INFO: rcu detected stall in inet_frag_destroy

Status: upstream: reported on 2026/03/29 06:28
Reported-by: syzbot+de6c09fe906b3915c85b@syzkaller.appspotmail.com
First crash: 205d, last: 3d10h
▶ ▼ Similar bugs (3)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-5.15 INFO: rcu detected stall in inet_frag_destroy 1 3 53d 178d 0/3 upstream: reported on 2026/04/25 20:23
android-54 BUG: soft lockup in inet_frag_destroy (2) 1 1 582d 582d 0/2 auto-obsoleted due to no activity on 2025/06/15 23:42
android-54 BUG: soft lockup in inet_frag_destroy 1 3 845d 854d 0/2 auto-obsoleted due to no activity on 2024/09/25 04:36

Sample crash report:
rcu: INFO: rcu_preempt detected expedited stalls on CPUs/tasks: { 0-.... } 2685 jiffies s: 186473 root: 0x1/.
rcu: blocking rcu_node structures (internal RCU debug):
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 32648 Comm: syz.3.7911 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026
RIP: 0010:native_save_fl arch/x86/include/asm/irqflags.h:36 [inline]
RIP: 0010:arch_local_save_flags arch/x86/include/asm/irqflags.h:70 [inline]
RIP: 0010:arch_irqs_disabled arch/x86/include/asm/irqflags.h:130 [inline]
RIP: 0010:lock_release+0x58f/0x920 kernel/locking/lockdep.c:5813
Code: 83 f8 01 75 7f 43 c6 44 2f 04 00 48 c7 84 24 80 00 00 00 00 00 00 00 9c 8f 84 24 80 00 00 00 f7 84 24 80 00 00 00 00 02 00 00 <43> c6 44 2f 04 f8 75 70 f7 44 24 50 00 02 00 00 74 01 fb 48 c7 44
RSP: 0018:ffffc90000007100 EFLAGS: 00000046
RAX: 0000000000000001 RBX: d5ffe4242f386eaf RCX: 1b77911cf8ad0500
RDX: 0000000000000005 RSI: ffffffff8a8c2b20 RDI: ffffffff8adf7160
RBP: ffffc90000007210 R08: ffffffff8f00d22f R09: 1ffffffff1e01a45
R10: dffffc0000000000 R11: fffffbfff1e01a46 R12: ffff88802c92a9a8
R13: dffffc0000000000 R14: ffff88802c92a8d0 R15: 1ffff92000000e2c
FS:  00007f92d521b6c0(0000) GS:ffff8880b8c00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000110c38c1ef CR3: 00000000411a3000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000b6e DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
 <IRQ>
 __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:149 [inline]
 _raw_spin_unlock_irqrestore+0x6d/0x120 kernel/locking/spinlock.c:194
 __run_hrtimer kernel/time/hrtimer.c:1747 [inline]
 __hrtimer_run_queues+0x421/0xc90 kernel/time/hrtimer.c:1815
 hrtimer_interrupt+0x399/0x980 kernel/time/hrtimer.c:1877
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1107 [inline]
 __sysvec_apic_timer_interrupt+0x153/0x5a0 arch/x86/kernel/apic/apic.c:1124
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1118 [inline]
 sysvec_apic_timer_interrupt+0x4d/0xc0 arch/x86/kernel/apic/apic.c:1118
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691
RIP: 0010:unwind_next_frame+0x687/0x1fd0 arch/x86/kernel/unwind_orc.c:471
Code: 28 84 c0 74 65 44 89 f1 80 e1 07 38 c1 7c 5b be 02 00 00 00 48 89 14 24 4c 89 f7 e8 13 a2 9a 00 e9 09 15 00 00 48 8b 44 24 40 <80> 3c 28 00 4c 8d 73 38 74 08 4c 89 f7 e8 37 a1 9a 00 49 8b 16 4d
RSP: 0018:ffffc90000007620 EFLAGS: 00000297
RAX: 1ffff92000000ee0 RBX: ffffc900000076c8 RCX: ffffffff8f786e54
RDX: ffffffff901c556c RSI: ffffffff8f786e30 RDI: 0000000000000001
RBP: dffffc0000000000 R08: 0000000000000021 R09: 000000000000000d
R10: dffffc0000000000 R11: fffff52000000ee5 R12: ffffffff901c559c
R13: ffffffff901c55a0 R14: 0000000000000005 R15: 1ffffffff2038ab4
 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:46 [inline]
 kasan_set_track+0x4b/0x70 mm/kasan/common.c:53
 kasan_save_free_info+0x27/0x40 mm/kasan/generic.c:516
 ____kasan_slab_free+0x126/0x1f0 mm/kasan/common.c:237
 kasan_slab_free include/linux/kasan.h:177 [inline]
 slab_free_hook mm/slub.c:1729 [inline]
 slab_free_freelist_hook+0x133/0x1b0 mm/slub.c:1755
 slab_free mm/slub.c:3687 [inline]
 kmem_cache_free+0xf7/0x2a0 mm/slub.c:3709
 kfree_skb include/linux/skbuff.h:1252 [inline]
 inet_frag_rbtree_purge net/ipv4/inet_fragment.c:280 [inline]
 inet_frag_destroy+0x13d/0x230 net/ipv4/inet_fragment.c:300
 call_timer_fn+0x1ac/0x670 kernel/time/timer.c:1701
 expire_timers kernel/time/timer.c:1752 [inline]
 __run_timers+0x56c/0x810 kernel/time/timer.c:2023
 run_timer_softirq+0x63/0xf0 kernel/time/timer.c:2036
 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:trace_lock_release include/trace/events/lock.h:69 [inline]
RIP: 0010:lock_release+0x86c/0x920 kernel/locking/lockdep.c:5801
Code: 83 90 f8 ff ff 65 ff 05 5a e3 9d 7e 48 c7 c0 d8 ac ec 8e 48 c1 e8 03 42 80 3c 28 00 74 0c 48 c7 c7 d8 ac ec 8e e8 64 16 6f 00 <48> 8b 1d c5 20 88 0d 48 85 db 74 35 48 83 c3 08 48 89 d8 48 c1 e8
RSP: 0018:ffffc90005706840 EFLAGS: 00000246
RAX: 1ffffffff1dd959b RBX: 0000000000000000 RCX: ffffffff81648bcc
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff8f00d228
RBP: ffffc90005706950 R08: ffffffff8f00d22f R09: 1ffffffff1e01a45
R10: dffffc0000000000 R11: fffffbfff1e01a46 R12: 1ffff92000ae0d14
R13: dffffc0000000000 R14: 0000000000000000 R15: 1ffff92000ae0d14
 rcu_lock_release include/linux/rcupdate.h:355 [inline]
 rcu_read_unlock include/linux/rcupdate.h:824 [inline]
 trace_call_bpf+0x5ca/0x6b0 kernel/trace/bpf_trace.c:137
 perf_trace_run_bpf_submit+0x79/0x1c0 kernel/events/core.c:10037
 perf_trace_lock_acquire+0x342/0x3f0 include/trace/events/lock.h:24
 trace_lock_acquire include/trace/events/lock.h:24 [inline]
 lock_acquire+0x452/0x4a0 kernel/locking/lockdep.c:5761
 rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
 rcu_read_lock include/linux/rcupdate.h:791 [inline]
 d_alloc_parallel+0x373/0x1590 fs/dcache.c:2655
 __lookup_slow+0x134/0x3f0 fs/namei.c:1683
 lookup_one_len+0x19d/0x2d0 fs/namei.c:2791
 start_creating+0x184/0x310 fs/debugfs/inode.c:377
 __debugfs_create_file+0x6f/0x500 fs/debugfs/inode.c:422
 debugfs_hw_add+0xb1/0x3a0 net/mac80211/debugfs.c:647
 ieee80211_register_hw+0x2e55/0x3b00 net/mac80211/main.c:1400
 mac80211_hwsim_new_radio+0x2927/0x4cd0 drivers/net/wireless/mac80211_hwsim.c:4592
 hwsim_new_radio_nl+0xab7/0xc90 drivers/net/wireless/mac80211_hwsim.c:5190
 genl_family_rcv_msg_doit+0x22f/0x350 net/netlink/genetlink.c:756
 genl_family_rcv_msg net/netlink/genetlink.c:833 [inline]
 genl_rcv_msg+0x601/0x790 net/netlink/genetlink.c:850
 netlink_rcv_skb+0x1ef/0x440 net/netlink/af_netlink.c:2516
 genl_rcv+0x24/0x40 net/netlink/genetlink.c:861
 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
 netlink_unicast+0x7ad/0x920 net/netlink/af_netlink.c:1344
 netlink_sendmsg+0x8ad/0xbd0 net/netlink/af_netlink.c:1877
 sock_sendmsg_nosec net/socket.c:718 [inline]
 __sock_sendmsg net/socket.c:730 [inline]
 ____sys_sendmsg+0x5ed/0x9a0 net/socket.c:2519
 ___sys_sendmsg+0x2a2/0x360 net/socket.c:2573
 __sys_sendmsg net/socket.c:2602 [inline]
 __do_sys_sendmsg net/socket.c:2611 [inline]
 __se_sys_sendmsg+0x1c3/0x2b0 net/socket.c:2609
 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: 0033:0x7f92d439e559
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:00007f92d521b028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f92d4625fa0 RCX: 00007f92d439e559
RDX: 0000000000000000 RSI: 0000200000001b80 RDI: 000000000000000d
RBP: 00007f92d4435ab8 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f92d4626038 R14: 00007f92d4625fa0 R15: 00007ffea002a438
 </TASK>

Crashes (6):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/10/17 17:00 linux-6.1.y 79807e970724 432c0077 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-perf INFO: rcu detected stall in inet_frag_destroy
2026/07/27 20:34 linux-6.1.y dc5c83b7f5f8 aae9036b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-perf INFO: rcu detected stall in inet_frag_destroy
2026/06/26 04:47 linux-6.1.y fdb6fcb41cc7 7ff32d8b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-perf INFO: rcu detected stall in inet_frag_destroy
2026/05/27 04:42 linux-6.1.y dcbcab9d7079 2b01f00e .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-perf INFO: rcu detected stall in inet_frag_destroy
2026/05/22 04:59 linux-6.1.y c27210688955 70ae9b03 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-perf INFO: rcu detected stall in inet_frag_destroy
2026/03/29 06:27 linux-6.1.y 1989cd3d56e2 b5ceaad2 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-perf INFO: rcu detected stall in inet_frag_destroy
* Struck through repros no longer work on HEAD.