2e>] __do_softirq+0xde/0x600

Neil sees this in his tests and it also triggers on pmem driver unbind
for the libnvdimm tests.  This fix is on top of an initial fix by Keith
for incorrect usage of mutex_lock() in this path: 2da78092dd "block:
Fix dev_t minor allocation lifetime".  Both this and 2da78092dd are
candidates for -stable.

Fixes: 2da78092dd ("block: Fix dev_t minor allocation lifetime")
Cc: <stable@vger.kernel.org>
Cc: Keith Busch <keith.busch@intel.com>
Reported-by: NeilBrown <neilb@suse.de>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
hifive-unleashed-5.1
Dan Williams 2015-06-10 23:47:14 -04:00 committed by Jens Axboe
parent c3b4afca70
commit 4d66e5e9b6
1 changed files with 6 additions and 6 deletions
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12
block/genhd.c
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@ -422,9 +422,9 @@ int blk_alloc_devt(struct hd_struct *part, dev_t *devt)
/* allocate ext devt */
idr_preload(GFP_KERNEL);
spin_lock(&ext_devt_lock);
spin_lock_bh(&ext_devt_lock);
idx = idr_alloc(&ext_devt_idr, part, 0, NR_EXT_DEVT, GFP_NOWAIT);
spin_unlock(&ext_devt_lock);
spin_unlock_bh(&ext_devt_lock);
idr_preload_end();
if (idx < 0)
@ -449,9 +449,9 @@ void blk_free_devt(dev_t devt)
return;
if (MAJOR(devt) == BLOCK_EXT_MAJOR) {
spin_lock(&ext_devt_lock);
spin_lock_bh(&ext_devt_lock);
idr_remove(&ext_devt_idr, blk_mangle_minor(MINOR(devt)));
spin_unlock(&ext_devt_lock);
spin_unlock_bh(&ext_devt_lock);
}
}
@ -690,13 +690,13 @@ struct gendisk *get_gendisk(dev_t devt, int *partno)
} else {
struct hd_struct *part;
spin_lock(&ext_devt_lock);
spin_lock_bh(&ext_devt_lock);
part = idr_find(&ext_devt_idr, blk_mangle_minor(MINOR(devt)));
if (part && get_disk(part_to_disk(part))) {
*partno = part->partno;
disk = part_to_disk(part);
}
spin_unlock(&ext_devt_lock);
spin_unlock_bh(&ext_devt_lock);
}
return disk;