INFO: rcu detected stall in sys_fallocate (6)

Status: auto-obsoleted due to no activity on 2026/08/02 11:16
Subsystems: mm
Labels: prio:high
[Documentation on labels]
First crash: 146d, last: 98d
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ID Workflow Result Correct Bug Created Started Finished Revision
db9605a0 assessment-security DenialOfService: ✅ Exploitable: ✅ FilesystemTrigger: ❌ NetworkTrigger: ❌ PeripheralTrigger: ❌ RemoteTrigger: ❌ Unprivileged: ✅ UserNamespace: ✅ VMGuestTrigger: ❌ VMHostTrigger: ❌ ❓ INFO: rcu detected stall in sys_fallocate (6) 2026/05/17 17:27 2026/05/17 17:27 2026/05/17 18:13 de5aae85
▶ ▼ Similar bugs (5)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: rcu detected stall in sys_fallocate (2) ext4 1 1 1445d 1445d 0/29 auto-obsoleted due to no activity on 2022/11/24 05:24
upstream INFO: rcu detected stall in sys_fallocate (4) mm 1 1 686d 686d 0/29 auto-obsoleted due to no activity on 2024/12/22 03:36
upstream INFO: rcu detected stall in sys_fallocate (5) mm 1 1 411d 411d 0/29 auto-obsoleted due to no activity on 2025/09/23 13:27
upstream INFO: rcu detected stall in sys_fallocate (3) mm 1 4 780d 794d 0/29 auto-obsoleted due to no activity on 2024/09/18 18:49
upstream INFO: rcu detected stall in sys_fallocate ext4 1 1 1677d 1677d 0/29 closed as invalid on 2022/02/08 09:50

Sample crash report:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P5633/1:b..l
rcu: 	(detected by 1, t=10504 jiffies, g=74233, q=1131 ncpus=2)
task:syz-executor    state:R  running task     stack:22488 pid:5633  tgid:5633  ppid:5619   task_flags:0x400140 flags:0x00080000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5388 [inline]
 __schedule+0x17b4/0x5680 kernel/sched/core.c:7189
 preempt_schedule_irq+0x4d/0xa0 kernel/sched/core.c:7513
 irqentry_exit_to_kernel_mode include/linux/irq-entry-common.h:547 [inline]
 irqentry_exit+0x14f/0x730 kernel/entry/common.c:164
 asm_sysvec_reschedule_ipi+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
RIP: 0010:lock_is_held_type+0x106/0x150 kernel/locking/lockdep.c:5945
Code: 19 00 00 b8 ff ff ff ff 65 0f c1 05 74 fd 90 07 83 f8 01 75 25 9c 58 a9 00 02 00 00 75 39 41 f7 c4 00 02 00 00 74 01 fb 89 d8 <5b> 41 5c 41 5d 41 5e 41 5f 5d e9 a6 f8 67 f5 cc 90 0f 0b 90 48 c7
RSP: 0018:ffffc90003287490 EFLAGS: 00000206
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000046
RDX: ffff8880355bdc40 RSI: ffffffff8e2189dd RDI: ffffffff8c28ac60
RBP: 00000000ffffffff R08: ffffea00021a5877 R09: 1ffffd4000434b0e
R10: dffffc0000000000 R11: fffff94000434b0f R12: 0000000000000246
R13: ffff8880355bdc40 R14: ffff888077812db0 R15: 0000000000000001
 lock_is_held include/linux/lockdep.h:249 [inline]
 xa_entry include/linux/xarray.h:1226 [inline]
 xas_reload+0xfc/0x470 include/linux/xarray.h:1624
 find_get_entry mm/filemap.c:2085 [inline]
 find_lock_entries+0x39f/0xb20 mm/filemap.c:2172
 shmem_undo_range+0x2d6/0x1660 mm/shmem.c:1131
 shmem_truncate_range mm/shmem.c:1277 [inline]
 shmem_evict_inode+0x289/0xae0 mm/shmem.c:1407
 evict+0x61e/0xb10 fs/inode.c:841
 __dentry_kill+0x1a2/0x690 fs/dcache.c:718
 finish_dput+0xc9/0x480 fs/dcache.c:927
 __fput+0x691/0xa60 fs/file_table.c:518
 task_work_run+0x1d9/0x270 kernel/task_work.c:233
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 __exit_to_user_mode_loop kernel/entry/common.c:67 [inline]
 exit_to_user_mode_loop+0xed/0x480 kernel/entry/common.c:98
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline]
 syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:238 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:318 [inline]
 do_syscall_64+0x33e/0xf80 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fb6e035d60e
RSP: 002b:00007ffc7137b818 EFLAGS: 00000246 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 000055558f3e3500 RCX: 00007fb6e035d60e
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000003
RBP: 00007ffc7137b8bc R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000000001be
R13: 00000000000927c0 R14: 0000000000124e00 R15: 00007ffc7137b910
 </TASK>
rcu: rcu_preempt kthread timer wakeup didn't happen for 10503 jiffies! g74233 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402
rcu: 	Possible timer handling issue on cpu=0 timer-softirq=49599
rcu: rcu_preempt kthread starved for 10504 jiffies! g74233 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->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:I stack:27248 pid:16    tgid:16    ppid:2      task_flags:0x208040 flags:0x00080000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5388 [inline]
 __schedule+0x17b4/0x5680 kernel/sched/core.c:7189
 __schedule_loop kernel/sched/core.c:7268 [inline]
 schedule+0x164/0x360 kernel/sched/core.c:7283
 schedule_timeout+0x158/0x2c0 kernel/time/sleep_timeout.c:99
 rcu_gp_fqs_loop+0x312/0x11d0 kernel/rcu/tree.c:2095
 rcu_gp_kthread+0x9e/0x2b0 kernel/rcu/tree.c:2297
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 14459 Comm: syz.6.1485 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
RIP: 0010:trace_lock_release include/trace/events/lock.h:69 [inline]
RIP: 0010:lock_release+0x2a/0x3c0 kernel/locking/lockdep.c:5879
Code: f3 0f 1e fa 55 41 57 41 56 41 55 41 54 53 48 83 ec 30 49 89 f5 49 89 fe 65 48 8b 05 20 21 97 11 48 89 44 24 28 0f 1f 44 00 00 <65> 8b 05 23 21 97 11 83 f8 08 0f 83 56 02 00 00 89 c0 48 0f a3 05
RSP: 0018:ffffc90000007d58 EFLAGS: 00000082
RAX: 5615e9a7f8c31400 RBX: 0000000000000046 RCX: ffff8880780adc40
RDX: 0000000000010000 RSI: ffffffff81b28483 RDI: ffff8880b8628298
RBP: ffff88802a05e300 R08: ffff88802a05e327 R09: ffff88802a05e318
R10: dffffc0000000000 R11: ffffed100540bc65 R12: ffff8880b8628280
R13: ffffffff81b28483 R14: ffff8880b8628298 R15: ffffffff89b83e90
FS:  00007fb6a87ee6c0(0000) GS:ffff888125290000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000110c3358a5 CR3: 000000005d5ef000 CR4: 0000000000350ef0
Call Trace:
 <IRQ>
 __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:176 [inline]
 _raw_spin_unlock_irqrestore+0x1b/0x80 kernel/locking/spinlock.c:198
 __run_hrtimer kernel/time/hrtimer.c:1926 [inline]
 __hrtimer_run_queues+0x2c3/0xa20 kernel/time/hrtimer.c:1994
 hrtimer_interrupt+0x44b/0x950 kernel/time/hrtimer.c:2113
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1050 [inline]
 __sysvec_apic_timer_interrupt+0x102/0x430 arch/x86/kernel/apic/apic.c:1067
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1061 [inline]
 sysvec_apic_timer_interrupt+0xa1/0xc0 arch/x86/kernel/apic/apic.c:1061
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:deref_stack_reg+0x1b3/0x230 arch/x86/kernel/unwind_orc.c:422
Code: 39 f0 0f 96 c0 20 c8 3c 01 75 30 4c 89 c7 49 89 f7 e8 11 08 00 00 49 89 c6 48 8b 5c 24 18 48 89 d8 48 c1 e8 03 42 80 3c 38 00 <74> 08 48 89 df e8 43 dd b9 00 4c 89 33 b0 01 eb 02 31 c0 48 83 c4
RSP: 0018:ffffc90003fff180 EFLAGS: 00000246
RAX: 1ffff920007ffe5d RBX: ffffc90003fff2e8 RCX: 0000000000000001
RDX: ffffc90003fff2e8 RSI: dffffc0000000000 RDI: ffffc90003fff5d0
RBP: 1ffff920007ffe55 R08: ffffc90003fff5d0 R09: ffffc90003fff2f8
R10: dffffc0000000000 R11: fffff520007ffe61 R12: 1ffff920007ffe56
R13: 1ffff920007ffe57 R14: 1ffffffff1c4b7e2 R15: dffffc0000000000
 unwind_next_frame+0x19d5/0x2550 arch/x86/kernel/unwind_orc.c:-1
 arch_stack_walk+0x11b/0x150 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0xa9/0x100 kernel/stacktrace.c:122
 save_stack+0x122/0x230 mm/page_owner.c:165
 __set_page_owner+0x8d/0x4c0 mm/page_owner.c:341
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x231/0x280 mm/page_alloc.c:1858
 prep_new_page mm/page_alloc.c:1866 [inline]
 get_page_from_freelist+0x24ba/0x2540 mm/page_alloc.c:3946
 __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5226
 alloc_pages_mpol+0x235/0x490 mm/mempolicy.c:2490
 folio_alloc_mpol_noprof+0x39/0x160 mm/mempolicy.c:2509
 shmem_alloc_folio mm/shmem.c:1933 [inline]
 shmem_alloc_and_add_folio+0x442/0xf80 mm/shmem.c:1975
 shmem_get_folio_gfp+0x5a9/0x1670 mm/shmem.c:2564
 shmem_get_folio mm/shmem.c:2670 [inline]
 shmem_fallocate+0x96f/0xec0 mm/shmem.c:3766
 vfs_fallocate+0x669/0x7e0 fs/open.c:338
 ksys_fallocate fs/open.c:362 [inline]
 __do_sys_fallocate fs/open.c:367 [inline]
 __se_sys_fallocate fs/open.c:365 [inline]
 __x64_sys_fallocate+0xc0/0x110 fs/open.c:365
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fb6aa59cdd9
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:00007fb6a87ee028 EFLAGS: 00000246 ORIG_RAX: 000000000000011d
RAX: ffffffffffffffda RBX: 00007fb6aa815fa0 RCX: 00007fb6aa59cdd9
RDX: 0000000000fea000 RSI: 0000000000000000 RDI: 0000000000000004
RBP: 00007fb6aa632d69 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000002000402 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fb6aa816038 R14: 00007fb6aa815fa0 R15: 00007ffcba7dcd08
 </TASK>

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/05/04 11:11 upstream 6d35786de281 85f1bcf2 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root INFO: rcu detected stall in sys_fallocate
2026/03/16 14:56 upstream f338e7738378 64e21424 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto INFO: rcu detected stall in sys_fallocate
* Struck through repros no longer work on HEAD.