]> git.baikalelectronics.ru Git - kernel.git/commit
btrfs: correct zstd workspace manager lock to use spin_lock_bh()
authorDennis Zhou <dennis@kernel.org>
Fri, 17 May 2019 23:16:26 +0000 (19:16 -0400)
committerDavid Sterba <dsterba@suse.com>
Tue, 28 May 2019 16:54:09 +0000 (18:54 +0200)
commitd59e39096001afca3bf24f1785918fa8ea32c938
treeb0c563edfa0d2d14cd37c5db10e5d15959dd57ce
parent26e7b0c8e210d8bb4bd315939e143d9c9d1f27e3
btrfs: correct zstd workspace manager lock to use spin_lock_bh()

The btrfs zstd workspace manager uses a background timer to reclaim not
recently used workspaces. I used spin_lock() from this context which
should have been caught with lockdep, but was not. This deadlock was
reported in bugzilla. The fix is to switch the zstd wsm lock to use
spin_lock_bh() from the softirq context.

This happened quite relibably on ppc64, unlike on other architectures.

  [  313.402874] ================================
  [  313.402875] WARNING: inconsistent lock state
  [  313.402879] 5.1.0-rc7 #1 Not tainted
  [  313.402880] --------------------------------
  [  313.402882] inconsistent {SOFTIRQ-ON-W} -> {IN-SOFTIRQ-W} usage.
  [  313.402885] swapper/5/0 [HC0[0]:SC1[1]:HE1:SE0] takes:
  [  313.402888] 0000000080d1120c (&(&wsm.lock)->rlock){+.?.}, at: .zstd_reclaim_timer_fn+0x40/0x230
  [  313.402895] {SOFTIRQ-ON-W} state was registered at:
  [  313.402899]   .lock_acquire+0xd0/0x240
  [  313.402903]   ._raw_spin_lock+0x34/0x60
  [  313.402906]   .zstd_get_workspace+0xd0/0x360
  [  313.402908]   .end_compressed_bio_read+0x3b8/0x540
  [  313.402911]   .bio_endio+0x174/0x2c0
  [  313.402914]   .end_workqueue_fn+0x4c/0x70
  [  313.402917]   .normal_work_helper+0x138/0x7e0
  [  313.402920]   .process_one_work+0x324/0x790
  [  313.402922]   .worker_thread+0x68/0x570
  [  313.402925]   .kthread+0x19c/0x1b0
  [  313.402928]   .ret_from_kernel_thread+0x58/0x78
  [  313.402930] irq event stamp: 2629216
  [  313.402933] hardirqs last  enabled at (2629216): [<c0000000009da738>] ._raw_spin_unlock_irq+0x38/0x60
  [  313.402936] hardirqs last disabled at (2629215): [<c0000000009da4c4>] ._raw_spin_lock_irq+0x24/0x70
  [  313.402939] softirqs last  enabled at (2629212): [<c0000000000af9fc>] .irq_enter+0x8c/0xd0
  [  313.402942] softirqs last disabled at (2629213): [<c0000000000afb58>] .irq_exit+0x118/0x170
  [  313.402944]
 other info that might help us debug this:
  [  313.402945]  Possible unsafe locking scenario:

  [  313.402947]        CPU0
  [  313.402948]        ----
  [  313.402949]   lock(&(&wsm.lock)->rlock);
  [  313.402951]   <Interrupt>
  [  313.402952]     lock(&(&wsm.lock)->rlock);
  [  313.402954]
  *** DEADLOCK ***

  [  313.402957] 1 lock held by swapper/5/0:
  [  313.402958]  #0: 000000004b612042 ((&wsm.timer)){+.-.}, at: .call_timer_fn+0x0/0x3c0
  [  313.402963]
 stack backtrace:
  [  313.402967] CPU: 5 PID: 0 Comm: swapper/5 Not tainted 5.1.0-rc7 #1
  [  313.402968] Call Trace:
  [  313.402972] [c0000007fa262e70] [c0000000009b3294] .dump_stack+0xe0/0x15c (unreliable)
  [  313.402975] [c0000007fa262f10] [c000000000125548] .print_usage_bug+0x348/0x390
  [  313.402978] [c0000007fa262fd0] [c000000000125cb4] .mark_lock+0x724/0x930
  [  313.402981] [c0000007fa263080] [c000000000126c20] .__lock_acquire+0xc90/0x16a0
  [  313.402984] [c0000007fa2631b0] [c000000000128040] .lock_acquire+0xd0/0x240
  [  313.402987] [c0000007fa263280] [c0000000009da2b4] ._raw_spin_lock+0x34/0x60
  [  313.402990] [c0000007fa263300] [c00000000054b0b0] .zstd_reclaim_timer_fn+0x40/0x230
  [  313.402993] [c0000007fa2633d0] [c000000000158b38] .call_timer_fn+0xc8/0x3c0
  [  313.402996] [c0000007fa2634a0] [c000000000158f74] .expire_timers+0x144/0x260
  [  313.402999] [c0000007fa263550] [c000000000159178] .run_timer_softirq+0xe8/0x230
  [  313.403002] [c0000007fa263680] [c0000000009db288] .__do_softirq+0x188/0x5d4
  [  313.403004] [c0000007fa263790] [c0000000000afb58] .irq_exit+0x118/0x170
  [  313.403008] [c0000007fa263800] [c000000000028d88] .timer_interrupt+0x158/0x430
  [  313.403012] [c0000007fa2638b0] [c0000000000091d4] decrementer_common+0x134/0x140
  [  313.403017] --- interrupt: 901 at replay_interrupt_return+0x0/0x4
     LR = .arch_local_irq_restore.part.0+0x68/0x80
  [  313.403020] [c0000007fa263bb0] [c00000000001a3ac] .arch_local_irq_restore.part.0+0x2c/0x80 (unreliable)
  [  313.403024] [c0000007fa263c30] [c0000000007bbbcc] .cpuidle_enter_state+0xec/0x670
  [  313.403027] [c0000007fa263d00] [c0000000000f5130] .call_cpuidle+0x40/0x90
  [  313.403031] [c0000007fa263d70] [c0000000000f554c] .do_idle+0x2dc/0x3a0
  [  313.403034] [c0000007fa263e30] [c0000000000f59ac] .cpu_startup_entry+0x2c/0x30
  [  313.403037] [c0000007fa263ea0] [c000000000045674] .start_secondary+0x644/0x650
  [  313.403041] [c0000007fa263f90] [c00000000000ad5c] start_secondary_prolog+0x10/0x14

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=203517
Fixes: 5f591757c203 ("btrfs: add zstd compression level support")
CC: stable@vger.kernel.org # 5.1+
Signed-off-by: Dennis Zhou <dennis@kernel.org>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
fs/btrfs/zstd.c