syzbot


INFO: rcu detected stall in memfd_check_seals_mmap

Status: auto-obsoleted due to no activity on 2025/11/17 17:41
Subsystems: mm
[Documentation on labels]
First crash: 150d, last: 150d

Sample crash report:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	1-...!: (0 ticks this GP) idle=1624/1/0x4000000000000000 softirq=158731/158731 fqs=0
rcu: 	(detected by 0, t=10502 jiffies, g=130225, q=407 ncpus=2)
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 32558 Comm: syz.8.5152 Not tainted 6.17.0-rc2-syzkaller-00028-gbe48bcf004f9 #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
RIP: 0010:preempt_count arch/x86/include/asm/preempt.h:27 [inline]
RIP: 0010:check_kcov_mode kernel/kcov.c:183 [inline]
RIP: 0010:write_comp_data+0x11/0x90 kernel/kcov.c:246
Code: db 09 0f 1f 80 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 49 89 d2 49 89 f8 49 89 f1 65 48 8b 15 a7 b4 1a 12 <65> 8b 05 b8 b4 1a 12 a9 00 01 ff 00 74 1d f6 c4 01 74 67 a9 00 00
RSP: 0018:ffffc90000a08e20 EFLAGS: 00000046
RAX: 0000000000010001 RBX: 0000000000000001 RCX: ffffffff81a83eb9
RDX: ffff88803b5d8000 RSI: 0000000000000007 RDI: 0000000000000005
RBP: 0000000000000000 R08: 0000000000000005 R09: 0000000000000007
R10: 0000000000000001 R11: ffffffff9b0140f8 R12: ffff8880b8527c80
R13: 187457cb70000000 R14: ffff888034bbd340 R15: 0000000000000001
FS:  00007fbdbddf66c0(0000) GS:ffff8881247bc000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fbdbddf5f98 CR3: 0000000060c37000 CR4: 00000000003526f0
Call Trace:
 <IRQ>
 cpu_max_bits_warn include/linux/cpumask.h:135 [inline]
 cpumask_check include/linux/cpumask.h:142 [inline]
 cpumask_test_cpu include/linux/cpumask.h:646 [inline]
 cpu_online include/linux/cpumask.h:1205 [inline]
 trace_hrtimer_cancel+0x29/0x200 include/trace/events/timer.h:317
 debug_deactivate kernel/time/hrtimer.c:491 [inline]
 __run_hrtimer kernel/time/hrtimer.c:1729 [inline]
 __hrtimer_run_queues+0x477/0xad0 kernel/time/hrtimer.c:1825
 hrtimer_interrupt+0x397/0x8e0 kernel/time/hrtimer.c:1887
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1039 [inline]
 __sysvec_apic_timer_interrupt+0x10b/0x3f0 arch/x86/kernel/apic/apic.c:1056
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1050 [inline]
 sysvec_apic_timer_interrupt+0x9f/0xc0 arch/x86/kernel/apic/apic.c:1050
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
RIP: 0010:__sanitizer_cov_trace_pc+0x41/0x70 kernel/kcov.c:217
Code: a9 00 01 ff 00 74 1d f6 c4 01 74 43 a9 00 00 0f 00 75 3c a9 00 00 f0 00 75 35 8b 82 3c 16 00 00 85 c0 74 2b 8b 82 18 16 00 00 <83> f8 02 75 20 48 8b 8a 20 16 00 00 8b 92 1c 16 00 00 48 8b 01 48
RSP: 0018:ffffc9001435fc68 EFLAGS: 00000246
RAX: 0000000000000000 RBX: ffff8880736e0700 RCX: ffffffff820aff22
RDX: ffff88803b5d8000 RSI: ffffffff8231d0d1 RDI: ffff8880736e0700
RBP: ffffc9001435fcf8 R08: 0000000000000007 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000005 R12: 0000200000000000
R13: 0000000000000000 R14: ffffffff81fcfd40 R15: ffff888036818e90
 shmem_file include/linux/shmem_fs.h:178 [inline]
 memfd_file_seals_ptr mm/memfd.c:186 [inline]
 memfd_check_seals_mmap+0x21/0x250 mm/memfd.c:374
 do_mmap+0xf7f/0x1210 mm/mmap.c:489
 vm_mmap_pgoff+0x29e/0x470 mm/util.c:580
 ksys_mmap_pgoff+0x32c/0x5c0 mm/mmap.c:604
 __do_sys_mmap arch/x86/kernel/sys_x86_64.c:89 [inline]
 __se_sys_mmap arch/x86/kernel/sys_x86_64.c:82 [inline]
 __x64_sys_mmap+0x125/0x190 arch/x86/kernel/sys_x86_64.c:82
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0x4c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fbdbfb8ebe9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fbdbddf6038 EFLAGS: 00000246 ORIG_RAX: 0000000000000009
RAX: ffffffffffffffda RBX: 00007fbdbfdb6090 RCX: 00007fbdbfb8ebe9
RDX: 0000000000000009 RSI: 0000000000003000 RDI: 0000200000000000
RBP: 00007fbdbfc11e19 R08: 0000000000000003 R09: 0000000000000000
R10: 0000000000000012 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fbdbfdb6128 R14: 00007fbdbfdb6090 R15: 00007ffd67b2d3b8
 </TASK>
rcu: rcu_preempt kthread timer wakeup didn't happen for 10501 jiffies! g130225 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402
rcu: 	Possible timer handling issue on cpu=1 timer-softirq=70470
rcu: rcu_preempt kthread starved for 10502 jiffies! g130225 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->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:I stack:28144 pid:16    tgid:16    ppid:2      task_flags:0x208040 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5357 [inline]
 __schedule+0x1190/0x5de0 kernel/sched/core.c:6961
 __schedule_loop kernel/sched/core.c:7043 [inline]
 schedule+0xe7/0x3a0 kernel/sched/core.c:7058
 schedule_timeout+0x123/0x290 kernel/time/sleep_timeout.c:99
 rcu_gp_fqs_loop+0x1ea/0xb00 kernel/rcu/tree.c:2083
 rcu_gp_kthread+0x270/0x380 kernel/rcu/tree.c:2285
 kthread+0x3c5/0x780 kernel/kthread.c:463
 ret_from_fork+0x5d7/0x6f0 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/08/19 17:31 upstream be48bcf004f9 523f460e .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root INFO: rcu detected stall in memfd_check_seals_mmap
* Struck through repros no longer work on HEAD.