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INFO: rcu detected stall in sock_read_iter

Status: upstream: reported on 2026/05/27 14:02
Reported-by: syzbot+98e787cc2d005c73fd41@syzkaller.appspotmail.com
First crash: 19d, last: 19d
▶ ▼ Similar bugs (7)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.1 INFO: rcu detected stall in sock_read_iter 1 1 517d 517d 0/3 auto-obsoleted due to no activity on 2025/04/25 05:42
upstream INFO: rcu detected stall in sock_read_iter net 1 1 1348d 1348d 0/29 auto-obsoleted due to no activity on 2022/12/05 11:10
upstream INFO: rcu detected stall in sock_read_iter (2) net 1 1 607d 607d 0/29 auto-obsoleted due to no activity on 2025/01/14 23:11
android-5-15 BUG: soft lockup in sock_read_iter 1 10 668d 799d 0/2 auto-obsoleted due to no activity on 2024/11/14 07:45
android-6-1 BUG: soft lockup in sock_read_iter (2) 1 2 232d 281d 0/2 auto-obsoleted due to no activity on 2026/01/25 06:24
android-6-1 BUG: soft lockup in sock_read_iter 1 2 414d 453d 0/2 auto-obsoleted due to no activity on 2025/07/26 10:57
android-5-10 BUG: soft lockup in sock_read_iter 1 2 339d 351d 0/2 auto-obsoleted due to no activity on 2025/10/10 06:20

Sample crash report:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P3855/1:b..l
	(detected by 0, t=10506 jiffies, g=145357, q=43)
task:dhcpcd          state:R  running task     stack:21328 pid: 3855 ppid:  3854 flags:0x00004002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5049 [inline]
 __schedule+0x11ef/0x43c0 kernel/sched/core.c:6395
 preempt_schedule_irq+0xbb/0x160 kernel/sched/core.c:6799
 irqentry_exit+0x63/0x70 kernel/entry/common.c:432
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:lock_acquire+0x208/0x400 kernel/locking/lockdep.c:5627
Code: f7 84 24 80 00 00 00 00 02 00 00 43 c6 44 3d 04 f8 0f 85 f1 00 00 00 41 f7 c6 00 02 00 00 74 01 fb 48 c7 44 24 60 0e 36 e0 45 <4b> c7 44 3d 00 00 00 00 00 43 c7 44 3d 08 00 00 00 00 65 48 8b 04
RSP: 0018:ffffc9000355f300 EFLAGS: 00000206
RAX: 0000000000000001 RBX: 0000000000000000 RCX: 7bdd75b8f6999b00
RDX: 0000000000000000 RSI: ffffffff8a2b43a0 RDI: ffffffff8a7a0700
RBP: ffffc9000355f420 R08: dffffc0000000000 R09: 1ffffffff203ac18
R10: dffffc0000000000 R11: fffffbfff203ac19 R12: ffffffff8c31f320
R13: 1ffff920006abe6c R14: 0000000000000246 R15: dffffc0000000000
 rcu_lock_acquire+0x2a/0x30 include/linux/rcupdate.h:313
 rcu_read_lock include/linux/rcupdate.h:740 [inline]
 is_bpf_text_address+0x1d/0x270 kernel/bpf/core.c:725
 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+0x4b/0x70 mm/kasan/common.c:46
 kasan_set_free_info+0x1f/0x40 mm/kasan/generic.c:360
 ____kasan_slab_free+0xd5/0x110 mm/kasan/common.c:366
 kasan_slab_free include/linux/kasan.h:230 [inline]
 slab_free_hook mm/slub.c:1710 [inline]
 slab_free_freelist_hook+0xea/0x170 mm/slub.c:1736
 slab_free mm/slub.c:3504 [inline]
 kfree+0xef/0x2a0 mm/slub.c:4564
 skb_free_head net/core/skbuff.c:655 [inline]
 skb_release_data+0x6b8/0x800 net/core/skbuff.c:677
 skb_release_all net/core/skbuff.c:742 [inline]
 __kfree_skb net/core/skbuff.c:756 [inline]
 consume_skb+0xa2/0x100 net/core/skbuff.c:914
 skb_free_datagram+0x25/0xe0 net/core/datagram.c:325
 __unix_dgram_recvmsg+0xa01/0xd90 net/unix/af_unix.c:2395
 sock_recvmsg_nosec net/socket.c:968 [inline]
 sock_recvmsg net/socket.c:986 [inline]
 sock_read_iter+0x2b8/0x380 net/socket.c:1067
 call_read_iter include/linux/fs.h:2167 [inline]
 new_sync_read fs/read_write.c:404 [inline]
 vfs_read+0x759/0xd60 fs/read_write.c:485
 ksys_read+0x152/0x260 fs/read_write.c:623
 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: 0033:0x7f75f6687407
RSP: 002b:00007ffd9f022f60 EFLAGS: 00000202 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 00007f75f65fd740 RCX: 00007f75f6687407
RDX: 0000000000000408 RSI: 00007ffd9f022fb0 RDI: 0000000000000007
RBP: 00007ffd9f0236c0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 00005598e9a585e0
R13: 000055990efe5d90 R14: 0000000000000001 R15: 00007ffd9f023470
 </TASK>
rcu: rcu_preempt kthread timer wakeup didn't happen for 10505 jiffies! g145357 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402
rcu: 	Possible timer handling issue on cpu=1 timer-softirq=75889
rcu: rcu_preempt kthread starved for 10506 jiffies! g145357 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->cpu=1
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:27152 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 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 21923 Comm: kworker/1:1 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
Workqueue: events nsim_dev_trap_report_work
RIP: 0010:hlock_class kernel/locking/lockdep.c:197 [inline]
RIP: 0010:__lock_acquire+0x10c6/0x7d10 kernel/locking/lockdep.c:5008
Code: 03 89 c3 81 e3 ff 1f 00 00 c1 e8 03 25 f8 03 00 00 48 8d b8 c0 60 1d 90 be 08 00 00 00 e8 62 2e 61 00 48 0f a3 1d aa 38 c0 0e <0f> 83 87 01 00 00 48 8d 04 5b c1 e0 06 48 8d 98 80 df b5 8f 49 b8
RSP: 0018:ffffc90000dd08e0 EFLAGS: 00000057
RAX: 0000000000000001 RBX: 00000000000007d9 RCX: ffffffff815d280e
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff901d61b8
RBP: ffffc90000dd0b30 R08: ffffffff901d61bf R09: 1ffffffff203ac37
R10: dffffc0000000000 R11: fffffbfff203ac38 R12: 00000000427a51ed
R13: ffff888046a7bb80 R14: 000000007f23e7e1 R15: ffff888046a7c730
FS:  0000000000000000(0000) GS:ffff8880b9100000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffd9f022fa8 CR3: 0000000023c53000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <IRQ>
 lock_acquire+0x19e/0x400 kernel/locking/lockdep.c:5623
 __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
 _raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:154
 spin_lock include/linux/spinlock.h:364 [inline]
 advance_sched+0x47/0x940 net/sched/sch_taprio.c:716
 __run_hrtimer kernel/time/hrtimer.c:1685 [inline]
 __hrtimer_run_queues+0x4f2/0xb70 kernel/time/hrtimer.c:1749
 hrtimer_interrupt+0x3bb/0x8d0 kernel/time/hrtimer.c:1811
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1097 [inline]
 __sysvec_apic_timer_interrupt+0x137/0x4a0 arch/x86/kernel/apic/apic.c:1114
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline]
 sysvec_apic_timer_interrupt+0x9b/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:memset_erms+0xb/0x10 arch/x86/lib/memset_64.S:65
Code: 03 40 0f b6 f6 48 b8 01 01 01 01 01 01 01 01 48 0f af c6 f3 48 ab 89 d1 f3 aa 4c 89 c8 c3 90 49 89 f9 40 88 f0 48 89 d1 f3 aa <4c> 89 c8 c3 90 49 89 fa 40 0f b6 ce 48 b8 01 01 01 01 01 01 01 01
RSP: 0018:ffffc9000326f600 EFLAGS: 00000202
RAX: 0000000000000000 RBX: ffffc9000326f6c8 RCX: 0000000000000000
RDX: 0000000000000010 RSI: 0000000000000000 RDI: ffffc9000326f728
RBP: ffffc9000326f710 R08: ffffc9000326f727 R09: ffffc9000326f718
R10: dffffc0000000000 R11: fffff5200064dee5 R12: 1ffffffff1c0a23c
R13: dffffc0000000000 R14: ffffc9000326f718 R15: ffffc9000326f6fd
 unwind_next_frame+0xa3d/0x1d90 arch/x86/kernel/unwind_orc.c:547
 arch_stack_walk+0x10c/0x140 arch/x86/kernel/stacktrace.c:25
 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]
 kmem_cache_alloc_node+0x12d/0x2d0 mm/slub.c:3261
 __alloc_skb+0xf4/0x750 net/core/skbuff.c:415
 alloc_skb include/linux/skbuff.h:1162 [inline]
 nsim_dev_trap_skb_build drivers/net/netdevsim/dev.c:664 [inline]
 nsim_dev_trap_report drivers/net/netdevsim/dev.c:721 [inline]
 nsim_dev_trap_report_work+0x2a1/0xb40 drivers/net/netdevsim/dev.c:762
 process_one_work+0x85f/0x1010 kernel/workqueue.c:2310
 worker_thread+0xaa6/0x1290 kernel/workqueue.c:2457
 kthread+0x436/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/05/27 14:01 linux-5.15.y 241d66fa280c 8777bdc3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in sock_read_iter
* Struck through repros no longer work on HEAD.