INFO: rcu detected stall in sys_mount

Status: upstream: reported C repro on 2024/12/14 21:36
Bug presence: origin:lts-only
[Documentation on labels]
Reported-by: syzbot+4e7d075998b1d352e3bf@syzkaller.appspotmail.com
First crash: 607d, last: 50d
Fix bisection: the issue occurs on the latest tested release (bisect log)
Crash: INFO: rcu detected stall in corrupted (log)
Repro: C syz .config
  
▶ ▼ Bug presence (2)
Date Name Commit Repro Result
2025/05/12 linux-6.1.y (ToT) 02b72ccb5f9d C [report] INFO: rcu detected stall in corrupted
2025/05/12 upstream (ToT) 627277ba7c23 C Didn't crash
▶ ▼ Similar bugs (13)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.6 INFO: rcu detected stall in mount 1 1 14d 14d 0/2 upstream: reported on 2026/07/31 02:07
upstream INFO: rcu detected stall in sys_mount (8) prio:low overlayfs 1 syz, C error 43 3d11h 352d 0/29 upstream: reported C repro on 2025/08/27 13:07
upstream INFO: rcu detected stall in sys_mount (6) ntfs 1 syz, C inconclusive 82 1008d 1781d 0/29 auto-obsoleted due to no activity on 2024/02/18 04:52
upstream INFO: rcu detected stall in sys_mount (4) fs 1 2 2353d 2369d 0/29 auto-closed as invalid on 2020/06/02 15:48
upstream INFO: rcu detected stall in sys_mount (5) afs 1 syz, C done done 10 2143d 2165d 15/29 fixed on 2020/11/16 12:12
linux-5.15 INFO: rcu detected stall in sys_mount 1 2 609d 671d 0/3 auto-obsoleted due to no activity on 2025/03/22 20:11
upstream INFO: rcu detected stall in sys_mount (3) mm 1 6 2445d 2446d 0/29 closed as invalid on 2019/12/04 14:04
upstream INFO: rcu detected stall in sys_mount nfs 1 1 2851d 2851d 0/29 closed as invalid on 2018/10/29 13:47
upstream INFO: rcu detected stall in sys_mount (7) fs 1 syz, C inconclusive done 41 598d 840d 0/29 auto-obsoleted due to no activity on 2025/03/30 13:11
upstream INFO: rcu detected stall in sys_mount (2) exfat 1 1 2802d 2801d 0/29 closed as dup on 2018/12/12 21:01
linux-5.15 INFO: rcu detected stall in mount origin:lts-only 1 syz, C error 5 81d 465d 0/3 upstream: reported C repro on 2025/05/05 20:18
android-5-15 BUG: soft lockup in sys_mount origin:lts 1 syz, C error 17 770d 848d 0/2 auto-obsoleted due to no activity on 2024/10/17 05:03
upstream INFO: rcu detected stall in __se_sys_mount afs 1 syz, C done done 2 2106d 2229d 15/29 fixed on 2020/12/08 16:15
▶ ▼ Fix bisection attempts (2)
Created Duration User Patch Repo Result
2025/06/11 13:43 2h42m fix candidate upstream OK (0) job log
2025/06/04 11:56 2h50m bisect fix linux-6.1.y OK (0) job log log

Sample crash report:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P4260/1:b..l
	(detected by 1, t=10503 jiffies, g=8785, q=76 ncpus=2)
task:syz-executor236 state:R  running task     stack:25920 pid:4260  ppid:4255   flags:0x00004002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5244 [inline]
 __schedule+0x10e9/0x40d0 kernel/sched/core.c:6561
 preempt_schedule_irq+0xb1/0x150 kernel/sched/core.c:6873
 irqentry_exit+0x63/0x70 kernel/entry/common.c:439
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691
RIP: 0010:lock_acquire+0x20f/0x490 kernel/locking/lockdep.c:5666
Code: 00 9c 8f 84 24 80 00 00 00 f6 84 24 81 00 00 00 02 0f 85 f5 00 00 00 41 f7 c6 00 02 00 00 74 01 fb 48 c7 44 24 60 0e 36 e0 45 <4b> c7 44 3d 00 00 00 00 00 66 43 c7 44 3d 09 00 00 43 c6 44 3d 0b
RSP: 0018:ffffc90003d67480 EFLAGS: 00000206
RAX: 0000000000000001 RBX: 0000000000000000 RCX: 75c24ad516f25b00
RDX: 0000000000000000 RSI: ffffffff8a6c0f80 RDI: ffffffff8abf0da0
RBP: ffffc90003d67598 R08: dffffc0000000000 R09: fffffbfff2117049
R10: fffffbfff2117049 R11: 1ffffffff2117048 R12: 0000000000000001
R13: 1ffff920007ace9c R14: 0000000000000246 R15: dffffc0000000000
 rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
 rcu_read_lock include/linux/rcupdate.h:791 [inline]
 is_bpf_text_address+0x43/0x2a0 kernel/bpf/core.c:735
 kernel_text_address+0x9c/0xd0 kernel/extable.c:125
 __kernel_text_address+0x9/0x30 kernel/extable.c:79
 unwind_get_return_address+0x49/0x80 arch/x86/kernel/unwind_orc.c:323
 arch_stack_walk+0xf2/0x140 arch/x86/kernel/stacktrace.c:26
 stack_trace_save+0x98/0xe0 kernel/stacktrace.c:122
 kasan_save_stack mm/kasan/common.c:45 [inline]
 kasan_set_track+0x4b/0x70 mm/kasan/common.c:52
 kasan_save_free_info+0x2d/0x50 mm/kasan/generic.c:516
 ____kasan_slab_free+0x126/0x1e0 mm/kasan/common.c:236
 kasan_slab_free include/linux/kasan.h:177 [inline]
 slab_free_hook mm/slub.c:1724 [inline]
 slab_free_freelist_hook+0x131/0x1a0 mm/slub.c:1750
 slab_free mm/slub.c:3661 [inline]
 kmem_cache_free+0xf7/0x290 mm/slub.c:3683
 kern_path+0x3b/0x50 fs/namei.c:2608
 tomoyo_mount_acl security/tomoyo/mount.c:136 [inline]
 tomoyo_mount_permission+0x75f/0x940 security/tomoyo/mount.c:237
 security_sb_mount+0x83/0xb0 security/security.c:993
 path_mount+0xb8/0x1010 fs/namespace.c:3329
 do_mount fs/namespace.c:3400 [inline]
 __do_sys_mount fs/namespace.c:3608 [inline]
 __se_sys_mount+0x2d6/0x3c0 fs/namespace.c:3585
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fe9408efcea
RSP: 002b:00007fff699bc1f8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007fe9409460ae RCX: 00007fe9408efcea
RDX: 0000000000000000 RSI: 00007fe940946181 RDI: 00007fe940946192
RBP: 00007fe940946181 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000045001 R11: 0000000000000246 R12: 00007fe94094c33c
R13: 00007fe940946106 R14: 0000000000000001 R15: 0000000000000001
 </TASK>
rcu: rcu_preempt kthread starved for 10557 jiffies! g8785 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:27840 pid:16    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5244 [inline]
 __schedule+0x10e9/0x40d0 kernel/sched/core.c:6561
 schedule+0xb9/0x180 kernel/sched/core.c:6637
 schedule_timeout+0x15c/0x280 kernel/time/timer.c:1965
 rcu_gp_fqs_loop+0x2f2/0x1310 kernel/rcu/tree.c:1706
 rcu_gp_kthread+0x95/0x380 kernel/rcu/tree.c:1905
 kthread+0x29d/0x330 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </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 PID: 4280 Comm: syz-executor236 Not tainted 6.1.136-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/19/2025
RIP: 0010:check_kcov_mode kernel/kcov.c:182 [inline]
RIP: 0010:__sanitizer_cov_trace_pc+0x13/0x60 kernel/kcov.c:216
Code: 48 8b 3d 80 c0 7d 0c 48 89 de 5b e9 17 aa 50 00 00 00 cc cc 00 00 cc 48 8b 04 24 65 48 8b 0d 94 ab 81 7e 65 8b 15 95 ab 81 7e <81> e2 00 01 ff 00 74 11 81 fa 00 01 00 00 75 35 83 b9 1c 16 00 00
RSP: 0018:ffffc90003e27ac8 EFLAGS: 00000046
RAX: ffffffff814ffb08 RBX: ffff88803022bb80 RCX: ffff88803022bb80
RDX: 0000000080000001 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: dffffc0000000000 R09: ffffed1006045771
R10: ffffed1006045771 R11: 1ffff11006045770 R12: dffffc0000000000
R13: 0000000000000000 R14: ffff88803022c0f0 R15: ffff88802969a908
FS:  0000555591a693c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fe940945448 CR3: 00000000790e4000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 arch_static_branch arch/x86/include/asm/jump_label.h:27 [inline]
 freezing include/linux/freezer.h:36 [inline]
 recalc_sigpending+0x158/0x1c0 kernel/signal.c:184
 __set_task_blocked kernel/signal.c:3031 [inline]
 __set_current_blocked+0x1f8/0x240 kernel/signal.c:3059
 set_current_blocked kernel/signal.c:3044 [inline]
 signal_delivered kernel/signal.c:2907 [inline]
 signal_setup_done+0x28c/0x440 kernel/signal.c:2919
 handle_signal arch/x86/kernel/signal.c:846 [inline]
 arch_do_signal_or_restart+0xeba/0x1230 arch/x86/kernel/signal.c:873
 exit_to_user_mode_loop+0x70/0x110 kernel/entry/common.c:174
 exit_to_user_mode_prepare+0xb1/0x140 kernel/entry/common.c:210
 __syscall_exit_to_user_mode_work kernel/entry/common.c:292 [inline]
 syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:303
 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:87
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fe940914d90
Code: 83 c0 16 83 e0 f7 74 12 50 48 8d 3d 1a 2a 03 00 e8 d5 06 fb ff 0f 1f 44 00 00 c3 66 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 <83> ff 21 74 0b c3 66 2e 0f 1f 84 00 00 00 00 00 55 53 48 89 f3 48
RSP: 002b:00007fff699bba38 EFLAGS: 00000202
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000004
RDX: 00007fff699bba40 RSI: 00007fff699bbb70 RDI: 0000000000000021
RBP: 00007fe940977130 R08: 00007fe9408ae990 R09: 00007fe9408ae990
R10: 0000000000000000 R11: 0000000000000293 R12: 00007fe940979dc8
R13: 0000000000000000 R14: 00007fe940979de0 R15: 00007fe9408b9f80
 </TASK>
sched: RT throttling activated

Crashes (8):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/05/04 16:53 linux-6.1.y b6736e03756f b0714e37 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in mount
2025/03/12 21:28 linux-6.1.y 6ae7ac5c4251 1a5d9317 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in sys_mount
2025/01/07 07:16 linux-6.1.y 7dc732d24ff7 f3558dbf .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in sys_mount
2024/12/14 21:35 linux-6.1.y 52f863f820fd 7cbfbb3a .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in sys_mount
2026/06/24 21:52 linux-6.1.y fdb6fcb41cc7 302586aa .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in mount
2026/01/07 22:59 linux-6.1.y 50cbba13faa2 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in mount
2025/10/05 13:58 linux-6.1.y 882efbdd9d34 49379ee0 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in mount
2025/06/14 01:10 linux-6.1.y 58485ff1a74f 0e8da31f .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in mount
* Struck through repros no longer work on HEAD.