rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 0-...!: (1 GPs behind) idle=c98c/1/0x4000000000000000 softirq=28615/28618 fqs=23
rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P7762/1:b..l
rcu: (detected by 1, t=10502 jiffies, g=25017, q=659 ncpus=2)
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 7744 Comm: syz.3.404 Tainted: G L syzkaller #0 PREEMPT(full)
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
RIP: 0010:num_possible_cpus include/linux/cpumask.h:1222 [inline]
RIP: 0010:mm_get_cid kernel/sched/sched.h:3839 [inline]
RIP: 0010:sched_mm_cid_fork+0x52a/0xcd0 kernel/sched/core.c:10704
Code: 12 8e 48 b8 00 00 00 00 00 fc ff df 49 c1 ef 03 4c 01 f8 48 89 04 24 eb 5d 49 c7 c4 34 a0 12 8e 41 83 e4 07 41 83 c4 03 f3 90 <48> 8b 04 24 0f b6 00 41 38 c4 7c 08 84 c0 0f 85 4f 06 00 00 8b 35
RSP: 0018:ffffc9000cf4fcf0 EFLAGS: 00000046
RAX: 0000000000000002 RBX: ffff88807d618b90 RCX: 0000000000000000
RDX: 0000000000000002 RSI: 0000000000000002 RDI: ffff88807d618b90
RBP: ffff888032eb8000 R08: 0000000000000001 R09: fffff520019e9f90
R10: 0000000000000003 R11: 0000000000000000 R12: 0000000000000007
R13: ffff88807d618178 R14: 0000000000000002 R15: 0000000000000002
FS: 00007f72ac0576c0(0000) GS:ffff88812434c000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000000000 CR3: 0000000035106000 CR4: 00000000003526f0
Call Trace:
bprm_execve fs/exec.c:1771 [inline]
bprm_execve+0x53f/0x1680 fs/exec.c:1724
do_execveat_common.isra.0+0x4a5/0x580 fs/exec.c:1846
__do_sys_execve fs/exec.c:1930 [inline]
__se_sys_execve fs/exec.c:1924 [inline]
__x64_sys_execve+0x93/0xd0 fs/exec.c:1924
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x106/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f72ab19c799
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:00007f72ac057028 EFLAGS: 00000246 ORIG_RAX: 000000000000003b
RAX: ffffffffffffffda RBX: 00007f72ab416090 RCX: 00007f72ab19c799
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 00002000000000c0
RBP: 00007f72ab232bd9 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f72ab416128 R14: 00007f72ab416090 R15: 00007ffed6a6af68
task:syz.0.410 state:R running task stack:26232 pid:7762 tgid:7761 ppid:6073 task_flags:0x400140 flags:0x00080000
Call Trace:
context_switch kernel/sched/core.c:5295 [inline]
__schedule+0xfee/0x60e0 kernel/sched/core.c:6907
preempt_schedule_irq+0x50/0x90 kernel/sched/core.c:7234
irqentry_exit+0x17b/0x670 kernel/entry/common.c:239
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:lock_acquire+0x5e/0x380 kernel/locking/lockdep.c:5872
Code: 05 3b fe 28 12 83 f8 07 0f 87 f0 00 00 00 48 0f a3 05 06 6e f5 0e 0f 82 c2 02 00 00 8b 35 ce a1 f5 0e 85 f6 0f 85 dd 00 00 00 <48> 8b 44 24 30 65 48 2b 05 dd fd 28 12 0f 85 02 03 00 00 48 83 c4
RSP: 0018:ffffc9000d067030 EFLAGS: 00000206
RAX: 0000000000000046 RBX: 0000000000000000 RCX: 0000000000000003
RDX: 0000000000000000 RSI: ffffffff8de5546a RDI: ffffffff8c1af420
RBP: ffffffff8e7e9220 R08: 000000002012fa30 R09: 0000000000000007
R10: 0000000000000200 R11: 0000000000000000 R12: 0000000000000002
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
rcu_lock_acquire include/linux/rcupdate.h:312 [inline]
rcu_read_lock include/linux/rcupdate.h:850 [inline]
class_rcu_constructor include/linux/rcupdate.h:1193 [inline]
unwind_next_frame+0xd1/0x1ea0 arch/x86/kernel/unwind_orc.c:495
arch_stack_walk+0x94/0xf0 arch/x86/kernel/stacktrace.c:25
stack_trace_save+0x8e/0xc0 kernel/stacktrace.c:122
save_stack+0x162/0x1e0 mm/page_owner.c:165
__set_page_owner+0x8c/0x540 mm/page_owner.c:341
set_page_owner include/linux/page_owner.h:32 [inline]
post_alloc_hook+0x153/0x170 mm/page_alloc.c:1889
prep_new_page mm/page_alloc.c:1897 [inline]
get_page_from_freelist+0x111d/0x3140 mm/page_alloc.c:3962
__alloc_frozen_pages_noprof+0x27c/0x2ba0 mm/page_alloc.c:5250
alloc_pages_mpol+0x1fb/0x550 mm/mempolicy.c:2484
folio_alloc_mpol_noprof+0x36/0x340 mm/mempolicy.c:2503
shmem_alloc_folio+0x135/0x160 mm/shmem.c:1930
shmem_alloc_and_add_folio+0x371/0xd40 mm/shmem.c:1972
shmem_get_folio_gfp+0x6ab/0x1900 mm/shmem.c:2567
shmem_get_folio mm/shmem.c:2673 [inline]
shmem_write_begin+0x1a4/0x420 mm/shmem.c:3327
generic_perform_write+0x292/0xa40 mm/filemap.c:4314
shmem_file_write_iter+0x10e/0x140 mm/shmem.c:3502
new_sync_write fs/read_write.c:595 [inline]
vfs_write+0x6ac/0x1070 fs/read_write.c:688
ksys_write+0x12a/0x250 fs/read_write.c:740
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x106/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fbf53f9c799
RSP: 002b:00007fbf54ef9028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007fbf54215fa0 RCX: 00007fbf53f9c799
RDX: 00000000fffffdf1 RSI: 0000000000000000 RDI: 0000000000000006
RBP: 00007fbf54032bd9 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fbf54216038 R14: 00007fbf54215fa0 R15: 00007ffe1bb3bb38
rcu: rcu_preempt kthread starved for 10456 jiffies! g25017 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->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:R running task stack:28824 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00080000
Call Trace:
context_switch kernel/sched/core.c:5295 [inline]
__schedule+0xfee/0x60e0 kernel/sched/core.c:6907
__schedule_loop kernel/sched/core.c:6989 [inline]
schedule+0xdd/0x390 kernel/sched/core.c:7004
schedule_timeout+0x127/0x280 kernel/time/sleep_timeout.c:99
rcu_gp_fqs_loop+0x1a9/0x900 kernel/rcu/tree.c:2095
rcu_gp_kthread+0x179/0x230 kernel/rcu/tree.c:2297
kthread+0x370/0x450 kernel/kthread.c:467
ret_from_fork+0x754/0xd80 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
rcu: Stack dump where RCU GP kthread last ran:
CPU: 1 UID: 0 PID: 5863 Comm: kworker/1:3 Tainted: G L syzkaller #0 PREEMPT(full)
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
Workqueue: events fqdir_free_fn
RIP: 0010:check_kcov_mode kernel/kcov.c:185 [inline]
RIP: 0010:write_comp_data+0x3a/0x90 kernel/kcov.c:246
Code: 65 48 8b 3d 70 4c 05 12 a9 00 01 ff 00 74 1b f6 c4 01 74 07 a9 00 00 ff 00 74 05 c3 cc cc cc cc 8b 87 54 16 00 00 85 c0 74 f1 <8b> 87 30 16 00 00 83 f8 03 75 e6 48 8b 87 38 16 00 00 8b bf 34 16
RSP: 0018:ffffc90004147a38 EFLAGS: 00000246
RAX: 0000000000000001 RBX: 0000000000000001 RCX: ffffffff81fbc26c
RDX: 0000000000000001 RSI: 0000000000000000 RDI: ffff88803872bc80
RBP: ffffc90004147b88 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000000 R12: 1ffff92000828f50
R13: 0000000000000001 R14: ffff8880b843c240 R15: ffff8880b843c388
FS: 0000000000000000(0000) GS:ffff88812444c000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f110280dff8 CR3: 000000007f162000 CR4: 00000000003526f0
Call Trace:
csd_lock_wait kernel/smp.c:342 [inline]
smp_call_function_single+0x20c/0x6a0 kernel/smp.c:687
rcu_barrier kernel/rcu/tree.c:3880 [inline]
rcu_barrier+0x2a4/0x6d0 kernel/rcu/tree.c:3817
fqdir_free_fn+0x32/0x140 net/ipv4/inet_fragment.c:166
process_one_work+0x9d7/0x1920 kernel/workqueue.c:3275
process_scheduled_works kernel/workqueue.c:3358 [inline]
worker_thread+0x5da/0xe40 kernel/workqueue.c:3439
kthread+0x370/0x450 kernel/kthread.c:467
ret_from_fork+0x754/0xd80 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245