block: fix ext_dev_lock lockdep report

commit 4d66e5e9b6d720d8463e11d027bd4ad91c8b1318 upstream.

 =================================
 [ 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: 2da78092dda1 "block:
Fix dev_t minor allocation lifetime".  Both this and 2da78092dda1 are
candidates for -stable.

Fixes: 2da78092dda1 ("block: Fix dev_t minor allocation lifetime")
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>
[lizf: Backported to 3.4: adjust context]
Signed-off-by: Zefan Li <lizefan@huawei.com>

diff --git a/block/genhd.c b/block/genhd.c
index 7a2a8dc9bc5f4b9d514550924dbefd552a22cf42..618ca1aaa858a8850d36f07ac8d7b360f80a478c 100644 (file)
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -420,13 +420,13 @@ int blk_alloc_devt(struct hd_struct *part, dev_t *devt)
        do {
                if (!idr_pre_get(&ext_devt_idr, GFP_KERNEL))
                        return -ENOMEM;
-               spin_lock(&ext_devt_lock);
+               spin_lock_bh(&ext_devt_lock);
                rc = idr_get_new(&ext_devt_idr, part, &idx);
                if (!rc && idx >= NR_EXT_DEVT) {
                        idr_remove(&ext_devt_idr, idx);
                        rc = -EBUSY;
                }
-               spin_unlock(&ext_devt_lock);
+               spin_unlock_bh(&ext_devt_lock);
        } while (rc == -EAGAIN);
 
        if (rc)
@@ -451,9 +451,9 @@ 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);
        }
 }
 
@@ -684,13 +684,13 @@ 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;