syzbot
INFO: rcu detected stall in dentry_kill
Status:
upstream: reported on 2026/01/20 19:30
Reported-by: syzbot+ecc91afd56cfea8535b2@syzkaller.appspotmail.com
First crash: 239d, last: 1d08h
Sample crash report:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 1-....: (0 ticks this GP) idle=5064/1/0x4000000000000000 softirq=48681/48681 fqs=2100
rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P14367
(detected by 0, t=10506 jiffies, g=57469, q=601 ncpus=2)
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 14367 Comm: syz.4.2657 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:irqentry_exit+0x63/0x70 kernel/entry/common.c:445
Code: 0f 85 51 09 00 00 c3 40 f6 c6 01 74 18 e8 15 09 56 f7 e8 e0 32 31 f7 e8 3b 09 00 00 48 8b 3c 24 e9 52 f7 ff ff e8 fd 5e 3c f7 <e9> 88 0a 56 f7 0f 0b eb b3 0f 1f 40 00 41 56 53 65 8b 1d 26 e5 cf
RSP: 0018:ffffc900001e0d70 EFLAGS: 00000006
RAX: 0000000000000100 RBX: 0000000000000000 RCX: 0cb5c48961d27000
RDX: 1ffffffff1f44808 RSI: 0000000000000000 RDI: ffffc900001e0d78
RBP: 0000000000000000 R08: ffffffff8fa24048 R09: ffffffff8fa24058
R10: ffffffff8fa24050 R11: ffffffff8fa24043 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
FS: 00007fc44c2f76c0(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 0000000027748000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000200000000300 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
<IRQ>
asm_sysvec_irq_work+0x16/0x20 arch/x86/include/asm/idtentry.h:728
RIP: 0010:variable_ffs arch/x86/include/asm/bitops.h:319 [inline]
RIP: 0010:handle_softirqs+0x1b7/0x910 kernel/softirq.c:584
Code: 89 7c 24 2c 0f b7 db 48 c7 c7 80 0e 8b 8a e8 30 5d e3 08 65 66 c7 05 46 61 b4 7e 00 00 e8 c1 5a 39 00 fb 49 c7 c5 c0 a0 80 8c <89> 5c 24 34 b8 ff ff ff ff 0f bc 44 24 34 41 89 c6 41 ff c6 0f 84
RSP: 0018:ffffc900001e0e20 EFLAGS: 00000282
RAX: 0cb5c48961d27000 RBX: 0000000000000200 RCX: 0cb5c48961d27000
RDX: dffffc0000000000 RSI: ffffffff8a8c18a0 RDI: ffffffff8adf68a0
RBP: ffffc900001e0f30 R08: ffff8880b8f357cb R09: 1ffff110171e6af9
R10: dffffc0000000000 R11: ffffed10171e6afa R12: dffffc0000000000
R13: ffffffff8c80a0c0 R14: ffff888027048000 R15: 000000000000000a
__do_softirq kernel/softirq.c:630 [inline]
invoke_softirq kernel/softirq.c:470 [inline]
__irq_exit_rcu+0x13b/0x230 kernel/softirq.c:679
irq_exit_rcu+0x5/0x20 kernel/softirq.c:691
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1118 [inline]
sysvec_apic_timer_interrupt+0xa0/0xc0 arch/x86/kernel/apic/apic.c:1118
</IRQ>
<TASK>
asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691
RIP: 0010:rcu_read_unlock_special+0x1/0x510 kernel/rcu/tree_plugin.h:630
Code: 84 66 00 eb b0 44 89 f1 80 e1 07 80 c1 03 38 c1 7c 94 49 89 fd 4c 89 f7 e8 fc 83 66 00 4c 89 ef eb 84 0f 1f 80 00 00 00 00 55 <48> 89 e5 41 57 41 56 41 55 41 54 53 48 83 e4 e0 48 81 ec c0 00 00
RSP: 0018:ffffc9000c8ef610 EFLAGS: 00000202
RAX: 0000000000000000 RBX: ffff88802704843c RCX: 0000000000080000
RDX: ffffc9000cfe9000 RSI: 0000000000000d58 RDI: ffff888027048000
RBP: 0000000000000000 R08: dffffc0000000000 R09: 1ffffffff2161e48
R10: dffffc0000000000 R11: fffffbfff2161e49 R12: 1ffff11004e09087
R13: dffffc0000000000 R14: ffff888027048440 R15: dffffc0000000000
__rcu_read_unlock+0x78/0xd0 kernel/rcu/tree_plugin.h:426
rcu_read_unlock include/linux/rcupdate.h:823 [inline]
is_bpf_text_address+0x27a/0x2a0 kernel/bpf/core.c:738
kernel_text_address+0x9c/0xd0 kernel/extable.c:125
__kernel_text_address+0x9/0x30 kernel/extable.c:79
unwind_get_return_address+0x49/0x80 arch/x86/kernel/unwind_orc.c:323
arch_stack_walk+0xf2/0x140 arch/x86/kernel/stacktrace.c:26
stack_trace_save+0xa6/0xf0 kernel/stacktrace.c:122
kasan_save_stack+0x3a/0x60 mm/kasan/common.c:46
__kasan_record_aux_stack+0xb2/0xc0 mm/kasan/generic.c:486
call_rcu+0x14f/0x950 kernel/rcu/tree.c:2849
destroy_inode fs/inode.c:316 [inline]
evict+0x810/0x8b0 fs/inode.c:720
__dentry_kill+0x412/0x630 fs/dcache.c:611
dentry_kill+0xb8/0x290 fs/dcache.c:-1
dput+0xfa/0x1d0 fs/dcache.c:918
__fput+0x597/0x8b0 fs/file_table.c:328
task_work_run+0x1d0/0x260 kernel/task_work.c:203
resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
exit_to_user_mode_loop+0xe6/0x110 kernel/entry/common.c:180
exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:213
__syscall_exit_to_user_mode_work kernel/entry/common.c:295 [inline]
syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:306
do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:82
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fc44b39e159
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fc44c2f7028 EFLAGS: 00000246 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 00007fc44b625fa0 RCX: 00007fc44b39e159
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000003
RBP: 00007fc44b43506b R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fc44b626038 R14: 00007fc44b625fa0 R15: 00007ffddcfc0ba8
</TASK>
task:syz.4.2657 state:R running task stack:24464 pid:14367 ppid:4284 flags:0x00004008
Call Trace:
<TASK>
</TASK>
* Struck through repros no longer work on HEAD.