syzbot

 sign-in | mailing list | source | docs
🐞 Open [858]
🐞 Fixed [87]
🐞 Invalid [1359]
⬇ Missing Backports [132]
≡ Crashes
Kernel Health Bugs/Month Bug Lifetimes Fuzzing
💬 Send us feedback

INFO: rcu detected stall in sock_alloc_file (2)

Status: upstream: reported on 2025/10/24 19:33
Reported-by: syzbot+adbc0bd310742910f945@syzkaller.appspotmail.com
First crash: 240d, last: 10d
▶ ▼ Similar bugs (8)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.6 INFO: rcu detected stall in sock_alloc_file (2) 1 1 198d 198d 0/2 auto-obsoleted due to no activity on 2026/03/15 04:14
linux-6.6 INFO: rcu detected stall in sock_alloc_file 1 1 300d 300d 0/2 auto-obsoleted due to no activity on 2025/12/03 21:35
upstream INFO: rcu detected stall in sock_alloc_file fs 1 1 940d 940d 0/29 closed as invalid on 2024/02/01 10:31
upstream INFO: rcu detected stall in sock_alloc_file (3) mm 1 5 210d 346d 0/29 auto-obsoleted due to no activity on 2026/02/21 17:58
linux-5.15 INFO: rcu detected stall in sock_alloc_file 1 1 351d 351d 0/3 auto-obsoleted due to no activity on 2025/10/13 16:41
upstream INFO: rcu detected stall in sock_alloc_file (2) mm 1 6 518d 571d 0/29 auto-obsoleted due to no activity on 2025/04/19 00:40
linux-6.1 INFO: rcu detected stall in sock_alloc_file (2) 1 2 2d22h 81d 0/3 upstream: reported on 2026/04/01 17:08
linux-6.1 INFO: rcu detected stall in sock_alloc_file 1 1 291d 291d 0/3 auto-obsoleted due to no activity on 2025/12/12 11:49

Sample crash report:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	0-...!: (0 ticks this GP) idle=2b5/1/0x4000000000000002 softirq=15738/15738 fqs=0 
	(detected by 1, t=10506 jiffies, g=20101, q=2283)
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 7014 Comm: syz.1.846 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
RIP: 0010:lock_is_held_type+0xef/0x190 kernel/locking/lockdep.c:-1
Code: 8c 4c 89 e6 e8 22 ca 46 fa eb cb 31 ed eb 20 83 fd ff 74 16 89 e9 31 c0 41 f6 47 22 03 0f 95 c0 31 ed 39 c1 40 0f 94 c5 eb 05 <bd> 01 00 00 00 48 c7 c7 20 44 2b 8a e8 c0 0d 00 00 b8 ff ff ff ff
RSP: 0018:ffffc90000007690 EFLAGS: 00000046
RAX: 0000000000000001 RBX: ffff88807e823b80 RCX: 0000000000000001
RDX: 0000000000000100 RSI: ffffffff8c31f360 RDI: ffff88807e824670
RBP: 00000000ffffffff R08: ffffc90000007877 R09: ffffc90000007840
R10: dffffc0000000000 R11: fffff52000000f0f R12: 0000000000000000
R13: 0000000000000046 R14: ffffffff8c31f360 R15: ffff88807e824670
FS:  00007fc8eb2006c0(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b32b1eff8 CR3: 000000001ecbb000 CR4: 00000000003506f0
DR0: 0000200000000300 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
 <IRQ>
 perf_get_guest_cbs include/linux/perf_event.h:1274 [inline]
 perf_misc_flags+0x56/0x1b0 arch/x86/events/core.c:2961
 perf_prepare_sample+0x132/0x1cd0 kernel/events/core.c:7622
 __perf_event_output kernel/events/core.c:7802 [inline]
 perf_event_output_forward+0x185/0x2e0 kernel/events/core.c:7822
 __perf_event_overflow+0x364/0x530 kernel/events/core.c:9515
 perf_tp_event+0x383/0xbf0 kernel/events/core.c:10047
 perf_trace_run_bpf_submit+0xf3/0x1c0 kernel/events/core.c:10021
 perf_trace_preemptirq_template+0x2aa/0x360 include/trace/events/preemptirq.h:14
 trace_irq_enable_rcuidle+0x108/0x180 include/trace/events/preemptirq.h:40
 trace_hardirqs_on+0x57/0x80 kernel/trace/trace_preemptirq.c:44
 asm_sysvec_irq_work+0x16/0x20 arch/x86/include/asm/idtentry.h:713
RIP: 0010:ffs arch/x86/include/asm/bitops.h:297 [inline]
RIP: 0010:handle_softirqs+0x1a9/0x830 kernel/softirq.c:564
Code: 24 78 44 89 64 24 28 0f b7 db 48 c7 c7 80 19 2a 8a e8 6b 27 74 08 65 66 c7 05 11 35 ba 7e 00 00 e8 5c 11 36 00 fb 89 5c 24 34 <b8> ff ff ff ff 0f bc 44 24 34 41 89 c5 41 ff c5 0f 85 d2 00 00 00
RSP: 0018:ffffc90000007e20 EFLAGS: 00000282
RAX: af6e95f307b0da00 RBX: 0000000000000200 RCX: af6e95f307b0da00
RDX: dffffc0000000000 RSI: ffffffff8a2b3180 RDI: ffffffff8a7a09c0
RBP: ffffc90000007f30 R08: ffff8880b903b30b R09: 1ffff11017207661
R10: dffffc0000000000 R11: ffffed1017207662 R12: 000000000000000a
R13: 0000000000000000 R14: ffff88807e823b80 R15: dffffc0000000000
 __do_softirq kernel/softirq.c:610 [inline]
 invoke_softirq kernel/softirq.c:450 [inline]
 __irq_exit_rcu+0x13b/0x230 kernel/softirq.c:659
 irq_exit_rcu+0x5/0x20 kernel/softirq.c:671
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline]
 sysvec_apic_timer_interrupt+0xa0/0xc0 arch/x86/kernel/apic/apic.c:1108
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:native_save_fl arch/x86/include/asm/irqflags.h:35 [inline]
RIP: 0010:arch_local_save_flags arch/x86/include/asm/irqflags.h:70 [inline]
RIP: 0010:arch_local_irq_save arch/x86/include/asm/irqflags.h:106 [inline]
RIP: 0010:rcu_read_unlock_special+0xd6/0x4a0 kernel/rcu/tree_plugin.h:635
Code: 4e 03 00 00 48 8d 65 d8 5b 41 5c 41 5d 41 5e 41 5f 5d c3 49 89 ff 42 c6 44 2b 08 00 48 c7 44 24 60 00 00 00 00 9c 8f 44 24 60 <4c> 8b 64 24 60 42 c6 44 2b 08 f8 fa 41 f7 c4 00 02 00 00 74 0f e8
RSP: 0018:ffffc90002f3f6e0 EFLAGS: 00000246
RAX: f2f2f2f8f1f1f1f1 RBX: 1ffff920005e7ee0 RCX: 0000000000080000
RDX: ffffc900052b1000 RSI: 000000000000860e RDI: ffff88807e823b80
RBP: ffffc90002f3f7c0 R08: dffffc0000000000 R09: 1ffffffff203b018
R10: dffffc0000000000 R11: fffffbfff203b019 R12: 1ffff1100fd047f7
R13: dffffc0000000000 R14: 0000000080000000 R15: ffff88807e823b80
 __rcu_read_unlock+0x78/0xd0 kernel/rcu/tree_plugin.h:422
 rcu_read_unlock include/linux/rcupdate.h:772 [inline]
 is_bpf_text_address+0x24f/0x270 kernel/bpf/core.c:727
 kernel_text_address kernel/extable.c:151 [inline]
 __kernel_text_address+0x9a/0x100 kernel/extable.c:105
 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 mm/kasan/common.c:38 [inline]
 kasan_set_track mm/kasan/common.c:46 [inline]
 set_alloc_info mm/kasan/common.c:434 [inline]
 __kasan_slab_alloc+0x9c/0xd0 mm/kasan/common.c:467
 kasan_slab_alloc include/linux/kasan.h:254 [inline]
 slab_post_alloc_hook+0x4c/0x380 mm/slab.h:519
 slab_alloc_node mm/slub.c:3225 [inline]
 slab_alloc mm/slub.c:3233 [inline]
 kmem_cache_alloc+0x100/0x290 mm/slub.c:3238
 kmem_cache_zalloc include/linux/slab.h:728 [inline]
 __alloc_file+0x25/0x240 fs/file_table.c:132
 alloc_empty_file+0x90/0x180 fs/file_table.c:181
 alloc_file+0x5b/0x4f0 fs/file_table.c:223
 alloc_file_pseudo+0x180/0x200 fs/file_table.c:263
 sock_alloc_file+0xb3/0x240 net/socket.c:464
 __sys_socketpair+0x2cc/0x540 net/socket.c:1675
 __do_sys_socketpair net/socket.c:1704 [inline]
 __se_sys_socketpair net/socket.c:1701 [inline]
 __x64_sys_socketpair+0x97/0xb0 net/socket.c:1701
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7fc8ecfa6e59
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:00007fc8eb200028 EFLAGS: 00000246 ORIG_RAX: 0000000000000035
RAX: ffffffffffffffda RBX: 00007fc8ed21ffa0 RCX: 00007fc8ecfa6e59
RDX: 0000000000000000 RSI: 0000000000000005 RDI: 0000000000000001
RBP: 00007fc8ed03cd6f R08: 0000000000000000 R09: 0000000000000000
R10: 00002000000001c0 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fc8ed220038 R14: 00007fc8ed21ffa0 R15: 00007fffd19db738
 </TASK>
rcu: rcu_preempt kthread timer wakeup didn't happen for 10505 jiffies! g20101 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402
rcu: 	Possible timer handling issue on cpu=0 timer-softirq=10598
rcu: rcu_preempt kthread starved for 10506 jiffies! g20101 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->cpu=0
rcu: 	Unless rcu_preempt kthread gets sufficient CPU time, OOM is now expected behavior.
rcu: RCU grace-period kthread stack dump:
task:rcu_preempt     state:I stack:27504 pid:   15 ppid:     2 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5049 [inline]
 __schedule+0x11ef/0x43c0 kernel/sched/core.c:6395
 schedule+0x11b/0x1e0 kernel/sched/core.c:6478
 schedule_timeout+0x184/0x2d0 kernel/time/timer.c:2117
 rcu_gp_fqs_loop+0x2be/0x11d0 kernel/rcu/tree.c:1972
 rcu_gp_kthread+0x9b/0x370 kernel/rcu/tree.c:2145
 kthread+0x436/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 7014 Comm: syz.1.846 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
RIP: 0010:hlock_class kernel/locking/lockdep.c:192 [inline]
RIP: 0010:check_wait_context kernel/locking/lockdep.c:4711 [inline]
RIP: 0010:__lock_acquire+0x8f6/0x7d10 kernel/locking/lockdep.c:4962
Code: c0 88 3a 8a 8d 48 c1 e8 03 48 89 84 24 b0 00 00 00 4d 89 e7 48 83 fb 31 0f 83 52 01 00 00 4c 89 f8 48 c1 e8 03 42 0f b6 04 00 <84> c0 0f 85 5c 01 00 00 41 8b 04 24 41 89 c6 41 81 e6 ff 1f 00 00
RSP: 0018:ffffc90000007300 EFLAGS: 00000806
RAX: 0000000000000000 RBX: 0000000000000001 RCX: ffff88807e823b80
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff901d80c0
RBP: ffffc90000007550 R08: dffffc0000000000 R09: 1ffffffff203b018
R10: dffffc0000000000 R11: fffffbfff203b019 R12: ffff88807e8246b8
R13: ffff88807e824602 R14: 0000000000000001 R15: ffff88807e8246b8
FS:  00007fc8eb2006c0(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b32b1eff8 CR3: 000000001ecbb000 CR4: 00000000003506f0
DR0: 0000200000000300 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
 <IRQ>
 lock_acquire+0x19e/0x400 kernel/locking/lockdep.c:5623
 rcu_lock_acquire+0x2a/0x30 include/linux/rcupdate.h:313
 rcu_read_lock include/linux/rcupdate.h:740 [inline]
 __perf_output_begin kernel/events/ring_buffer.c:163 [inline]
 perf_output_begin_forward+0xa5/0xa40 kernel/events/ring_buffer.c:271
 __perf_event_output kernel/events/core.c:7804 [inline]
 perf_event_output_forward+0x19b/0x2e0 kernel/events/core.c:7822
 __perf_event_overflow+0x364/0x530 kernel/events/core.c:9515
 perf_tp_event+0x383/0xbf0 kernel/events/core.c:10047
 perf_trace_run_bpf_submit+0xf3/0x1c0 kernel/events/core.c:10021
 perf_trace_preemptirq_template+0x2aa/0x360 include/trace/events/preemptirq.h:14
 trace_irq_enable_rcuidle+0x108/0x180 include/trace/events/preemptirq.h:40
 trace_hardirqs_on+0x57/0x80 kernel/trace/trace_preemptirq.c:44
 asm_sysvec_irq_work+0x16/0x20 arch/x86/include/asm/idtentry.h:713
RIP: 0010:ffs arch/x86/include/asm/bitops.h:297 [inline]
RIP: 0010:handle_softirqs+0x1a9/0x830 kernel/softirq.c:564
Code: 24 78 44 89 64 24 28 0f b7 db 48 c7 c7 80 19 2a 8a e8 6b 27 74 08 65 66 c7 05 11 35 ba 7e 00 00 e8 5c 11 36 00 fb 89 5c 24 34 <b8> ff ff ff ff 0f bc 44 24 34 41 89 c5 41 ff c5 0f 85 d2 00 00 00
RSP: 0018:ffffc90000007e20 EFLAGS: 00000282
RAX: af6e95f307b0da00 RBX: 0000000000000200 RCX: af6e95f307b0da00
RDX: dffffc0000000000 RSI: ffffffff8a2b3180 RDI: ffffffff8a7a09c0
RBP: ffffc90000007f30 R08: ffff8880b903b30b R09: 1ffff11017207661
R10: dffffc0000000000 R11: ffffed1017207662 R12: 000000000000000a
R13: 0000000000000000 R14: ffff88807e823b80 R15: dffffc0000000000
 __do_softirq kernel/softirq.c:610 [inline]
 invoke_softirq kernel/softirq.c:450 [inline]
 __irq_exit_rcu+0x13b/0x230 kernel/softirq.c:659
 irq_exit_rcu+0x5/0x20 kernel/softirq.c:671
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline]
 sysvec_apic_timer_interrupt+0xa0/0xc0 arch/x86/kernel/apic/apic.c:1108
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:native_save_fl arch/x86/include/asm/irqflags.h:35 [inline]
RIP: 0010:arch_local_save_flags arch/x86/include/asm/irqflags.h:70 [inline]
RIP: 0010:arch_local_irq_save arch/x86/include/asm/irqflags.h:106 [inline]
RIP: 0010:rcu_read_unlock_special+0xd6/0x4a0 kernel/rcu/tree_plugin.h:635
Code: 4e 03 00 00 48 8d 65 d8 5b 41 5c 41 5d 41 5e 41 5f 5d c3 49 89 ff 42 c6 44 2b 08 00 48 c7 44 24 60 00 00 00 00 9c 8f 44 24 60 <4c> 8b 64 24 60 42 c6 44 2b 08 f8 fa 41 f7 c4 00 02 00 00 74 0f e8
RSP: 0018:ffffc90002f3f6e0 EFLAGS: 00000246
RAX: f2f2f2f8f1f1f1f1 RBX: 1ffff920005e7ee0 RCX: 0000000000080000
RDX: ffffc900052b1000 RSI: 000000000000860e RDI: ffff88807e823b80
RBP: ffffc90002f3f7c0 R08: dffffc0000000000 R09: 1ffffffff203b018
R10: dffffc0000000000 R11: fffffbfff203b019 R12: 1ffff1100fd047f7
R13: dffffc0000000000 R14: 0000000080000000 R15: ffff88807e823b80
 __rcu_read_unlock+0x78/0xd0 kernel/rcu/tree_plugin.h:422
 rcu_read_unlock include/linux/rcupdate.h:772 [inline]
 is_bpf_text_address+0x24f/0x270 kernel/bpf/core.c:727
 kernel_text_address kernel/extable.c:151 [inline]
 __kernel_text_address+0x9a/0x100 kernel/extable.c:105
 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 mm/kasan/common.c:38 [inline]
 kasan_set_track mm/kasan/common.c:46 [inline]
 set_alloc_info mm/kasan/common.c:434 [inline]
 __kasan_slab_alloc+0x9c/0xd0 mm/kasan/common.c:467
 kasan_slab_alloc include/linux/kasan.h:254 [inline]
 slab_post_alloc_hook+0x4c/0x380 mm/slab.h:519
 slab_alloc_node mm/slub.c:3225 [inline]
 slab_alloc mm/slub.c:3233 [inline]
 kmem_cache_alloc+0x100/0x290 mm/slub.c:3238
 kmem_cache_zalloc include/linux/slab.h:728 [inline]
 __alloc_file+0x25/0x240 fs/file_table.c:132
 alloc_empty_file+0x90/0x180 fs/file_table.c:181
 alloc_file+0x5b/0x4f0 fs/file_table.c:223
 alloc_file_pseudo+0x180/0x200 fs/file_table.c:263
 sock_alloc_file+0xb3/0x240 net/socket.c:464
 __sys_socketpair+0x2cc/0x540 net/socket.c:1675
 __do_sys_socketpair net/socket.c:1704 [inline]
 __se_sys_socketpair net/socket.c:1701 [inline]
 __x64_sys_socketpair+0x97/0xb0 net/socket.c:1701
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7fc8ecfa6e59
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:00007fc8eb200028 EFLAGS: 00000246 ORIG_RAX: 0000000000000035
RAX: ffffffffffffffda RBX: 00007fc8ed21ffa0 RCX: 00007fc8ecfa6e59
RDX: 0000000000000000 RSI: 0000000000000005 RDI: 0000000000000001
RBP: 00007fc8ed03cd6f R08: 0000000000000000 R09: 0000000000000000
R10: 00002000000001c0 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fc8ed220038 R14: 00007fc8ed21ffa0 R15: 00007fffd19db738
 </TASK>

Crashes (6):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/06/11 20:45 linux-5.15.y dc027a595035 d93a6ab6 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf INFO: rcu detected stall in sock_alloc_file
2026/04/12 22:41 linux-5.15.y 91d48252ad4b 38c8e246 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf INFO: rcu detected stall in sock_alloc_file
2026/02/27 23:35 linux-5.15.y 3330a8d33e08 2cf092b8 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf INFO: rcu detected stall in sock_alloc_file
2025/12/24 03:15 linux-5.15.y 68efe5a6c16a d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf INFO: rcu detected stall in sock_alloc_file
2025/11/30 01:31 linux-5.15.y cc5ec8769306 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf INFO: rcu detected stall in sock_alloc_file
2025/10/24 19:33 linux-5.15.y ac56c046adf4 c0460fcd .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf INFO: rcu detected stall in sock_alloc_file
* Struck through repros no longer work on HEAD.