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INFO: rcu detected stall in sock_write_iter (3)

Status: upstream: reported on 2026/05/26 07:14
Reported-by: syzbot+404e8ee8fef0d60fa417@syzkaller.appspotmail.com
First crash: 56d, last: 3d01h
▶ ▼ Similar bugs (12)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-5.15 INFO: rcu detected stall in sock_write_iter (4) origin:lts-only 1 syz done 11 2d03h 492d 0/3 upstream: reported syz repro on 2025/03/16 07:14
linux-6.6 INFO: rcu detected stall in sock_write_iter origin:upstream missing-backport 1 C inconclusive 12 37d 321d 0/2 upstream: reported C repro on 2025/09/03 11:54
upstream INFO: rcu detected stall in sock_write_iter mm 1 1 2422d 2422d 0/29 closed as invalid on 2019/12/04 14:04
linux-5.15 INFO: rcu detected stall in sock_write_iter (3) 1 1 636d 636d 0/3 auto-obsoleted due to no activity on 2025/01/31 00:48
upstream INFO: rcu detected stall in sock_write_iter (3) net prio:low 1 C done error 219 15d 805d 0/29 upstream: reported C repro on 2024/05/07 12:14
linux-5.15 INFO: rcu detected stall in sock_write_iter 1 1 1005d 1005d 0/3 auto-obsoleted due to no activity on 2024/01/28 05:21
linux-5.15 INFO: rcu detected stall in sock_write_iter (2) 1 1 823d 823d 0/3 auto-obsoleted due to no activity on 2024/07/28 08:46
linux-6.1 INFO: rcu detected stall in sock_write_iter 1 1 838d 838d 0/3 auto-obsoleted due to no activity on 2024/07/13 13:13
upstream INFO: rcu detected stall in sock_write_iter (2) netfilter 1 1 990d 990d 0/29 auto-obsoleted due to no activity on 2024/01/03 00:51
linux-6.1 INFO: rcu detected stall in sock_write_iter (2) 1 2 183d 247d 0/3 auto-obsoleted due to no activity on 2026/04/29 05:14
android-5-10 BUG: soft lockup in sock_write_iter 1 1 496d 496d 0/2 auto-obsoleted due to no activity on 2025/06/10 11:55
android-5-15 BUG: soft lockup in sock_write_iter 1 24 706d 842d 0/2 auto-obsoleted due to no activity on 2024/11/03 03:04

Sample crash report:
rcu: INFO: rcu_preempt detected expedited stalls on CPUs/tasks: { 1-.... } 2675 jiffies s: 359709 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: 32671 Comm: syz.4.19811 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
RIP: 0010:kasan_check_range+0x1b2/0x290 mm/kasan/generic.c:-1
Code: 01 f3 49 89 df 49 8d 5f 07 4d 85 ff 49 0f 49 df 48 83 e3 f8 49 29 df 74 0e 41 80 3b 00 75 69 49 ff c3 49 ff cf 75 f2 5b 41 5c <41> 5e 41 5f 5d c3 45 84 ff 0f 85 91 00 00 00 41 f7 c7 00 ff 00 00
RSP: 0018:ffffc900001dfe00 EFLAGS: 00000056
RAX: 0000000000000001 RBX: 0000000000000001 RCX: ffffffff8164022e
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff90b10240
RBP: ffffc900001e0050 R08: ffffffff90b10247 R09: 1ffffffff2162048
R10: dffffc0000000000 R11: fffffbfff2162049 R12: ffff888028ae46d8
R13: ffff888028ae4728 R14: 1ffffffff2162048 R15: 0000000000000001
FS:  00007f9f314ea6c0(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000020000000a000 CR3: 00000000341b5000 CR4: 00000000003506e0
DR0: 0000200000000300 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000200000000300 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
 <IRQ>
 instrument_atomic_read include/linux/instrumented.h:72 [inline]
 _test_bit include/asm-generic/bitops/instrumented-non-atomic.h:141 [inline]
 hlock_class kernel/locking/lockdep.c:228 [inline]
 check_wait_context kernel/locking/lockdep.c:4753 [inline]
 __lock_acquire+0x92e/0x7c40 kernel/locking/lockdep.c:5013
 lock_acquire+0x1bb/0x4a0 kernel/locking/lockdep.c:5676
 rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
 rcu_read_lock_sched include/linux/rcupdate.h:883 [inline]
 pfn_valid include/linux/mmzone.h:1857 [inline]
 __virt_addr_valid+0x1a5/0x540 arch/x86/mm/physaddr.c:65
 kasan_addr_to_slab+0x9/0xc0 mm/kasan/common.c:36
 __kasan_record_aux_stack+0xf/0xc0 mm/kasan/generic.c:471
 irq_work_queue_on+0x10f/0x260 kernel/irq_work.c:140
 rcu_read_unlock_special+0x3c9/0x510 kernel/rcu/tree_plugin.h:678
 __rcu_read_unlock+0x78/0xd0 kernel/rcu/tree_plugin.h:426
 rcu_read_unlock include/linux/rcupdate.h:823 [inline]
 __perf_event_output kernel/events/core.c:7741 [inline]
 perf_event_output_forward+0x271/0x2f0 kernel/events/core.c:7750
 __perf_event_overflow+0x457/0x630 kernel/events/core.c:9496
 perf_swevent_overflow+0x19b/0x230 kernel/events/core.c:9579
 perf_swevent_event+0x458/0x570 kernel/events/core.c:-1
 perf_tp_event+0x36b/0xc10 kernel/events/core.c:10064
 perf_trace_run_bpf_submit+0xf3/0x1c0 kernel/events/core.c:10032
 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 52 82 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: a1c280326dd74b00 RBX: 1ffff9200003c164 RCX: a1c280326dd74b00
RDX: dffffc0000000000 RSI: ffffffff8a8c17a0 RDI: ffffffff8adf42e0
RBP: ffffc900001e0bd0 R08: ffff8880b8f3580b R09: 1ffff110171e6b01
R10: dffffc0000000000 R11: ffffed10171e6b02 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:2147
 __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:copy_user_enhanced_fast_string+0xa/0x40 arch/x86/lib/copy_user_64.S:166
Code: ff c9 75 f2 89 d1 c1 e9 03 83 e2 07 f3 48 a5 89 d1 f3 a4 31 c0 0f 01 ca c3 8d 0c ca 89 ca eb 20 0f 01 cb 83 fa 40 72 38 89 d1 <f3> a4 31 c0 0f 01 ca c3 89 ca eb 0a 90 90 90 90 90 90 90 90 90 90
RSP: 0018:ffffc90005757958 EFLAGS: 00050206
RAX: ffffffff84132d01 RBX: ffffc90005839000 RCX: 0000000000005e73
RDX: 000000000000fe33 RSI: 000020000000a000 RDI: ffffc90005842fc0
RBP: ffffc90005757a90 R08: ffffc90005848e32 R09: 1ffff92000b091c6
R10: dffffc0000000000 R11: fffff52000b091c7 R12: 1ffff92000aeaf83
R13: 0000200000000040 R14: 000000000000fe33 R15: 00007ffffffef1cd
 copy_user_generic arch/x86/include/asm/uaccess_64.h:37 [inline]
 raw_copy_from_user arch/x86/include/asm/uaccess_64.h:52 [inline]
 copyin lib/iov_iter.c:183 [inline]
 _copy_from_iter+0x2a9/0x1130 lib/iov_iter.c:632
 copy_from_iter include/linux/uio.h:187 [inline]
 copy_from_iter_full include/linux/uio.h:194 [inline]
 memcpy_from_msg include/linux/skbuff.h:4076 [inline]
 netlink_sendmsg+0x755/0xbd0 net/netlink/af_netlink.c:1862
 sock_sendmsg_nosec net/socket.c:718 [inline]
 __sock_sendmsg net/socket.c:730 [inline]
 sock_write_iter+0x2d5/0x3e0 net/socket.c:1144
 call_write_iter include/linux/fs.h:2265 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x482/0x9a0 fs/read_write.c:584
 ksys_write+0x14d/0x260 fs/read_write.c:637
 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: 0033:0x7f9f3059de99
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:00007f9f314ea028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f9f30825fa0 RCX: 00007f9f3059de99
RDX: 000000000000fe33 RSI: 0000200000000040 RDI: 0000000000000009
RBP: 00007f9f30633eaf R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f9f30826038 R14: 00007f9f30825fa0 R15: 00007ffe37488d88
 </TASK>

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/07/18 15:13 linux-6.1.y 090666d3cc90 72524a66 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-perf INFO: rcu detected stall in sock_write_iter
2026/05/26 07:13 linux-6.1.y dcbcab9d7079 c69befb3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-perf INFO: rcu detected stall in sock_write_iter
* Struck through repros no longer work on HEAD.