syzbot


INFO: rcu detected stall in sys_openat

Status: upstream: reported C repro on 2025/07/10 07:34
Reported-by: syzbot+6d93f26ac7a5c42350ec@syzkaller.appspotmail.com
First crash: 41d, last: 2d06h
Similar bugs (8)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.1 INFO: rcu detected stall in sys_openat 1 3 712d 745d 0/3 auto-obsoleted due to no activity on 2023/12/16 21:24
upstream INFO: rcu detected stall in sys_openat exfat 1 5 2410d 2488d 0/29 closed as dup on 2018/10/27 13:02
linux-5.15 INFO: rcu detected stall in sys_openat missing-backport origin:upstream 1 C done 35 57d 792d 0/3 upstream: reported C repro on 2023/06/19 20:52
linux-6.1 INFO: rcu detected stall in sys_openat (2) origin:upstream 1 C error 16 5d17h 524d 0/3 upstream: reported C repro on 2024/03/13 11:37
upstream INFO: rcu detected stall in sys_openat (3) mm 1 C error 439 2h33m 716d 0/29 upstream: reported C repro on 2023/09/03 11:10
upstream INFO: rcu detected stall in sys_openat (2) kernfs 1 8 1293d 1505d 0/29 closed as invalid on 2022/02/08 09:50
android-5-15 BUG: soft lockup in sys_openat (2) origin:lts 1 C error 5 343d 393d 0/2 auto-obsoleted due to no activity on 2024/12/19 09:52
android-5-15 BUG: soft lockup in sys_openat 1 21 444d 499d 0/2 auto-obsoleted due to no activity on 2024/07/21 23:03

Sample crash report:
rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 	0-....: (10500 ticks this GP) idle=111c/1/0x4000000000000000 softirq=13981/506536 fqs=5230
rcu: 	         hardirqs   softirqs   csw/system
rcu: 	 number:  2515265     250681            0
rcu: 	cputime:     1649      50349          481   ==> 52490(ms)
rcu: 	(t=10501 jiffies g=11709 q=2561 ncpus=2)
CPU: 0 PID: 5863 Comm: udevd Not tainted 6.6.102-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
RIP: 0010:rcu_read_unlock_special+0x88/0x4c0 kernel/rcu/tree_plugin.h:682
Code: f1 f1 f1 00 f2 f2 f2 4a 89 04 2b 66 42 c7 44 2b 09 f3 f3 42 c6 44 2b 0b f3 65 44 8b 35 39 58 93 7e 41 f7 c6 00 00 f0 00 74 45 <48> c7 44 24 40 0e 36 e0 45 4a c7 04 2b 00 00 00 00 66 42 c7 44 2b
RSP: 0018:ffffc900000078e0 EFLAGS: 00000206
RAX: 5090edb31f450200 RBX: 1ffff92000000f24 RCX: 5090edb31f450200
RDX: dffffc0000000000 RSI: ffffffff8aaab9c0 RDI: ffffffff8afc66c0
RBP: ffffc900000079e0 R08: ffffffff8e4a882f R09: 1ffffffff1c95105
R10: dffffc0000000000 R11: fffffbfff1c95106 R12: ffffffff8cd35400
R13: dffffc0000000000 R14: 0000000000000246 R15: 0000000000000001
FS:  00007ff64a35a880(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f25578e56c0 CR3: 00000000795c5000 CR4: 00000000003506f0
Call Trace:
 <IRQ>
 __rcu_read_unlock+0x7c/0xd0 kernel/rcu/tree_plugin.h:426
 rcu_read_unlock include/linux/rcupdate.h:818 [inline]
 __bpf_trace_run kernel/trace/bpf_trace.c:2323 [inline]
 bpf_trace_run1+0x256/0x3b0 kernel/trace/bpf_trace.c:2360
 __bpf_trace_rcu_utilization+0xa2/0xe0 include/trace/events/rcu.h:27
 __traceiter_rcu_utilization+0x70/0xa0 include/trace/events/rcu.h:27
 trace_rcu_utilization+0x179/0x1a0 include/trace/events/rcu.h:27
 rcu_core+0x12d/0x1720 kernel/rcu/tree.c:2439
 handle_softirqs+0x280/0x820 kernel/softirq.c:578
 __do_softirq kernel/softirq.c:612 [inline]
 invoke_softirq kernel/softirq.c:452 [inline]
 __irq_exit_rcu+0xc7/0x190 kernel/softirq.c:661
 irq_exit_rcu+0x9/0x20 kernel/softirq.c:673
 instr_sysvec_irq_work arch/x86/kernel/irq_work.c:17 [inline]
 sysvec_irq_work+0xa1/0xc0 arch/x86/kernel/irq_work.c:17
 </IRQ>
 <TASK>
 asm_sysvec_irq_work+0x1a/0x20 arch/x86/include/asm/idtentry.h:723
RIP: 0010:preempt_schedule_irq+0xb0/0x140 kernel/sched/core.c:7009
Code: 44 24 20 f6 44 24 21 02 74 0b 0f 0b 48 f7 03 08 00 00 00 74 63 bf 01 00 00 00 e8 4b da e5 f6 e8 46 5f 16 f7 fb bf 01 00 00 00 <e8> db b5 ff ff 48 c7 44 24 40 00 00 00 00 9c 8f 44 24 40 8b 44 24
RSP: 0018:ffffc900048af320 EFLAGS: 00000282
RAX: 5090edb31f450200 RBX: 0000000000000000 RCX: 5090edb31f450200
RDX: dffffc0000000000 RSI: ffffffff8aaab9c0 RDI: 0000000000000001
RBP: ffffc900048af3d0 R08: ffffffff8e4a882f R09: 1ffffffff1c95105
R10: dffffc0000000000 R11: fffffbfff1c95106 R12: 0000000000000000
R13: 0000000000000000 R14: dffffc0000000000 R15: 1ffff92000915e64
 irqentry_exit+0x67/0x70 kernel/entry/common.c:438
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:687
RIP: 0010:get_current arch/x86/include/asm/current.h:41 [inline]
RIP: 0010:write_comp_data kernel/kcov.c:244 [inline]
RIP: 0010:__sanitizer_cov_trace_const_cmp4+0x8/0x90 kernel/kcov.c:313
Code: 08 03 00 00 00 48 89 7c 11 10 48 89 74 11 18 48 89 44 11 20 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 f3 0f 1e fa 48 8b 04 24 <65> 48 8b 15 20 2b 7e 7e 65 8b 0d 21 2b 7e 7e 81 e1 00 01 ff 00 74
RSP: 0018:ffffc900048af498 EFLAGS: 00000246
RAX: ffffffff813aa188 RBX: ffffc900048af510 RCX: 0000000000000000
RDX: ffff88802eac0001 RSI: 0000000000000001 RDI: 0000000000000000
RBP: 0000000000000001 R08: ffff88802eac0000 R09: 0000000000000003
R10: 0000000000000004 R11: 0000000000000000 R12: ffffffff81dbf44e
R13: 0000000000000058 R14: dffffc0000000000 R15: 1ffff92000915ea2
 unwind_get_return_address+0x68/0xc0 arch/x86/kernel/unwind_orc.c:369
 arch_stack_walk+0x11d/0x190 arch/x86/kernel/stacktrace.c:26
 stack_trace_save+0x9c/0xe0 kernel/stacktrace.c:122
 kasan_save_stack mm/kasan/common.c:45 [inline]
 kasan_set_track+0x4e/0x70 mm/kasan/common.c:52
 __kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:328
 kasan_slab_alloc include/linux/kasan.h:188 [inline]
 slab_post_alloc_hook+0x6e/0x4d0 mm/slab.h:767
 slab_alloc_node mm/slub.c:3485 [inline]
 slab_alloc mm/slub.c:3493 [inline]
 __kmem_cache_alloc_lru mm/slub.c:3500 [inline]
 kmem_cache_alloc+0x11e/0x2e0 mm/slub.c:3509
 kmem_cache_zalloc include/linux/slab.h:711 [inline]
 lsm_file_alloc security/security.c:612 [inline]
 security_file_alloc+0x34/0x120 security/security.c:2603
 init_file+0x94/0x1f0 fs/file_table.c:161
 alloc_empty_file+0xb7/0x1d0 fs/file_table.c:210
 path_openat+0x100/0x3190 fs/namei.c:3775
 do_filp_open+0x1c5/0x3d0 fs/namei.c:3816
 do_sys_openat2+0x12c/0x1c0 fs/open.c:1419
 do_sys_open fs/open.c:1434 [inline]
 __do_sys_openat fs/open.c:1450 [inline]
 __se_sys_openat fs/open.c:1445 [inline]
 __x64_sys_openat+0x139/0x160 fs/open.c:1445
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7ff649ca7407
Code: 48 89 fa 4c 89 df e8 38 aa 00 00 8b 93 08 03 00 00 59 5e 48 83 f8 fc 74 1a 5b c3 0f 1f 84 00 00 00 00 00 48 8b 44 24 10 0f 05 <5b> c3 0f 1f 80 00 00 00 00 83 e2 39 83 fa 08 75 de e8 23 ff ff ff
RSP: 002b:00007ffe178864f0 EFLAGS: 00000202 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007ff64a35a880 RCX: 00007ff649ca7407
RDX: 0000000000080000 RSI: 00007ffe17886670 RDI: ffffffffffffff9c
RBP: 0000000000000008 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 00005629c33cb7f5
R13: 00005629c33cb7f5 R14: 0000000000000001 R15: 00005629c33e6140
 </TASK>

Crashes (5):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/08/18 03:20 linux-6.6.y bb9c90ab9c5a 1804e95e .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan-perf INFO: rcu detected stall in sys_openat
2025/08/17 17:46 linux-6.6.y bb9c90ab9c5a 1804e95e .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan-perf INFO: rcu detected stall in sys_openat
2025/08/15 12:00 linux-6.6.y bb9c90ab9c5a 1804e95e .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan-perf INFO: rcu detected stall in sys_openat
2025/08/10 01:03 linux-6.6.y 3a8ababb8b6a 32a0e5ed .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan-perf INFO: rcu detected stall in sys_openat
2025/07/10 07:33 linux-6.6.y a5df3a702b2c 956bd956 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: rcu detected stall in sys_openat
* Struck through repros no longer work on HEAD.