INFO: rcu detected stall in sys_mkdir (3)

Status: upstream: reported on 2026/07/02 03:34
Reported-by: syzbot+4c1bee83865d88c91c75@syzkaller.appspotmail.com
First crash: 53d, last: 53d
▶ ▼ Similar bugs (17)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-5.15 INFO: rcu detected stall in sys_mkdir 1 1 604d 604d 0/3 auto-obsoleted due to no activity on 2025/04/06 10:37
linux-6.1 INFO: rcu detected stall in sys_mkdir 1 1 538d 538d 0/3 auto-obsoleted due to no activity on 2025/06/11 20:27
linux-6.1 INFO: rcu detected stall in sys_mkdir (2) origin:lts-only 1 syz, C inconclusive 2 61d 245d 0/3 upstream: reported C repro on 2025/12/22 06:04
upstream INFO: rcu detected stall in sys_mkdir (3) cgroups 1 1 2420d 2420d 0/29 closed as invalid on 2020/01/08 05:33
linux-5.15 INFO: rcu detected stall in sys_mkdir (3) 1 1 168d 168d 0/3 auto-obsoleted due to no activity on 2026/06/16 08:45
upstream INFO: rcu detected stall in sys_mkdir (7) ext4 1 1 1094d 1094d 0/29 auto-obsoleted due to no activity on 2023/10/24 07:40
linux-5.15 INFO: rcu detected stall in sys_mkdir (2) 1 1 338d 338d 0/3 auto-obsoleted due to no activity on 2025/12/28 08:27
linux-6.6 INFO: rcu detected stall in sys_mkdir 1 1 370d 370d 0/2 auto-obsoleted due to no activity on 2025/11/27 00:13
upstream INFO: rcu detected stall in sys_mkdir mm 1 2 2588d 2589d 0/29 auto-closed as invalid on 2019/10/25 14:21
upstream INFO: rcu detected stall in sys_mkdir (2) cgroups 1 5 2454d 2456d 0/29 closed as invalid on 2019/12/04 14:04
upstream INFO: rcu detected stall in sys_mkdir (6) ext4 1 2 1666d 1675d 0/29 closed as invalid on 2022/02/08 09:50
upstream INFO: rcu detected stall in sys_mkdir (4) mm 1 2 2419d 2419d 0/29 closed as invalid on 2020/01/09 08:13
upstream INFO: rcu detected stall in sys_mkdir (9) prio:high mm 1 syz done error 7 23d 576d 0/29 upstream: reported syz repro on 2025/01/25 04:35
upstream INFO: rcu detected stall in sys_mkdir (8) fs 1 1 693d 693d 0/29 auto-obsoleted due to no activity on 2024/12/28 09:04
upstream INFO: rcu detected stall in sys_mkdir (5) tomoyo 1 1 1802d 1802d 0/29 auto-closed as invalid on 2021/12/15 23:48
linux-6.6 INFO: rcu detected stall in sys_mkdir (2) 1 1 262d 262d 0/2 auto-obsoleted due to no activity on 2026/03/14 17:07
android-5-15 BUG: soft lockup in sys_mkdir 1 2 828d 833d 0/2 auto-obsoleted due to no activity on 2024/08/15 15:43

Sample crash report:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P5778/1:b..l P16703/1:b..l P16706/1:b..l
rcu: 	(detected by 1, t=10502 jiffies, g=101445, q=287 ncpus=2)
task:syz-executor    state:R  running task     stack:24712 pid:16706 ppid:5765   flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5381 [inline]
 __schedule+0x15ae/0x4660 kernel/sched/core.c:6700
 preempt_schedule_irq+0xbf/0x150 kernel/sched/core.c:7010
 irqentry_exit+0x67/0x70 kernel/entry/common.c:438
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:687
RIP: 0010:lock_acquire+0x208/0x420 kernel/locking/lockdep.c:5758
Code: f7 84 24 80 00 00 00 00 02 00 00 43 c6 44 3c 04 f8 0f 85 f0 00 00 00 41 f7 c6 00 02 00 00 74 01 fb 48 c7 44 24 60 0e 36 e0 45 <4b> c7 04 3c 00 00 00 00 43 c7 44 3c 08 00 00 00 00 65 48 8b 04 25
RSP: 0018:ffffc9000442f080 EFLAGS: 00000206
RAX: 0000000000000001 RBX: 0000000000000000 RCX: e432416fc2f90800
RDX: 0000000000000000 RSI: ffffffff8acadce0 RDI: ffffffff8b1c7be0
RBP: ffffc9000442f190 R08: dffffc0000000000 R09: 1ffffffff22378a0
R10: dffffc0000000000 R11: fffffbfff22378a1 R12: 1ffff92000885e1c
R13: ffffffff8d131da0 R14: 0000000000000246 R15: dffffc0000000000
 rcu_lock_acquire include/linux/rcupdate.h:334 [inline]
 rcu_read_lock include/linux/rcupdate.h:786 [inline]
 ext4_get_group_desc+0x12f/0x4d0 fs/ext4/balloc.c:286
 ext4_mb_prefetch_fini+0xa8/0x1d0 fs/ext4/mballoc.c:2814
 ext4_mb_regular_allocator+0x29b/0x36c0 fs/ext4/mballoc.c:3021
 ext4_mb_new_blocks+0xc9c/0x42f0 fs/ext4/mballoc.c:6254
 ext4_ext_map_blocks+0x1826/0x6890 fs/ext4/extents.c:4415
 ext4_map_blocks+0x9db/0x1a90 fs/ext4/inode.c:654
 ext4_getblk+0x1c9/0x720 fs/ext4/inode.c:864
 ext4_bread+0x2a/0x170 fs/ext4/inode.c:920
 ext4_append+0x2bf/0x560 fs/ext4/namei.c:83
 ext4_init_new_dir+0x2bc/0x550 fs/ext4/namei.c:3030
 ext4_mkdir+0x4c7/0xc90 fs/ext4/namei.c:3076
 vfs_mkdir+0x2a5/0x470 fs/namei.c:4121
 do_mkdirat+0x1dc/0x450 fs/namei.c:4144
 __do_sys_mkdir fs/namei.c:4164 [inline]
 __se_sys_mkdir fs/namei.c:4162 [inline]
 __x64_sys_mkdir+0x6e/0x80 fs/namei.c:4162
 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: 0033:0x7fc163dcb227
RSP: 002b:00007ffdccdb54d8 EFLAGS: 00000246 ORIG_RAX: 0000000000000053
RAX: ffffffffffffffda RBX: 00007ffdccdb5602 RCX: 00007fc163dcb227
RDX: 00000000072aadd0 RSI: 00000000000001c0 RDI: 00007ffdccdb55f0
RBP: 8421084210842109 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000072aadd0
R13: 00007ffdccdb5602 R14: 0000000000000004 R15: 00007fc163e5a040
 </TASK>
task:syz.0.2438      state:R  running task     stack:26056 pid:16703 ppid:16109  flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5381 [inline]
 __schedule+0x15ae/0x4660 kernel/sched/core.c:6700
 preempt_schedule_common+0x82/0xc0 kernel/sched/core.c:6867
 preempt_schedule+0xc0/0xd0 kernel/sched/core.c:6891
 preempt_schedule_thunk+0x1a/0x30 arch/x86/entry/thunk_64.S:45
 __raw_spin_unlock include/linux/spinlock_api_smp.h:143 [inline]
 _raw_spin_unlock+0x3a/0x40 kernel/locking/spinlock.c:186
 spin_unlock include/linux/spinlock.h:391 [inline]
 zap_pte_range mm/memory.c:1523 [inline]
 zap_pmd_range mm/memory.c:1571 [inline]
 zap_pud_range mm/memory.c:1600 [inline]
 zap_p4d_range mm/memory.c:1621 [inline]
 unmap_page_range+0x2577/0x32f0 mm/memory.c:1642
 unmap_vmas+0x286/0x3f0 mm/memory.c:1732
 exit_mmap+0x238/0xb90 mm/mmap.c:3302
 __mmput+0x118/0x3a0 kernel/fork.c:1357
 exit_mm+0x23f/0x340 kernel/exit.c:570
 do_exit+0x909/0x2530 kernel/exit.c:871
 do_group_exit+0x22d/0x2f0 kernel/exit.c:1026
 __do_sys_exit_group kernel/exit.c:1037 [inline]
 __se_sys_exit_group kernel/exit.c:1035 [inline]
 __x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1035
 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: 0033:0x7efc3af9de59
RSP: 002b:00007ffd08d446a8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007efc3af9de59
RDX: 0000000000000064 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007ffd08d4470c R08: 0000000000000000 R09: 00000000000927c0
R10: 00007efc3b226038 R11: 0000000000000246 R12: 000000000000000e
R13: 00000000000927c0 R14: 000000000013d36a R15: 00007ffd08d44760
 </TASK>
task:syz-executor    state:R  running task     stack:20560 pid:5778  ppid:1      flags:0x00004006
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5381 [inline]
 __schedule+0x15ae/0x4660 kernel/sched/core.c:6700
 preempt_schedule_irq+0xbf/0x150 kernel/sched/core.c:7010
 irqentry_exit+0x67/0x70 kernel/entry/common.c:438
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:687
RIP: 0010:lock_acquire+0x208/0x420 kernel/locking/lockdep.c:5758
Code: f7 84 24 80 00 00 00 00 02 00 00 43 c6 44 3c 04 f8 0f 85 f0 00 00 00 41 f7 c6 00 02 00 00 74 01 fb 48 c7 44 24 60 0e 36 e0 45 <4b> c7 04 3c 00 00 00 00 43 c7 44 3c 08 00 00 00 00 65 48 8b 04 25
RSP: 0018:ffffc900043af6a0 EFLAGS: 00000206
RAX: 0000000000000001 RBX: 0000000000000000 RCX: bc224cce933bac00
RDX: 0000000000000000 RSI: ffffffff8acadce0 RDI: ffffffff8b1c7be0
RBP: ffffc900043af7c0 R08: dffffc0000000000 R09: 1ffffffff22378a0
R10: dffffc0000000000 R11: fffffbfff22378a1 R12: 1ffff92000875ee0
R13: ffffffff8d131da0 R14: 0000000000000246 R15: dffffc0000000000
 rcu_lock_acquire include/linux/rcupdate.h:334 [inline]
 rcu_read_lock include/linux/rcupdate.h:786 [inline]
 page_ext_get+0x3e/0x2b0 mm/page_ext.c:508
 __reset_page_owner+0x2e/0x190 mm/page_owner.c:145
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1182 [inline]
 free_unref_page_prepare+0x7d7/0x8f0 mm/page_alloc.c:2366
 free_unref_page+0x32/0x2e0 mm/page_alloc.c:2459
 vfree+0x1a7/0x340 mm/vmalloc.c:2868
 kcov_put kernel/kcov.c:438 [inline]
 kcov_close+0x2b/0x50 kernel/kcov.c:534
 __fput+0x221/0x930 fs/file_table.c:384
 task_work_run+0x1d4/0x260 kernel/task_work.c:245
 exit_task_work include/linux/task_work.h:43 [inline]
 do_exit+0x986/0x2530 kernel/exit.c:884
 do_group_exit+0x22d/0x2f0 kernel/exit.c:1026
 get_signal+0x12a6/0x1390 kernel/signal.c:2903
 arch_do_signal_or_restart+0xc2/0x7b0 arch/x86/kernel/signal.c:310
 exit_to_user_mode_loop+0x70/0x110 kernel/entry/common.c:174
 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:210
 __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
 syscall_exit_to_user_mode+0x1a/0x50 kernel/entry/common.c:302
 do_syscall_64+0x61/0xb0 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fa6f315e68e
RSP: 002b:00007fff29338888 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
RAX: fffffffffffffe00 RBX: 000055555bbdd500 RCX: 00007fa6f315e68e
RDX: 0000000000000030 RSI: 00007fff29338980 RDI: 00000000000000f9
RBP: 00007fff2933892c R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000258
R13: 000000000000004d R14: 000000000013cbc6 R15: 00007fff29338980
 </TASK>
rcu: rcu_preempt kthread starved for 10603 jiffies! g101445 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:27152 pid:17    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5381 [inline]
 __schedule+0x15ae/0x4660 kernel/sched/core.c:6700
 schedule+0xbd/0x170 kernel/sched/core.c:6774
 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: 1 PID: 0 Comm: swapper/1 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
RIP: 0010:pv_native_safe_halt+0xf/0x10 arch/x86/kernel/paravirt.c:148
Code: dc 23 02 c3 cc cc cc cc cc cc cc f3 0f 1e fa 0f 0b 66 2e 0f 1f 84 00 00 00 00 00 f3 0f 1e fa 66 90 0f 00 2d 43 67 44 00 fb f4 <c3> 66 0f 1f 00 55 41 57 41 56 41 54 53 50 8b 2f eb 2c 89 cb 80 f9
RSP: 0018:ffffc90000187de0 EFLAGS: 000002c6
RAX: b177a4b0e7ab6000 RBX: ffffffff81628b01 RCX: b177a4b0e7ab6000
RDX: 0000000000000001 RSI: ffffffff8acacb60 RDI: ffffffff8b1c7be0
RBP: ffffc90000187f20 R08: ffff8880b8f36bab R09: 1ffff110171e6d75
R10: dffffc0000000000 R11: ffffed10171e6d76 R12: 1ffff92000030fc8
R13: dffffc0000000000 R14: 1ffff110036cd780 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b34722ff8 CR3: 0000000026dc5000 CR4: 00000000003506e0
Call Trace:
 <TASK>
 arch_safe_halt arch/x86/include/asm/paravirt.h:108 [inline]
 default_idle+0x13/0x20 arch/x86/kernel/process.c:753
 default_idle_call+0x6c/0xa0 kernel/sched/idle.c:97
 cpuidle_idle_call kernel/sched/idle.c:178 [inline]
 do_idle+0x221/0x5c0 kernel/sched/idle.c:302
 cpu_startup_entry+0x43/0x60 kernel/sched/idle.c:401
 start_secondary+0xee/0xf0 arch/x86/kernel/smpboot.c:323
 secondary_startup_64_no_verify+0x179/0x17b
 </TASK>

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/07/02 03:33 linux-6.6.y d1cfde2d5d15 27192279 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: rcu detected stall in sys_mkdir
* Struck through repros no longer work on HEAD.