On Sat, Dec 18, 2021 at 11:50:20AM -0800, syzbot wrote:
> INFO: task jbd2/sda1-8:2937 blocked for more than 143 seconds.
> Not tainted 5.16.0-rc5-syzkaller #0
> "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
sched_setattr(0x0, &(0x7f0000000080)={0x38, 0x1, 0x0, 0x0, 0x1}, 0x0)
so you've set a SCHED_FIFO priority and then are surprised that some
tasks are getting starved?
> task:jbd2/sda1-8 state:D stack:27112 pid: 2937 ppid: 2 flags:0x00004000
> Call Trace:
> <TASK>
> context_switch kernel/sched/core.c:4972 [inline]
> __schedule+0xa9a/0x4940 kernel/sched/core.c:6253
> schedule+0xd2/0x260 kernel/sched/core.c:6326
> io_schedule+0xee/0x170 kernel/sched/core.c:8371
> bit_wait_io+0x12/0xd0 kernel/sched/wait_bit.c:209
> __wait_on_bit+0x60/0x190 kernel/sched/wait_bit.c:49
> out_of_line_wait_on_bit+0xd5/0x110 kernel/sched/wait_bit.c:64
> wait_on_bit_io include/linux/wait_bit.h:101 [inline]
> __wait_on_buffer+0x7a/0x90 fs/buffer.c:122
> wait_on_buffer include/linux/buffer_head.h:356 [inline]
> journal_wait_on_commit_record fs/jbd2/commit.c:175 [inline]
> jbd2_journal_commit_transaction+0x4e3c/0x6be0 fs/jbd2/commit.c:931
> kjournald2+0x1d0/0x930 fs/jbd2/journal.c:213
> kthread+0x405/0x4f0 kernel/kthread.c:327
> ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
> </TASK>
>
> Showing all locks held in the system:
> 1 lock held by khungtaskd/27:
> #0: ffffffff8bb812e0 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x53/0x260 kernel/locking/lockdep.c:6458
> 1 lock held by udevd/2974:
> 2 locks held by getty/3287:
> #0: ffff88807ec56098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:252
> #1: ffffc90002b8e2e8 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0xcf0/0x1230 drivers/tty/n_tty.c:2113
> 2 locks held by kworker/1:0/3663:
> #0: ffff888010c76538 ((wq_completion)rcu_gp){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
> #0: ffff888010c76538 ((wq_completion)rcu_gp){+.+.}-{0:0}, at: arch_atomic_long_set include/linux/atomic/atomic-long.h:41 [inline]
> #0: ffff888010c76538 ((wq_completion)rcu_gp){+.+.}-{0:0}, at: atomic_long_set include/linux/atomic/atomic-instrumented.h:1198 [inline]
> #0: ffff888010c76538 ((wq_completion)rcu_gp){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:635 [inline]
> #0: ffff888010c76538 ((wq_completion)rcu_gp){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:662 [inline]
> #0: ffff888010c76538 ((wq_completion)rcu_gp){+.+.}-{0:0}, at: process_one_work+0x896/0x1690 kernel/workqueue.c:2269
> #1: ffffc90001b27db0 ((work_completion)(&rew.rew_work)){+.+.}-{0:0}, at: process_one_work+0x8ca/0x1690 kernel/workqueue.c:2273
> 2 locks held by syz-executor.2/13278:
> #0: ffffffff8bc4c6c8 (perf_sched_mutex){+.+.}-{3:3}, at: account_event kernel/events/core.c:11445 [inline]
> #0: ffffffff8bc4c6c8 (perf_sched_mutex){+.+.}-{3:3}, at: perf_event_alloc.part.0+0x31f9/0x3b10 kernel/events/core.c:11678
> #1: ffffffff8bb8a668 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:290 [inline]
> #1: ffffffff8bb8a668 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x4fa/0x620 kernel/rcu/tree_exp.h:836
>
> =============================================
>
> NMI backtrace for cpu 0
> CPU: 0 PID: 27 Comm: khungtaskd Not tainted 5.16.0-rc5-syzkaller #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> Call Trace:
> <TASK>
> __dump_stack lib/dump_stack.c:88 [inline]
> dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
> nmi_cpu_backtrace.cold+0x47/0x144 lib/nmi_backtrace.c:111
> nmi_trigger_cpumask_backtrace+0x1b3/0x230 lib/nmi_backtrace.c:62
> trigger_all_cpu_backtrace include/linux/nmi.h:146 [inline]
> check_hung_uninterruptible_tasks kernel/hung_task.c:210 [inline]
> watchdog+0xc1d/0xf50 kernel/hung_task.c:295
> kthread+0x405/0x4f0 kernel/kthread.c:327
> ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
> </TASK>
> Sending NMI from CPU 0 to CPUs 1:
> NMI backtrace for cpu 1
> CPU: 1 PID: 10 Comm: kworker/u4:1 Not tainted 5.16.0-rc5-syzkaller #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> Workqueue: events_unbound toggle_allocation_gate
> RIP: 0010:__kasan_check_read+0x4/0x10 mm/kasan/shadow.c:31
> Code: 44 07 48 85 db 0f 85 d0 9f 45 07 48 83 c4 60 5b 5d 41 5c 41 5d c3 c3 e9 d0 a0 45 07 cc cc cc cc cc cc cc cc cc cc 48 8b 0c 24 <89> f6 31 d2 e9 f3 f9 ff ff 0f 1f 00 48 8b 0c 24 89 f6 ba 01 00 00
> RSP: 0018:ffffc90000f0f630 EFLAGS: 00000002
> RAX: 0000000000000002 RBX: 1ffff920001e1ece RCX: ffffffff815b774f
> RDX: 0000000000000092 RSI: 0000000000000008 RDI: ffffffff8ff77a10
> RBP: 0000000000000100 R08: 0000000000000000 R09: ffffffff8ff77a17
> R10: 0000000000000001 R11: 000000000000003f R12: 0000000000000008
> R13: ffff888011c7eda8 R14: 0000000000000092 R15: ffff888011c7edc8
> FS: 0000000000000000(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000
> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00005555557b2708 CR3: 000000000b88e000 CR4: 00000000003506e0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> Call Trace:
> <TASK>
> instrument_atomic_read include/linux/instrumented.h:71 [inline]
> test_bit include/asm-generic/bitops/instrumented-non-atomic.h:134 [inline]
> hlock_class kernel/locking/lockdep.c:199 [inline]
> mark_lock+0xef/0x17b0 kernel/locking/lockdep.c:4583
> mark_usage kernel/locking/lockdep.c:4526 [inline]
> __lock_acquire+0x8a7/0x54a0 kernel/locking/lockdep.c:4981
> lock_acquire kernel/locking/lockdep.c:5637 [inline]
> lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5602
> __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
> _raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:154
> spin_lock include/linux/spinlock.h:349 [inline]
> __get_locked_pte+0x2b6/0x4d0 mm/memory.c:1722
> get_locked_pte include/linux/mm.h:2160 [inline]
> __text_poke+0x1ae/0x8c0 arch/x86/kernel/alternative.c:1000
> text_poke_bp_batch+0x3d7/0x560 arch/x86/kernel/alternative.c:1361
> text_poke_flush arch/x86/kernel/alternative.c:1451 [inline]
> text_poke_flush arch/x86/kernel/alternative.c:1448 [inline]
> text_poke_finish+0x16/0x30 arch/x86/kernel/alternative.c:1458
> arch_jump_label_transform_apply+0x13/0x20 arch/x86/kernel/jump_label.c:146
> jump_label_update+0x1d5/0x430 kernel/jump_label.c:830
> static_key_enable_cpuslocked+0x1b1/0x260 kernel/jump_label.c:177
> static_key_enable+0x16/0x20 kernel/jump_label.c:190
> toggle_allocation_gate mm/kfence/core.c:732 [inline]
> toggle_allocation_gate+0x100/0x390 mm/kfence/core.c:724
> process_one_work+0x9b2/0x1690 kernel/workqueue.c:2298
> worker_thread+0x658/0x11f0 kernel/workqueue.c:2445
> kthread+0x405/0x4f0 kernel/kthread.c:327
> ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
> </TASK>
> sd 0:0:1:0: tag#6693 FAILED Result: hostbyte=DID_ABORT driverbyte=DRIVER_OK cmd_age=0s
> sd 0:0:1:0: tag#6693 CDB: opcode=0xe5 (vendor)
> sd 0:0:1:0: tag#6693 CDB[00]: e5 f4 32 73 2f 4e 09 6d 26 e2 c7 35 d1 35 12 1c
> sd 0:0:1:0: tag#6693 CDB[10]: 92 1b da 40 b8 58 5b a8 d4 7d 34 f3 90 4c f1 2d
> sd 0:0:1:0: tag#6693 CDB[20]: ba
> ----------------
> Code disassembly (best guess):
> 0: 44 07 rex.R (bad)
> 2: 48 85 db test %rbx,%rbx
> 5: 0f 85 d0 9f 45 07 jne 0x7459fdb
> b: 48 83 c4 60 add $0x60,%rsp
> f: 5b pop %rbx
> 10: 5d pop %rbp
> 11: 41 5c pop %r12
> 13: 41 5d pop %r13
> 15: c3 retq
> 16: c3 retq
> 17: e9 d0 a0 45 07 jmpq 0x745a0ec
> 1c: cc int3
> 1d: cc int3
> 1e: cc int3
> 1f: cc int3
> 20: cc int3
> 21: cc int3
> 22: cc int3
> 23: cc int3
> 24: cc int3
> 25: cc int3
> 26: 48 8b 0c 24 mov (%rsp),%rcx
> * 2a: 89 f6 mov %esi,%esi <-- trapping instruction
> 2c: 31 d2 xor %edx,%edx
> 2e: e9 f3 f9 ff ff jmpq 0xfffffa26
> 33: 0f 1f 00 nopl (%rax)
> 36: 48 8b 0c 24 mov (%rsp),%rcx
> 3a: 89 f6 mov %esi,%esi
> 3c: ba .byte 0xba
> 3d: 01 00 add %eax,(%rax)
>
>
> ---
> This report is generated by a bot. It may contain errors.
> See https://goo.gl/tpsmEJ for more information about syzbot.
> syzbot engineers can be reached at syzkaller@xxxxxxxxxxxxxxxx.
>
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> syzbot can test patches for this issue, for details see:
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