Hello,

syzbot found the following issue on:

HEAD commit: fb0155a0 Merge tag 'nfs-for-5.9-3' of git://git.linux-nfs... git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=10b007cf900000 kernel config: https://syzkaller.appspot.com/x/.config?x=41b736b7ce1b3ea4 dashboard link: https://syzkaller.appspot.com/bug?extid=d2b6e8cc299748fecf25 compiler: gcc (GCC) 10.1.0-syz 20200507 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1249c717900000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1048d9e3900000

The issue was bisected to:

commit c9d8f5f0692d5960ed50970ffe63756fb8f96cdb Author: Kirill Tkhai ktkhai@virtuozzo.com Date: Fri Nov 9 10:33:27 2018 +0000

fuse: Protect fi->nlookup with fi->lock

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=11af769d900000 final oops: https://syzkaller.appspot.com/x/report.txt?x=13af769d900000 console output: https://syzkaller.appspot.com/x/log.txt?x=15af769d900000

IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+d2b6e8cc299748fecf25@syzkaller.appspotmail.com Fixes: c9d8f5f0692d ("fuse: Protect fi->nlookup with fi->lock")

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): ------------[ cut here ]------------ WARNING: CPU: 0 PID: 3922 at kernel/sched/core.c:3013 rq_unlock kernel/sched/sched.h:1326 [inline] WARNING: CPU: 0 PID: 3922 at kernel/sched/core.c:3013 try_invoke_on_locked_down_task+0x21d/0x2f0 kernel/sched/core.c:3019 Kernel panic - not syncing: panic_on_warn set ... CPU: 0 PID: 3922 Comm: systemd-udevd Not tainted 5.9.0-rc7-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: <IRQ> __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x198/0x1fd lib/dump_stack.c:118 panic+0x382/0x7fb kernel/panic.c:231 __warn.cold+0x20/0x4b kernel/panic.c:600 report_bug+0x1bd/0x210 lib/bug.c:198 handle_bug+0x38/0x90 arch/x86/kernel/traps.c:234 exc_invalid_op+0x14/0x40 arch/x86/kernel/traps.c:254 asm_exc_invalid_op+0x12/0x20 arch/x86/include/asm/idtentry.h:536 RIP: 0010:try_invoke_on_locked_down_task+0x21d/0x2f0 kernel/sched/core.c:3013 Code: 45 31 f6 49 39 c0 74 3a 8b 74 24 38 49 8d 78 18 4c 89 04 24 e8 a4 e7 08 00 4c 8b 04 24 4c 89 c7 e8 28 ab d6 06 e9 20 ff ff ff <0f> 0b e9 7d fe ff ff 4c 89 ee 48 89 ef 41 ff d4 41 89 c6 e9 08 ff RSP: 0018:ffffc90000007be0 EFLAGS: 00010046 RAX: 0000000000000000 RBX: 1ffff92000000f7e RCX: 0000000000000001 RDX: 0000000000000000 RSI: ffffffff8162da10 RDI: ffff8880a61a2440 RBP: ffff8880a61a2440 R08: 0000000000000033 R09: ffffffff8a05ae03 R10: 000000000000062e R11: 0000000000000001 R12: ffffffff8162da10 R13: ffffc90000007d08 R14: ffff8880a61a2440 R15: 0000000000000000 rcu_print_task_stall kernel/rcu/tree_stall.h:267 [inline] print_other_cpu_stall kernel/rcu/tree_stall.h:475 [inline] check_cpu_stall kernel/rcu/tree_stall.h:634 [inline] rcu_pending kernel/rcu/tree.c:3639 [inline] rcu_sched_clock_irq.cold+0x97e/0xdfd kernel/rcu/tree.c:2521 update_process_times+0x25/0xa0 kernel/time/timer.c:1710 tick_sched_handle+0x9b/0x180 kernel/time/tick-sched.c:176 tick_sched_timer+0x1d1/0x2a0 kernel/time/tick-sched.c:1328 __run_hrtimer kernel/time/hrtimer.c:1524 [inline] __hrtimer_run_queues+0x1d5/0xfc0 kernel/time/hrtimer.c:1588 hrtimer_interrupt+0x334/0x940 kernel/time/hrtimer.c:1650 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1080 [inline] __sysvec_apic_timer_interrupt+0x147/0x5f0 arch/x86/kernel/apic/apic.c:1097 asm_call_irq_on_stack+0xf/0x20 </IRQ> __run_sysvec_on_irqstack arch/x86/include/asm/irq_stack.h:37 [inline] run_sysvec_on_irqstack_cond arch/x86/include/asm/irq_stack.h:89 [inline] sysvec_apic_timer_interrupt+0xb2/0xf0 arch/x86/kernel/apic/apic.c:1091 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:581 RIP: 0010:preempt_count arch/x86/include/asm/preempt.h:26 [inline] RIP: 0010:check_kcov_mode kernel/kcov.c:163 [inline] RIP: 0010:__sanitizer_cov_trace_pc+0x9/0x60 kernel/kcov.c:197 Code: 5d be 03 00 00 00 e9 76 af 49 02 66 0f 1f 44 00 00 48 8b be b0 01 00 00 e8 b4 ff ff ff 31 c0 c3 90 65 48 8b 14 25 c0 fe 01 00 <65> 8b 05 e0 bf 8b 7e a9 00 01 ff 00 48 8b 34 24 74 0f f6 c4 01 74 RSP: 0018:ffffc90000f075a8 EFLAGS: 00000246 RAX: 0000000000000000 RBX: 0000000000000004 RCX: ffffffff838a0be7 RDX: ffff88809c62c4c0 RSI: ffff88809c62c4c0 RDI: 0000000000000005 RBP: ffff8880a601de80 R08: 0000000000000001 R09: ffffffff8d5f79c7 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000001 R13: 0000000000000183 R14: dffffc0000000000 R15: 0000000000000000 tomoyo_domain_quota_is_ok+0x31a/0x550 security/tomoyo/util.c:1070 tomoyo_supervisor+0x2f2/0xef0 security/tomoyo/common.c:2089 tomoyo_audit_path_log security/tomoyo/file.c:168 [inline] tomoyo_path_permission security/tomoyo/file.c:587 [inline] tomoyo_path_permission+0x270/0x3a0 security/tomoyo/file.c:573 tomoyo_check_open_permission+0x33e/0x380 security/tomoyo/file.c:777 tomoyo_file_open security/tomoyo/tomoyo.c:313 [inline] tomoyo_file_open+0xa3/0xd0 security/tomoyo/tomoyo.c:308 security_file_open+0x52/0x4f0 security/security.c:1574 do_dentry_open+0x358/0x11b0 fs/open.c:804 do_open fs/namei.c:3251 [inline] path_openat+0x1b9a/0x2730 fs/namei.c:3368 do_filp_open+0x17e/0x3c0 fs/namei.c:3395 do_sys_openat2+0x16d/0x420 fs/open.c:1168 do_sys_open fs/open.c:1184 [inline] __do_sys_open fs/open.c:1192 [inline] __se_sys_open fs/open.c:1188 [inline] __x64_sys_open+0x119/0x1c0 fs/open.c:1188 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x7fb405960840 Code: 73 01 c3 48 8b 0d 68 77 20 00 f7 d8 64 89 01 48 83 c8 ff c3 66 0f 1f 44 00 00 83 3d 89 bb 20 00 00 75 10 b8 02 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 31 c3 48 83 ec 08 e8 1e f6 ff ff 48 89 04 24 RSP: 002b:00007fff26dc0bd8 EFLAGS: 00000246 ORIG_RAX: 0000000000000002 RAX: ffffffffffffffda RBX: 00007fff26dc0c70 RCX: 00007fb405960840 RDX: 0000560daddc7fe3 RSI: 00000000000a0800 RDI: 0000560daede0670 RBP: 00007fff26dc1100 R08: 0000560daddc7670 R09: 0000000000000010 R10: 0000000000000000 R11: 0000000000000246 R12: 00007fff26dc0d80 R13: 0000560daed2da60 R14: 0000560daedeeef0 R15: 00007fff26dc0c50 Kernel Offset: disabled Rebooting in 86400 seconds..

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