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: 255d, last: 1d02h
Sample crash report:
rcu: INFO: rcu_preempt detected expedited stalls on CPUs/tasks: { 1-.... } 2643 jiffies s: 25181 root: 0x2/.
rcu: blocking rcu_node structures (internal RCU debug):
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 7228 Comm: syz.0.845 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:check_preemption_disabled+0x18/0x110 lib/smp_processor_id.c:14
Code: cc cc 48 c7 c7 40 68 df 8a 48 c7 c6 80 68 df 8a eb 00 55 41 57 41 56 53 48 83 ec 10 65 48 8b 04 25 28 00 00 00 48 89 44 24 08 <65> 8b 05 71 7c cf 75 65 8b 0d 12 d2 cf 75 f7 c1 ff ff ff 7f 74 1f
RSP: 0018:ffffc900001e0928 EFLAGS: 00000086
RAX: 2ea253ff23992800 RBX: ffff88802f99da00 RCX: ffffffff96c16103
RDX: dffffc0000000000 RSI: ffffffff8a8c2580 RDI: ffffffff8adf68a0
RBP: ffffc900001e0a20 R08: ffff8880b8f357cb R09: 1ffff110171e6af9
R10: dffffc0000000000 R11: ffffed10171e6afa R12: 0000000000000000
R13: 0000000000000000 R14: 7e8285bf9ccb5258 R15: 0000000000000000
FS: 00007fa0b41486c0(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000110c35298c CR3: 00000000784ee000 CR4: 00000000003506e0
DR0: 0000200000000300 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
<IRQ>
lockdep_recursion_inc kernel/locking/lockdep.c:462 [inline]
lockdep_hardirqs_on_prepare+0x1b2/0x7c0 kernel/locking/lockdep.c:4319
trace_hardirqs_on+0x34/0x40 kernel/trace/trace_preemptirq.c:49
asm_sysvec_irq_work+0x16/0x20 arch/x86/include/asm/idtentry.h:728
RIP: 0010:rcu_read_unlock_special+0x7f/0x510 kernel/rcu/tree_plugin.h:685
Code: eb 03 48 b8 f1 f1 f1 f1 f8 f2 f2 f2 4a 89 04 2b 42 c7 44 2b 08 f8 f3 f3 f3 65 44 8b 35 32 7b 95 7e 41 f7 c6 00 00 f0 00 74 40 <48> c7 44 24 40 0e 36 e0 45 4a c7 04 2b 00 00 00 00 42 c7 44 2b 08
RSP: 0018:ffffc900001e0ae0 EFLAGS: 00000206
RAX: 2ea253ff23992800 RBX: 1ffff9200003c164 RCX: 2ea253ff23992800
RDX: dffffc0000000000 RSI: ffffffff8a8c18a0 RDI: ffffffff8adf68a0
RBP: ffffc900001e0bd0 R08: ffff8880b8f357cb R09: 1ffff110171e6af9
R10: dffffc0000000000 R11: ffffed10171e6afa R12: 0000000000000246
R13: dffffc0000000000 R14: ffff8880b8f3bb00 R15: 0000000000000002
__rcu_read_unlock+0x78/0xd0 kernel/rcu/tree_plugin.h:426
rcu_read_unlock include/linux/rcupdate.h:823 [inline]
ieee80211_iterate_active_interfaces_atomic+0x156/0x170 net/mac80211/util.c:826
mac80211_hwsim_beacon+0xb7/0x1b0 drivers/net/wireless/mac80211_hwsim.c:2148
__run_hrtimer kernel/time/hrtimer.c:1751 [inline]
__hrtimer_run_queues+0x522/0xc90 kernel/time/hrtimer.c:1815
hrtimer_run_softirq+0x173/0x290 kernel/time/hrtimer.c:1832
handle_softirqs+0x291/0x910 kernel/softirq.c:596
__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:mod_objcg_state+0x5b7/0x8b0 mm/memcontrol.c:3218
Code: 00 00 00 0f 85 6f 01 00 00 48 8d 65 d8 5b 41 5c 41 5d 41 5e 41 5f 5d c3 e8 56 54 58 08 41 f7 c6 00 02 00 00 74 a5 fb 4d 85 ff <75> a4 eb aa e8 e0 e6 38 02 85 c0 0f 84 9b fb ff ff 48 c7 c0 28 e9
RSP: 0018:ffffc9000458fb00 EFLAGS: 00000246
RAX: 2ea253ff23992800 RBX: 1ffff920008b1f6c RCX: 2ea253ff23992800
RDX: dffffc0000000000 RSI: ffffffff8a8c18a0 RDI: ffffffff8adf68a0
RBP: ffffc9000458fc20 R08: ffff8880b8f357cb R09: 1ffff110171e6af9
R10: dffffc0000000000 R11: ffffed10171e6afa R12: ffff8880b8f36958
R13: dffffc0000000000 R14: 0000000000000a06 R15: 0000000000000000
memcg_slab_free_hook+0x167/0x200 mm/slab.h:570
slab_free mm/slub.c:3682 [inline]
kmem_cache_free+0xe0/0x2a0 mm/slub.c:3709
__dentry_kill+0x4db/0x630 fs/dcache.c:625
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: 0033:0x7fa0b319e159
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:00007fa0b4148028 EFLAGS: 00000246 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 00007fa0b3425fa0 RCX: 00007fa0b319e159
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 000000000000000d
RBP: 00007fa0b323506b R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fa0b3426038 R14: 00007fa0b3425fa0 R15: 00007ffe7024b208
</TASK>
* Struck through repros no longer work on HEAD.