INFO: rcu detected stall in sock_alloc_file (3)

Status: upstream: reported on 2026/10/14 08:55
Reported-by: syzbot+7a6a5fc3681edf1a9da6@syzkaller.appspotmail.com
First crash: 3d18h, last: 3d18h
▶ ▼ Similar bugs (10)
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 316d 316d 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 418d 418d 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 1058d 1058d 0/29 closed as invalid on 2024/02/01 10:31
upstream INFO: rcu detected stall in sock_alloc_file (3) mm 1 5 328d 464d 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 469d 469d 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 637d 689d 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 13 7d01h 199d 0/3 upstream: reported on 2026/04/01 17:08
linux-5.15 INFO: rcu detected stall in sock_alloc_file (2) 1 9 10d 358d 0/3 upstream: reported on 2025/10/24 19:33
linux-6.1 INFO: rcu detected stall in sock_alloc_file 1 1 409d 409d 0/3 auto-obsoleted due to no activity on 2025/12/12 11:49
upstream BUG: soft lockup in sock_alloc_file prio:low mm 1 11 13d 206d 0/29 closed as invalid on 2026/10/06 01:52

Sample crash report:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P5888/1:b..l
rcu: 	(detected by 0, t=10502 jiffies, g=9425, q=926 ncpus=2)
task:syz.2.14        state:R  running task     stack:24840 pid:5888  ppid:5773   flags:0x00004006
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5382 [inline]
 __schedule+0x15ae/0x4660 kernel/sched/core.c:6701
 preempt_schedule_common+0x82/0xc0 kernel/sched/core.c:6868
 preempt_schedule+0xc0/0xd0 kernel/sched/core.c:6892
 preempt_schedule_thunk+0x1a/0x30 arch/x86/entry/thunk_64.S:45
 __local_bh_enable_ip+0x14b/0x1c0 kernel/softirq.c:413
 local_bh_enable include/linux/bottom_half.h:33 [inline]
 xdp_test_run_batch net/bpf/test_run.c:361 [inline]
 bpf_test_run_xdp_live+0x18ce/0x1b30 net/bpf/test_run.c:383
 bpf_prog_test_run_xdp+0x7d8/0x1140 net/bpf/test_run.c:1326
 bpf_prog_test_run+0x31f/0x390 kernel/bpf/syscall.c:4140
 __sys_bpf+0x49d/0x890 kernel/bpf/syscall.c:5512
 __do_sys_bpf kernel/bpf/syscall.c:5598 [inline]
 __se_sys_bpf kernel/bpf/syscall.c:5596 [inline]
 __x64_sys_bpf+0x7c/0x90 kernel/bpf/syscall.c:5596
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fc73e79e2d9
RSP: 002b:00007fc73f717028 EFLAGS: 00000246 ORIG_RAX: 0000000000000141
RAX: ffffffffffffffda RBX: 00007fc73ea26090 RCX: 00007fc73e79e2d9
RDX: 0000000000000048 RSI: 0000200000000580 RDI: 000000000000000a
RBP: 00007fc73e835888 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fc73ea26128 R14: 00007fc73ea26090 R15: 00007ffce24302a8
 </TASK>
rcu: rcu_preempt kthread starved for 9290 jiffies! g9425 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->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:R  running task     stack:26216 pid:17    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5382 [inline]
 __schedule+0x15ae/0x4660 kernel/sched/core.c:6701
 schedule+0xbd/0x170 kernel/sched/core.c:6775
 schedule_timeout+0x188/0x2d0 kernel/time/timer.c:2168
 rcu_gp_fqs_loop+0x30d/0x1590 kernel/rcu/tree.c:1667
 rcu_gp_kthread+0x9d/0x3b0 kernel/rcu/tree.c:1866
 kthread+0x2fa/0x390 kernel/kthread.c:388
 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
CPU: 0 PID: 5892 Comm: syz.1.15 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026
RIP: 0010:seqcount_lockdep_reader_access+0x19a/0x1d0 include/linux/seqlock.h:105
Code: 00 4d 85 e4 75 16 e8 95 cb 0f 00 eb 15 e8 8e cb 0f 00 e8 e9 45 1b 09 4d 85 e4 74 ea e8 7f cb 0f 00 fb 48 c7 04 24 0e 36 e0 45 <4b> c7 04 3e 00 00 00 00 43 c7 44 3e 08 00 00 00 00 65 48 8b 04 25
RSP: 0018:ffffc900000063a0 EFLAGS: 00000246
RAX: ffffffff8177c531 RBX: 0000000000000000 RCX: ffff88802ad80000
RDX: 0000000000000100 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc90000006458 R08: ffffffff91ff152f R09: 1ffffffff23fe2a5
R10: dffffc0000000000 R11: fffffbfff23fe2a6 R12: 0000000000000200
R13: 1ffff92000000c9c R14: 1ffff92000000c74 R15: dffffc0000000000
FS:  00007f483a8e86c0(0000) GS:ffff8880b8c00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f3234bf34b8 CR3: 000000005c981000 CR4: 00000000003506f0
Call Trace:
 <IRQ>
 ktime_get_with_offset+0x94/0x330 kernel/time/timekeeping.c:889
 ktime_get_real include/linux/timekeeping.h:79 [inline]
 netif_rx_internal+0x33d/0x4e0 net/core/dev.c:5177
 __netif_rx+0x78/0xc0 net/core/dev.c:5220
 veth_forward_skb drivers/net/veth.c:325 [inline]
 veth_xmit+0x57a/0xa30 drivers/net/veth.c:378
 __netdev_start_xmit include/linux/netdevice.h:4998 [inline]
 netdev_start_xmit include/linux/netdevice.h:5012 [inline]
 xmit_one net/core/dev.c:3649 [inline]
 dev_hard_start_xmit+0x269/0x790 net/core/dev.c:3665
 __dev_queue_xmit+0x1be8/0x37e0 net/core/dev.c:4478
 dev_queue_xmit include/linux/netdevice.h:3170 [inline]
 br_dev_queue_push_xmit+0x6b7/0x880 net/bridge/br_forward.c:53
 NF_HOOK+0x66e/0x700 include/linux/netfilter.h:304
 br_nf_post_routing+0xa3b/0xec0 net/bridge/br_netfilter_hooks.c:981
 nf_hook_entry_hookfn include/linux/netfilter.h:144 [inline]
 nf_hook_slow+0xbd/0x200 net/netfilter/core.c:626
 nf_hook include/linux/netfilter.h:259 [inline]
 NF_HOOK+0x23e/0x3e0 include/linux/netfilter.h:302
 br_forward_finish+0xd3/0x130 net/bridge/br_forward.c:66
 br_nf_hook_thresh net/bridge/br_netfilter_hooks.c:1188 [inline]
 br_nf_forward_finish+0xa69/0xe90 net/bridge/br_netfilter_hooks.c:688
 NF_HOOK+0x66e/0x700 include/linux/netfilter.h:304
 br_nf_forward_ip+0xc78/0x10d0 net/bridge/br_netfilter_hooks.c:758
 nf_hook_entry_hookfn include/linux/netfilter.h:144 [inline]
 nf_hook_slow+0xbd/0x200 net/netfilter/core.c:626
 nf_hook include/linux/netfilter.h:259 [inline]
 NF_HOOK+0x23e/0x3e0 include/linux/netfilter.h:302
 __br_forward+0x433/0x610 net/bridge/br_forward.c:115
 deliver_clone net/bridge/br_forward.c:131 [inline]
 maybe_deliver+0xb5/0x150 net/bridge/br_forward.c:191
 br_flood+0x317/0x670 net/bridge/br_forward.c:237
 br_handle_frame_finish+0xf2d/0x15c0 net/bridge/br_input.c:215
 br_nf_hook_thresh+0x3cd/0x4a0 net/bridge/br_netfilter_hooks.c:1188
 br_nf_pre_routing_finish_ipv6+0x9e5/0xd20 net/bridge/br_netfilter_ipv6.c:-1
 NF_HOOK include/linux/netfilter.h:304 [inline]
 br_nf_pre_routing_ipv6+0x34d/0x6a0 net/bridge/br_netfilter_ipv6.c:184
 nf_hook_entry_hookfn include/linux/netfilter.h:144 [inline]
 nf_hook_bridge_pre net/bridge/br_input.c:277 [inline]
 br_handle_frame+0x1240/0x14d0 net/bridge/br_input.c:424
 __netif_receive_skb_core+0xf94/0x3ac0 net/core/dev.c:5564
 __netif_receive_skb_one_core net/core/dev.c:5668 [inline]
 __netif_receive_skb+0x74/0x290 net/core/dev.c:5784
 process_backlog+0x380/0x710 net/core/dev.c:6112
 __napi_poll+0xbb/0x460 net/core/dev.c:6674
 napi_poll net/core/dev.c:6741 [inline]
 net_rx_action+0x65f/0xcc0 net/core/dev.c:6877
 handle_softirqs+0x27d/0x820 kernel/softirq.c:578
 __do_softirq kernel/softirq.c:612 [inline]
 invoke_softirq kernel/softirq.c:452 [inline]
 __irq_exit_rcu+0xd3/0x190 kernel/softirq.c:661
 irq_exit_rcu+0x9/0x20 kernel/softirq.c:673
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1088 [inline]
 sysvec_apic_timer_interrupt+0xa4/0xc0 arch/x86/kernel/apic/apic.c:1088
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:687
RIP: 0010:qlist_free_all+0x26/0xd0 mm/kasan/quarantine.c:-1
Code: 1f 44 00 00 55 41 57 41 56 41 55 41 54 53 48 8b 2f 48 85 ed 0f 84 af 00 00 00 49 89 f6 48 89 fb 49 bd 00 00 00 00 00 fc ff df <49> 89 ef 4d 89 f4 4d 85 f6 75 0b 4c 89 ff e8 c7 04 00 00 49 89 c4
RSP: 0018:ffffc90004b3fbb0 EFLAGS: 00000286
RAX: 688f2e4f2661a500 RBX: ffffc90004b3fbe8 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000004 RDI: 00000000ffffffff
RBP: ffff88802bab6300 R08: ffff8880b8c42103 R09: 1ffff11017188420
R10: dffffc0000000000 R11: ffffed1017188421 R12: ffff888018842140
R13: dffffc0000000000 R14: 0000000000000000 R15: ffff88802f848000
 kasan_quarantine_reduce+0x143/0x160 mm/kasan/quarantine.c:292
 __kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:306
 kasan_slab_alloc include/linux/kasan.h:188 [inline]
 slab_post_alloc_hook+0x6a/0x4d0 mm/slab.h:770
 slab_alloc_node mm/slub.c:3495 [inline]
 slab_alloc mm/slub.c:3503 [inline]
 __kmem_cache_alloc_lru mm/slub.c:3510 [inline]
 kmem_cache_alloc_lru+0x175/0x2b0 mm/slub.c:3526
 __d_alloc+0x31/0x710 fs/dcache.c:1773
 d_alloc_pseudo+0x1d/0x70 fs/dcache.c:1905
 alloc_file_pseudo+0xe4/0x210 fs/file_table.c:363
 sock_alloc_file+0xb7/0x280 net/socket.c:469
 __sys_socketpair+0x376/0x550 net/socket.c:1809
 __do_sys_socketpair net/socket.c:1831 [inline]
 __se_sys_socketpair net/socket.c:1828 [inline]
 __x64_sys_socketpair+0x9b/0xb0 net/socket.c:1828
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f483999e2d9
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:00007f483a8e8028 EFLAGS: 00000246
 ORIG_RAX: 0000000000000035
RAX: ffffffffffffffda RBX: 00007f4839c25fa0 RCX: 00007f483999e2d9
RDX: 0000000000000000 RSI: 0000000000000005 RDI: 0000000000000001
RBP: 00007f4839a35888 R08: 0000000000000000 R09: 0000000000000000
R10: 0000200000000640 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f4839c26038 R14: 00007f4839c25fa0 R15: 00007ffebc342618
 </TASK>

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/10/14 08:55 linux-6.6.y a91a6aa9253c 7321cd29 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan-perf INFO: rcu detected stall in sock_alloc_file
* Struck through repros no longer work on HEAD.