On Wed, Apr 11, 2018 at 07:20:19AM -0700, Tejun Heo wrote: > Hello, > > On Wed, Apr 11, 2018 at 12:12:56PM +0200, Alexandru Moise wrote: > > > But we already do this through calling blkcg_exit_queue() from > > > __blk_release_queue(). What's missing? > > > > Hi, > > > > It might be the jetlag but I can't see how you end up calling > > blkcg_exit_queue() from __blk_release_queue(). > > > > As I see it the only way to reach blkcg_exit_queue() is from > > blk_cleanup_queue(), which I don't see anywhere in __blk_release_queue(). > > > > I suspect that I'm just fixing a corner case though and > > the general case is what you describe or similar. > > Ah, that changed recently. Can you please check out the current > upstream git master? > > Thanks. > Just did, without my patch I see this crash: [ 0.759999] CPU: 4 PID: 1 Comm: swapper/0 Not tainted 4.16.0-ARCH+ #81 [7/1949] [ 0.759999] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.11.0-20171110_100015-anatol 04/01/204 [ 0.759999] RIP: 0010:pi_init+0x23f/0x2f0 [ 0.759999] RSP: 0000:ffffc90000197d90 EFLAGS: 00010246 [ 0.759999] RAX: 0000000000000000 RBX: 0000000000000020 RCX: 0000000000000038 [ 0.759999] RDX: 0000000000000001 RSI: 0000000000000001 RDI: 0000000000000000 [ 0.759999] RBP: ffffc90000197e18 R08: 00000000ffffffff R09: 00000000ffffffff [ 0.759999] R10: ffffea0000eda600 R11: ffff88003b69f164 R12: ffffffff82e2d740 [ 0.759999] R13: 00000000ffffffff R14: 0000000000000000 R15: 0000000000000000 [ 0.759999] FS: 0000000000000000(0000) GS:ffff88003e500000(0000) knlGS:0000000000000000 [ 0.759999] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 0.759999] CR2: 0000000000000008 CR3: 0000000002209001 CR4: 00000000000606e0 [ 0.759999] Call Trace: [ 0.759999] pf_init+0x1db/0x3be [ 0.759999] ? pcd_init+0x4e8/0x4e8 [ 0.759999] do_one_initcall+0x9e/0x1b0 [ 0.759999] ? do_early_param+0x97/0x97 [ 0.759999] kernel_init_freeable+0x259/0x2fd [ 0.759999] ? rest_init+0xd0/0xd0 [ 0.759999] ? syscall_slow_exit_work+0x1c/0x160 [ 0.759999] kernel_init+0xe/0x100 [ 0.759999] ret_from_fork+0x3a/0x50 [ 0.759999] Code: 75 6a 49 8b 06 48 8b 40 78 48 85 c0 74 08 4c 89 f7 e8 46 76 51 00 83 c3 01 3b 5d a8 7d 0d 49 [ 0.759999] RIP: pi_init+0x23f/0x2f0 RSP: ffffc90000197d90 [ 0.759999] CR2: 0000000000000008 [ 0.759999] ---[ end trace 12004f267bb8bf7d ]--- [ 0.766666] BUG: unable to handle kernel NULL pointer dereference at 00000000000001b4 [ 0.763350] Kernel panic - not syncing: Attempted to kill init! exitcode=0x00000009 [ 0.763350] [ 0.766666] PGD 0 P4D 0 [ 0.766666] Oops: 0000 [#2] PREEMPT SMP [ 0.766666] CPU: 0 PID: 6 Comm: kworker/u12:0 Tainted: G D 4.16.0-ARCH+ #81 [ 0.766666] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.11.0-20171110_100015-anatol 04/01/20$ [ 0.766666] Workqueue: nvme-reset-wq nvme_reset_work [ 0.766666] RIP: 0010:blk_queue_flag_set+0xf/0x40 [ 0.766666] RSP: 0000:ffffc900001bfcb0 EFLAGS: 00010246 [ 0.766666] RAX: ffff88003b698000 RBX: 0000000000000000 RCX: 0000000000000000 [ 0.766666] RDX: ffff88003b698000 RSI: fffffffffffffff4 RDI: 000000000000001c [ 0.766666] RBP: ffffc900001bfcc0 R08: 0000000000000000 R09: 0000000000000000 [ 0.766666] R10: ffffea0000eaa980 R11: ffffffff814e0970 R12: 000000000000001c [ 0.766666] R13: 0000000000000000 R14: 0000000000000000 R15: ffff88003aad8010 [ 0.766666] FS: 0000000000000000(0000) GS:ffff88003e400000(0000) knlGS:0000000000000000 [ 0.766666] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 0.766666] CR2: 00000000000001b4 CR3: 0000000002209001 CR4: 00000000000606f0 [ 0.766666] Call Trace: [ 0.766666] blk_mq_quiesce_queue+0x23/0x80 [ 0.766666] nvme_dev_disable+0x34f/0x480 [ 0.766666] ? nvme_irq+0x50/0x50 [ 0.766666] ? dev_warn+0x64/0x80 [ 0.766666] nvme_reset_work+0x13de/0x1570 [ 0.766666] ? __switch_to_asm+0x34/0x70 [ 0.766666] ? __switch_to_asm+0x40/0x70 [ 0.766666] ? _raw_spin_unlock_irq+0x15/0x30 [ 0.766666] ? finish_task_switch+0x156/0x210 [ 0.766666] process_one_work+0x20c/0x3d0 [ 0.766666] worker_thread+0x216/0x400 [ 0.766666] kthread+0x125/0x130 [ 0.766666] ? process_one_work+0x3d0/0x3d0 [ 0.766666] ? __kthread_bind_mask+0x60/0x60 [ 0.766666] ret_from_fork+0x3a/0x50 With the patch the crash goes away, Thanks, ../Alex > -- > tejun
