Hello, syzbot found the following issue on: HEAD commit: b9b4c79e5830 Merge tag 'sound-5.18-rc3' of git://git.kerne.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=118c96ccf00000 kernel config: https://syzkaller.appspot.com/x/.config?x=eb177500e563582f dashboard link: https://syzkaller.appspot.com/bug?extid=b9e4c31d0a1efb34cb03 compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=16ab7a70f00000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=16e54770f00000 The issue was bisected to: commit 0a9a25ca78437b39e691bcc3dc8240455b803d8d Author: Ming Lei <ming.lei@xxxxxxxxxx> Date: Fri Mar 18 13:01:43 2022 +0000 block: let blkcg_gq grab request queue's refcnt bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=128129e0f00000 final oops: https://syzkaller.appspot.com/x/report.txt?x=118129e0f00000 console output: https://syzkaller.appspot.com/x/log.txt?x=168129e0f00000 IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+b9e4c31d0a1efb34cb03@xxxxxxxxxxxxxxxxxxxxxxxxx Fixes: 0a9a25ca7843 ("block: let blkcg_gq grab request queue's refcnt") RBP: 00007ffcdacd3400 R08: 0000000000000002 R09: 0000000000000001 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000004 R13: 431bde82d7b634db R14: 0000000000000000 R15: 0000000000000000 </TASK> ====================================================== WARNING: possible circular locking dependency detected 5.18.0-rc2-syzkaller-00122-gb9b4c79e5830 #0 Not tainted ------------------------------------------------------ syz-executor173/3613 is trying to acquire lock: ffff8880168900a8 ((&sq->pending_timer)){+.-.}-{0:0}, at: del_timer_sync+0x33/0x1b0 kernel/time/timer.c:1363 but task is already holding lock: ffffffff9070b710 (&blkcg->lock){....}-{2:2}, at: spin_lock include/linux/spinlock.h:349 [inline] ffffffff9070b710 (&blkcg->lock){....}-{2:2}, at: blkcg_deactivate_policy block/blk-cgroup.c:1441 [inline] ffffffff9070b710 (&blkcg->lock){....}-{2:2}, at: blkcg_deactivate_policy+0x1e7/0x4e0 block/blk-cgroup.c:1423 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (&blkcg->lock){....}-{2:2}: __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] blkg_create+0x47b/0x1030 block/blk-cgroup.c:301 blkcg_init_queue+0xfe/0x810 block/blk-cgroup.c:1206 __alloc_disk_node+0x260/0x610 block/genhd.c:1381 __blk_alloc_disk+0x35/0x70 block/genhd.c:1421 brd_alloc.part.0+0x27f/0x7a0 drivers/block/brd.c:391 brd_alloc drivers/block/brd.c:374 [inline] brd_init+0x1b8/0x24b drivers/block/brd.c:477 do_one_initcall+0x103/0x650 init/main.c:1298 do_initcall_level init/main.c:1371 [inline] do_initcalls init/main.c:1387 [inline] do_basic_setup init/main.c:1406 [inline] kernel_init_freeable+0x6b1/0x73a init/main.c:1613 kernel_init+0x1a/0x1d0 init/main.c:1502 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298 -> #1 (&q->queue_lock){..-.}-{2:2}: __raw_spin_lock_irq include/linux/spinlock_api_smp.h:119 [inline] _raw_spin_lock_irq+0x32/0x50 kernel/locking/spinlock.c:170 spin_lock_irq include/linux/spinlock.h:374 [inline] throtl_pending_timer_fn+0xf7/0x1690 block/blk-throttle.c:1152 call_timer_fn+0x1a5/0x6b0 kernel/time/timer.c:1421 expire_timers kernel/time/timer.c:1466 [inline] __run_timers.part.0+0x67c/0xa30 kernel/time/timer.c:1734 __run_timers kernel/time/timer.c:1715 [inline] run_timer_softirq+0xb3/0x1d0 kernel/time/timer.c:1747 __do_softirq+0x29b/0x9c2 kernel/softirq.c:558 invoke_softirq kernel/softirq.c:432 [inline] __irq_exit_rcu+0x123/0x180 kernel/softirq.c:637 irq_exit_rcu+0x5/0x20 kernel/softirq.c:649 sysvec_apic_timer_interrupt+0x93/0xc0 arch/x86/kernel/apic/apic.c:1097 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:645 native_safe_halt arch/x86/include/asm/irqflags.h:51 [inline] arch_safe_halt arch/x86/include/asm/irqflags.h:89 [inline] acpi_safe_halt drivers/acpi/processor_idle.c:115 [inline] acpi_idle_do_entry+0x1c6/0x250 drivers/acpi/processor_idle.c:556 acpi_idle_enter+0x361/0x500 drivers/acpi/processor_idle.c:691 cpuidle_enter_state+0x1b1/0xc80 drivers/cpuidle/cpuidle.c:237 cpuidle_enter+0x4a/0xa0 drivers/cpuidle/cpuidle.c:351 call_cpuidle kernel/sched/idle.c:155 [inline] cpuidle_idle_call kernel/sched/idle.c:236 [inline] do_idle+0x3e8/0x590 kernel/sched/idle.c:303 cpu_startup_entry+0x14/0x20 kernel/sched/idle.c:400 start_secondary+0x265/0x340 arch/x86/kernel/smpboot.c:266 secondary_startup_64_no_verify+0xc3/0xcb -> #0 ((&sq->pending_timer)){+.-.}-{0:0}: check_prev_add kernel/locking/lockdep.c:3065 [inline] check_prevs_add kernel/locking/lockdep.c:3188 [inline] validate_chain kernel/locking/lockdep.c:3803 [inline] __lock_acquire+0x2ac6/0x56c0 kernel/locking/lockdep.c:5029 lock_acquire kernel/locking/lockdep.c:5641 [inline] lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5606 del_timer_sync+0x5b/0x1b0 kernel/time/timer.c:1364 throtl_pd_free+0x15/0x40 block/blk-throttle.c:500 blkcg_deactivate_policy block/blk-cgroup.c:1445 [inline] blkcg_deactivate_policy+0x2d2/0x4e0 block/blk-cgroup.c:1423 blk_throtl_exit+0x8a/0x1a0 block/blk-throttle.c:2335 blkcg_init_queue+0x225/0x810 block/blk-cgroup.c:1226 __alloc_disk_node+0x260/0x610 block/genhd.c:1381 __blk_mq_alloc_disk+0x133/0x1c0 block/blk-mq.c:3930 loop_add+0x33d/0x910 drivers/block/loop.c:2012 loop_control_ioctl+0x130/0x4d0 drivers/block/loop.c:2186 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:870 [inline] __se_sys_ioctl fs/ioctl.c:856 [inline] __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:856 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae other info that might help us debug this: Chain exists of: (&sq->pending_timer) --> &q->queue_lock --> &blkcg->lock Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&blkcg->lock); lock(&q->queue_lock); lock(&blkcg->lock); lock((&sq->pending_timer)); *** DEADLOCK *** 2 locks held by syz-executor173/3613: #0: ffff88801dd168e0 (&q->queue_lock){..-.}-{2:2}, at: spin_lock_irq include/linux/spinlock.h:374 [inline] #0: ffff88801dd168e0 (&q->queue_lock){..-.}-{2:2}, at: blkcg_deactivate_policy block/blk-cgroup.c:1434 [inline] #0: ffff88801dd168e0 (&q->queue_lock){..-.}-{2:2}, at: blkcg_deactivate_policy+0xfe/0x4e0 block/blk-cgroup.c:1423 #1: ffffffff9070b710 (&blkcg->lock){....}-{2:2}, at: spin_lock include/linux/spinlock.h:349 [inline] #1: ffffffff9070b710 (&blkcg->lock){....}-{2:2}, at: blkcg_deactivate_policy block/blk-cgroup.c:1441 [inline] #1: ffffffff9070b710 (&blkcg->lock){....}-{2:2}, at: blkcg_deactivate_policy+0x1e7/0x4e0 block/blk-cgroup.c:1423 stack backtrace: CPU: 1 PID: 3613 Comm: syz-executor173 Not tainted 5.18.0-rc2-syzkaller-00122-gb9b4c79e5830 #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 check_noncircular+0x25f/0x2e0 kernel/locking/lockdep.c:2145 check_prev_add kernel/locking/lockdep.c:3065 [inline] check_prevs_add kernel/locking/lockdep.c:3188 [inline] validate_chain kernel/locking/lockdep.c:3803 [inline] __lock_acquire+0x2ac6/0x56c0 kernel/locking/lockdep.c:5029 lock_acquire kernel/locking/lockdep.c:5641 [inline] lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5606 del_timer_sync+0x5b/0x1b0 kernel/time/timer.c:1364 throtl_pd_free+0x15/0x40 block/blk-throttle.c:500 blkcg_deactivate_policy block/blk-cgroup.c:1445 [inline] blkcg_deactivate_policy+0x2d2/0x4e0 block/blk-cgroup.c:1423 blk_throtl_exit+0x8a/0x1a0 block/blk-throttle.c:2335 blkcg_init_queue+0x225/0x810 block/blk-cgroup.c:1226 __alloc_disk_node+0x260/0x610 block/genhd.c:1381 __blk_mq_alloc_disk+0x133/0x1c0 block/blk-mq.c:3930 loop_add+0x33d/0x910 drivers/block/loop.c:2012 loop_control_ioctl+0x130/0x4d0 drivers/block/loop.c:2186 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:870 [inline] __se_sys_ioctl fs/ioctl.c:856 [inline] __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:856 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x7fde66153079 Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 b1 14 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 c0 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007ffcdacd33e8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 0000000000000002 RCX: 00007fde66153079 RDX: 0000000000000000 RSI: 0000000000004c80 RDI: 0000000000000003 RBP: 00007ffcdacd3400 R08: 0000000000000002 R09: 0000000000000001 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000004 R13: 431bde82d7b634db R14: 0000000000000000 R15: 0000000000000000 </TASK> --- 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. syzbot will keep track of this issue. See: https://goo.gl/tpsmEJ#status for how to communicate with syzbot. For information about bisection process see: https://goo.gl/tpsmEJ#bisection syzbot can test patches for this issue, for details see: https://goo.gl/tpsmEJ#testing-patches
