1. Jan 01, 2019
  2. Dec 29, 2018
    • Wenwen Wang's avatar
      gdrom: fix a memory leak bug · 093c4821
      Wenwen Wang authored
      
      
      In probe_gdrom(), the buffer pointed by 'gd.cd_info' is allocated through
      kzalloc() and is used to hold the information of the gdrom device. To
      register and unregister the device, the pointer 'gd.cd_info' is passed to
      the functions register_cdrom() and unregister_cdrom(), respectively.
      However, this buffer is not freed after it is used, which can cause a
      memory leak bug.
      
      This patch simply frees the buffer 'gd.cd_info' in exit_gdrom() to fix the
      above issue.
      
      Signed-off-by: default avatarWenwen Wang <wang6495@umn.edu>
      Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
      093c4821
  3. Dec 23, 2018
  4. Dec 21, 2018
  5. Dec 20, 2018
    • Ming Lei's avatar
      block: save irq state in blkg_lookup_create() · 3a762de5
      Ming Lei authored
      blkg_lookup_create() may be called from pool_map() in which
      irq state is saved, so we have to do that in blkg_lookup_create().
      
      Otherwise, the following lockdep warning can be triggered:
      
      [  104.258537] ================================
      [  104.259129] WARNING: inconsistent lock state
      [  104.259725] 4.20.0-rc6+ #545 Not tainted
      [  104.260268] --------------------------------
      [  104.260865] inconsistent {SOFTIRQ-ON-W} -> {IN-SOFTIRQ-W} usage.
      [  104.261727] swapper/49/0 [HC0[0]:SC1[1]:HE0:SE0] takes:
      [  104.262444] 00000000db365b5d (&(&pool->lock)->rlock#3){+.?.}, at: thin_endio+0xcf/0x2a3 [dm_thin_pool]
      [  104.263747] {SOFTIRQ-ON-W} state was registered at:
      [  104.264417]   _raw_spin_unlock_irq+0x29/0x4c
      [  104.265014]   blkg_lookup_create+0xdc/0xe6
      [  104.265609]   bio_associate_blkg_from_css+0xd3/0x13f
      [  104.266312]   bio_associate_blkg+0x15a/0x1bb
      [  104.266913]   pool_map+0xe8/0x103 [dm_thin_pool]
      [  104.267572]   __map_bio+0x98/0x29c [dm_mod]
      [  104.268162]   __split_and_process_non_flush+0x29e/0x306 [dm_mod]
      [  104.269003]   __split_and_process_bio+0x16a/0x25b [dm_mod]
      [  104.269971]   __dm_make_request.isra.14+0xdc/0x124 [dm_mod]
      [  104.270973]   generic_make_request+0x3f5/0x68b
      [  104.271676]   process_prepared_mapping+0x166/0x1ef [dm_thin_pool]
      [  104.272531]   schedule_zero+0x239/0x273 [dm_thin_pool]
      [  104.273245]   process_cell+0x60c/0x6f1 [dm_thin_pool]
      [  104.273967]   do_worker+0x60c/0xca8 [dm_thin_pool]
      [  104.274635]   process_one_work+0x4eb/0x834
      [  104.275203]   worker_thread+0x318/0x484
      [  104.275740]   kthread+0x1d1/0x1e1
      [  104.276203]   ret_from_fork+0x3a/0x50
      [  104.276714] irq event stamp: 170003
      [  104.277201] hardirqs last  enabled at (170002): [<ffffffff81bcc33e>] _raw_spin_unlock_irqrestore+0x44/0x6b
      [  104.278535] hardirqs last disabled at (170003): [<ffffffff81bcc1ad>] _raw_spin_lock_irqsave+0x20/0x55
      [  104.280273] softirqs last  enabled at (169978): [<ffffffff810d13d4>] irq_enter+0x4c/0x73
      [  104.281617] softirqs last disabled at (169979): [<ffffffff810d1479>] irq_exit+0x7e/0x11d
      [  104.282744]
      [  104.282744] other info that might help us debug this:
      [  104.283640]  Possible unsafe locking scenario:
      [  104.283640]
      [  104.284452]        CPU0
      [  104.284803]        ----
      [  104.285150]   lock(&(&pool->lock)->rlock#3);
      [  104.285762]   <Interrupt>
      [  104.286130]     lock(&(&pool->lock)->rlock#3);
      [  104.286750]
      [  104.286750]  *** DEADLOCK ***
      [  104.286750]
      [  104.287564] no locks held by swapper/49/0.
      [  104.288129]
      [  104.288129] stack backtrace:
      [  104.288738] CPU: 49 PID: 0 Comm: swapper/49 Not tainted 4.20.0-rc6+ #545
      [  104.289700] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.10.2-2.fc27 04/01/2014
      [  104.290858] Call Trace:
      [  104.291204]  <IRQ>
      [  104.291502]  dump_stack+0x9a/0xe6
      [  104.291968]  mark_lock+0x56c/0x7a6
      [  104.292442]  ? check_usage_backwards+0x209/0x209
      [  104.293086]  __lock_acquire+0x400/0x15bf
      [  104.293662]  ? check_chain_key+0x150/0x1aa
      [  104.294236]  lock_acquire+0x1a6/0x1e3
      [  104.294768]  ? thin_endio+0xcf/0x2a3 [dm_thin_pool]
      [  104.295444]  ? _raw_spin_unlock_irqrestore+0x44/0x6b
      [  104.296143]  ? process_prepared_discard_fail+0x36/0x36 [dm_thin_pool]
      [  104.297031]  _raw_spin_lock_irqsave+0x46/0x55
      [  104.297659]  ? thin_endio+0xcf/0x2a3 [dm_thin_pool]
      [  104.298335]  thin_endio+0xcf/0x2a3 [dm_thin_pool]
      [  104.298997]  ? process_prepared_discard_fail+0x36/0x36 [dm_thin_pool]
      [  104.299886]  ? check_flags+0x20a/0x20a
      [  104.300408]  ? lock_acquire+0x1a6/0x1e3
      [  104.300954]  ? process_prepared_discard_fail+0x36/0x36 [dm_thin_pool]
      [  104.301865]  clone_endio+0x1bb/0x22d [dm_mod]
      [  104.302491]  ? disable_write_zeroes+0x20/0x20 [dm_mod]
      [  104.303200]  ? bio_disassociate_blkg+0xc6/0x15f
      [  104.303836]  ? bio_endio+0x2b2/0x2da
      [  104.304349]  clone_endio+0x1f3/0x22d [dm_mod]
      [  104.304978]  ? disable_write_zeroes+0x20/0x20 [dm_mod]
      [  104.305709]  ? bio_disassociate_blkg+0xc6/0x15f
      [  104.306333]  ? bio_endio+0x2b2/0x2da
      [  104.306853]  clone_endio+0x1f3/0x22d [dm_mod]
      [  104.307476]  ? disable_write_zeroes+0x20/0x20 [dm_mod]
      [  104.308185]  ? bio_disassociate_blkg+0xc6/0x15f
      [  104.308817]  ? bio_endio+0x2b2/0x2da
      [  104.309319]  blk_update_request+0x2de/0x4cc
      [  104.309927]  blk_mq_end_request+0x2a/0x183
      [  104.310498]  blk_done_softirq+0x16a/0x1a6
      [  104.311051]  ? blk_softirq_cpu_dead+0xe2/0xe2
      [  104.311653]  ? __lock_is_held+0x2a/0x87
      [  104.312186]  __do_softirq+0x250/0x4e8
      [  104.312705]  irq_exit+0x7e/0x11d
      [  104.313157]  call_function_single_interrupt+0xf/0x20
      [  104.313860]  </IRQ>
      [  104.314163] RIP: 0010:native_safe_halt+0x2/0x3
      [  104.314792] Code: 63 02 df f0 83 44 24 fc 00 48 89 df e8 cc 3f 7a ff 48 8b 03 a8 08 74 0b 65 81 25 9d 31 45 7e ff ff ff 7f 5b 5d 41 5c c3 fb f4 <c3> f4 c3 0f 1f 44 00 00 41 56 41 55 41 54 55 53 e8 a2 0d 5c ff e8
      [  104.317339] RSP: 0018:ffff888106c9fdc0 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff04
      [  104.318390] RAX: 1ffff11020d92100 RBX: 0000000000000000 RCX: ffffffff81159ac7
      [  104.319366] RDX: 1ffffffff05d5e69 RSI: 0000000000000007 RDI: ffff888106c90d1c
      [  104.320339] RBP: 0000000000000000 R08: dffffc0000000000 R09: 0000000000000001
      [  104.321313] R10: ffffed1025d57ba0 R11: ffffed1025d57b9f R12: 1ffff11020d93fbf
      [  104.322328] R13: 0000000000000031 R14: ffff888106c90040 R15: 0000000000000000
      [  104.323307]  ? lockdep_hardirqs_on+0x26b/0x278
      [  104.323927]  default_idle+0xd9/0x1a8
      [  104.324427]  do_idle+0x162/0x2b2
      [  104.324891]  ? arch_cpu_idle_exit+0x28/0x28
      [  104.325467]  ? mark_held_locks+0x28/0x7f
      [  104.326031]  ? _raw_spin_unlock_irqrestore+0x44/0x6b
      [  104.326719]  cpu_startup_entry+0x1d/0x1f
      [  104.327261]  start_secondary+0x2cb/0x308
      [  104.327806]  ? set_cpu_sibling_map+0x8a3/0x8a3
      [  104.328421]  secondary_startup_64+0xa4/0xb0
      
      Fixes: b978962a
      
       ("blkcg: update blkg_lookup_create() to do locking")
      Cc: Mike Snitzer <snitzer@redhat.com>
      Cc: Dennis Zhou <dennis@kernel.org>
      Signed-off-by: default avatarMing Lei <ming.lei@redhat.com>
      Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
      3a762de5
    • Jens Axboe's avatar
      dm: don't reuse bio for flushes · dbe3ece1
      Jens Axboe authored
      DM currently has a statically allocated bio that it uses to issue empty
      flushes. It doesn't submit this bio, it just uses it for maintaining
      state while setting up clones. Multiple users can access this bio at the
      same time. This wasn't previously an issue, even if it was a bit iffy,
      but with the blkg associations it can become one.
      
      We setup the blkg association, then clone bio's and submit, then remove
      the blkg assocation again. But since we can have multiple tasks doing
      this at the same time, against multiple blkg's, then we can either lose
      references to a blkg, or put it twice. The latter causes complaints on
      the percpu ref being <= 0 when released, and can cause use-after-free as
      well. Ming reports that xfstest generic/475 triggers this:
      
      ------------[ cut here ]------------
      percpu ref (blkg_release) <= 0 (0) after switching to atomic
      WARNING: CPU: 13 PID: 0 at lib/percpu-refcount.c:155 percpu_ref_switch_to_atomic_rcu+0x2c9/0x4a0
      
      Switch to just using an on-stack bio for this, and get rid of the
      embedded bio.
      
      Fixes: 5cdf2e3f
      
       ("blkcg: associate blkg when associating a device")
      Reported-by: default avatarMing Lei <ming.lei@redhat.com>
      Tested-by: default avatarMing Lei <ming.lei@redhat.com>
      Reviewed-by: default avatarMike Snitzer <snitzer@redhat.com>
      Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
      dbe3ece1
  6. Dec 19, 2018