syzbot

 sign-in | mailing list | source | docs
🐞 Open [908]
🐞 Fixed [143]
🐞 Invalid [1090]
⬇ Missing Backports [73]
≡ Crashes
Kernel Health Bugs/Month Bug Lifetimes Fuzzing
💬 Send us feedback

INFO: rcu detected stall in sys_mkdirat (2)

Status: upstream: reported on 2026/05/01 18:50
Reported-by: syzbot+64943c92e9ed0fc050a1@syzkaller.appspotmail.com
First crash: 2d20h, last: 2d20h
▶ ▼ Similar bugs (7)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.1 INFO: rcu detected stall in sys_mkdirat 1 2 528d 567d 0/3 auto-obsoleted due to no activity on 2025/03/02 02:09
linux-5.15 INFO: rcu detected stall in sys_mkdirat 1 1 908d 908d 0/3 auto-obsoleted due to no activity on 2024/02/15 18:20
upstream INFO: rcu detected stall in sys_mkdirat ext4 net 1 3 1118d 1234d 0/29 auto-obsoleted due to no activity on 2023/07/11 04:05
upstream INFO: rcu detected stall in sys_mkdirat (2) mm 1 44 302d 503d 0/29 auto-obsoleted due to no activity on 2025/10/13 21:11
linux-5.15 INFO: rcu detected stall in sys_mkdirat (3) 1 6 1d00h 179d 0/3 upstream: reported on 2025/11/05 18:14
linux-5.15 INFO: rcu detected stall in sys_mkdirat (2) 1 1 430d 430d 0/3 auto-obsoleted due to no activity on 2025/06/08 06:38
android-5-15 BUG: soft lockup in sys_mkdirat 1 8 697d 749d 0/2 auto-obsoleted due to no activity on 2024/09/03 20:00

Sample crash report:
rcu: INFO: rcu_preempt detected expedited stalls on CPUs/tasks: { P16264 1-.... } 2666 jiffies s: 72437 root: 0x2/T
rcu: blocking rcu_node structures (internal RCU debug):
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 16263 Comm: syz.3.3401 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
RIP: 0010:__cant_migrate+0x15a/0x2f0 kernel/sched/core.c:10031
Code: 08 00 00 00 00 65 48 8b 04 25 28 00 00 00 48 3b 84 24 80 00 00 00 0f 85 09 01 00 00 48 8d 65 d8 5b 41 5c 41 5d 41 5e 41 5f 5d <c3> 48 89 7c 24 18 89 74 24 14 48 c7 c0 00 f2 80 8c 48 c1 e8 03 42
RSP: 0018:ffffc900001e0798 EFLAGS: 00000046
RAX: e91e5d0efcb59900 RBX: ffffc9000c94b000 RCX: dffffc0000000000
RDX: 0000000000000100 RSI: 000000000000024e RDI: ffffffff8a9186a0
RBP: ffffc900001e0898 R08: dffffc0000000000 R09: 1ffffffff215f248
R10: dffffc0000000000 R11: fffffbfff215f249 R12: ffffffff8cb7fca0
R13: ffff88801c6b4f98 R14: ffff88801c6b4fa8 R15: 0000000000000001
FS:  00007f5fe59f66c0(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fd8c9407d58 CR3: 0000000026711000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000008d24 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
 <IRQ>
 __bpf_prog_run include/linux/filter.h:590 [inline]
 bpf_prog_run include/linux/filter.h:614 [inline]
 bpf_prog_run_array include/linux/bpf.h:1668 [inline]
 trace_call_bpf+0x2e8/0x6b0 kernel/trace/bpf_trace.c:135
 perf_trace_run_bpf_submit+0x79/0x1c0 kernel/events/core.c:10027
 perf_trace_preemptirq_template+0x268/0x320 include/trace/events/preemptirq.h:14
 trace_irq_enable_rcuidle+0xd3/0x140 include/trace/events/preemptirq.h:40
 trace_hardirqs_on+0x24/0x40 kernel/trace/trace_preemptirq.c:44
 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 d2 33 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:ffffc900001e0ac0 EFLAGS: 00000206
RAX: e91e5d0efcb59900 RBX: 1ffff9200003c160 RCX: e91e5d0efcb59900
RDX: dffffc0000000000 RSI: ffffffff8a8c1120 RDI: ffffffff8adf1320
RBP: ffffc900001e0bb0 R08: ffff8880b8f3580b R09: 1ffff110171e6b01
R10: dffffc0000000000 R11: ffffed10171e6b02 R12: 0000000000000246
R13: dffffc0000000000 R14: ffff8880b8f3b900 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:2147
 __run_hrtimer kernel/time/hrtimer.c:1747 [inline]
 __hrtimer_run_queues+0x54a/0xd50 kernel/time/hrtimer.c:1811
 hrtimer_run_softirq+0x183/0x2a0 kernel/time/hrtimer.c:1828
 handle_softirqs+0x2a1/0x930 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:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [inline]
RIP: 0010:_raw_spin_unlock_irqrestore+0xbc/0x120 kernel/locking/spinlock.c:194
Code: c7 44 24 20 00 00 00 00 9c 8f 44 24 20 f7 44 24 20 00 02 00 00 41 c6 04 07 f8 75 4b f7 c3 00 02 00 00 74 01 fb bf 01 00 00 00 <e8> 2f ed 20 f7 65 8b 05 80 70 ca 75 85 c0 74 3c 48 c7 04 24 0e 36
RSP: 0018:ffffc9000c81fac0 EFLAGS: 00000206
RAX: dffffc0000000004 RBX: 0000000000000a02 RCX: e91e5d0efcb59900
RDX: dffffc0000000000 RSI: ffffffff8a8c1120 RDI: 0000000000000001
RBP: ffffc9000c81fb58 R08: ffff8880b8f3580b R09: 1ffff110171e6b01
R10: dffffc0000000000 R11: ffffed10171e6b02 R12: dffffc0000000000
R13: ffff888063350000 R14: ffffffff96ebd5b8 R15: 1ffff92001903f58
 __debug_check_no_obj_freed lib/debugobjects.c:988 [inline]
 debug_check_no_obj_freed+0x515/0x530 lib/debugobjects.c:1009
 free_pages_prepare mm/page_alloc.c:1492 [inline]
 free_pcp_prepare mm/page_alloc.c:1536 [inline]
 free_unref_page_prepare+0x2a6/0x9a0 mm/page_alloc.c:3413
 free_unref_page+0x2e/0x3f0 mm/page_alloc.c:3508
 free_slab mm/slub.c:2036 [inline]
 discard_slab mm/slub.c:2042 [inline]
 __unfreeze_partials+0x1a5/0x200 mm/slub.c:2591
 put_cpu_partial+0x17c/0x250 mm/slub.c:2667
 qlink_free mm/kasan/quarantine.c:168 [inline]
 qlist_free_all+0x76/0xe0 mm/kasan/quarantine.c:187
 kasan_quarantine_reduce+0x144/0x160 mm/kasan/quarantine.c:294
 __kasan_slab_alloc+0x1e/0x80 mm/kasan/common.c:306
 kasan_slab_alloc include/linux/kasan.h:201 [inline]
 slab_post_alloc_hook+0x4b/0x480 mm/slab.h:737
 slab_alloc_node mm/slub.c:3359 [inline]
 slab_alloc mm/slub.c:3367 [inline]
 __kmem_cache_alloc_lru mm/slub.c:3374 [inline]
 kmem_cache_alloc+0x123/0x2f0 mm/slub.c:3383
 getname_flags+0xb7/0x500 fs/namei.c:139
 getname fs/namei.c:218 [inline]
 __do_sys_mkdirat fs/namei.c:4154 [inline]
 __se_sys_mkdirat fs/namei.c:4152 [inline]
 __x64_sys_mkdirat+0x78/0x90 fs/namei.c:4152
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f5fe779cdd9
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:00007f5fe59f6028 EFLAGS: 00000246 ORIG_RAX: 0000000000000102
RAX: ffffffffffffffda RBX: 00007f5fe7a15fa0 RCX: 00007f5fe779cdd9
RDX: 00000000000001ff RSI: 0000200000000040 RDI: ffffffffffffff9c
RBP: 00007f5fe7832d69 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f5fe7a16038 R14: 00007f5fe7a15fa0 R15: 00007ffc340a6268
 </TASK>

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/05/01 18:50 linux-6.1.y 4931e0e1673d 753c55b9 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-perf INFO: rcu detected stall in sys_mkdirat
* Struck through repros no longer work on HEAD.