syzbot


INFO: rcu detected stall in __do_munmap

Status: upstream: reported on 2025/10/02 20:10
Reported-by: syzbot+7b9d468fb2e9a6d786ce@syzkaller.appspotmail.com
First crash: 15d, last: 15d
Similar bugs (1)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: rcu detected stall in __do_munmap kasan mm 1 1 1443d 1443d 0/29 auto-closed as invalid on 2022/02/02 22:05

Sample crash report:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P21318/1:b..l
	(detected by 0, t=10502 jiffies, g=82313, q=168)
task:sed             state:R  running task     stack:27360 pid:21318 ppid: 21316 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5049 [inline]
 __schedule+0x11bb/0x4390 kernel/sched/core.c:6395
 preempt_schedule_irq+0xb1/0x150 kernel/sched/core.c:6799
 irqentry_exit+0x63/0x70 kernel/entry/common.c:432
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:lockdep_enabled kernel/locking/lockdep.c:91 [inline]
RIP: 0010:lock_is_held_type+0x45/0x190 kernel/locking/lockdep.c:5659
Code: 08 bd ff ff ff ff 83 3d 2c 98 c0 03 00 0f 84 03 01 00 00 65 8b 05 1b 48 59 76 85 c0 0f 85 f4 00 00 00 65 48 8b 1d 8b 3e 59 76 <83> bb ec 0a 00 00 00 0f 85 df 00 00 00 41 89 f7 49 89 fe 48 c7 04
RSP: 0018:ffffc9000156f9c0 EFLAGS: 00000246
RAX: 0000000000000000 RBX: ffff888068a69dc0 RCX: 63c559a98c487d00
RDX: 0000000000000000 RSI: 00000000ffffffff RDI: ffffffff8c141f08
RBP: 00000000ffffffff R08: dffffc0000000000 R09: fffffbfff1ff7a19
R10: fffffbfff1ff7a19 R11: 1ffffffff1ff7a18 R12: ffff88805cd35e70
R13: dffffc0000000000 R14: ffff888068a69dc0 R15: dffffc0000000000
 lock_is_held include/linux/lockdep.h:287 [inline]
 task_css include/linux/cgroup.h:496 [inline]
 mem_cgroup_from_task+0x5e/0x110 mm/memcontrol.c:935
 get_obj_cgroup_from_current+0x146/0x2f0 mm/memcontrol.c:2926
 memcg_slab_pre_alloc_hook mm/slab.h:283 [inline]
 slab_pre_alloc_hook+0x7e/0xc0 mm/slab.h:497
 slab_alloc_node mm/slub.c:3139 [inline]
 slab_alloc mm/slub.c:3233 [inline]
 kmem_cache_alloc+0x3d/0x290 mm/slub.c:3238
 vm_area_dup+0x1e/0xb0 kernel/fork.c:358
 __split_vma+0xb1/0x410 mm/mmap.c:2730
 __do_munmap+0x3eb/0xdc0 mm/mmap.c:2865
 do_munmap mm/mmap.c:2910 [inline]
 munmap_vma_range mm/mmap.c:603 [inline]
 __mmap_region mm/mmap.c:1757 [inline]
 mmap_region+0x8bb/0x1660 mm/mmap.c:2933
 do_mmap+0x81f/0xea0 mm/mmap.c:1586
 vm_mmap_pgoff+0x1b2/0x2b0 mm/util.c:551
 ksys_mmap_pgoff+0x542/0x780 mm/mmap.c:1635
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f0b7e095242
RSP: 002b:00007ffd00858828 EFLAGS: 00000206 ORIG_RAX: 0000000000000009
RAX: ffffffffffffffda RBX: 00007f0b7ddb1000 RCX: 00007f0b7e095242
RDX: 0000000000000001 RSI: 0000000000002000 RDI: 00007f0b7ddb1000
RBP: 0000000000000812 R08: 0000000000000003 R09: 000000000000b000
R10: 0000000000000812 R11: 0000000000000206 R12: 00007ffd008588b0
R13: 00007f0b7e072580 R14: 00007ffd00858ca0 R15: 00000fffa010b108
 </TASK>
rcu: rcu_preempt kthread starved for 10523 jiffies! g82313 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:28128 pid:   15 ppid:     2 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5049 [inline]
 __schedule+0x11bb/0x4390 kernel/sched/core.c:6395
 schedule+0x11b/0x1e0 kernel/sched/core.c:6478
 schedule_timeout+0x15c/0x280 kernel/time/timer.c:1914
 rcu_gp_fqs_loop+0x29e/0x11b0 kernel/rcu/tree.c:1972
 rcu_gp_kthread+0x98/0x350 kernel/rcu/tree.c:2145
 kthread+0x436/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 21318 Comm: sed Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
RIP: 0010:deref_stack_reg+0x0/0x120 arch/x86/kernel/unwind_orc.c:356
Code: 9c 87 00 e9 98 f7 ff ff 44 89 f1 80 e1 07 38 c1 0f 8c e6 f4 ff ff 4c 89 f7 e8 4c 9c 87 00 e9 d9 f4 ff ff 0f 1f 80 00 00 00 00 <55> 41 57 41 56 41 55 41 54 53 48 89 d3 49 89 f6 49 89 ff 49 bc 00
RSP: 0018:ffffc9000156f5e0 EFLAGS: 00000287
RAX: fffffffffffffff0 RBX: ffffc9000156f6a8 RCX: 0000000000000000
RDX: ffffc9000156f6e8 RSI: ffffc9000156fc90 RDI: ffffc9000156f6a8
RBP: ffffc9000156f6f0 R08: dffffc0000000000 R09: ffffc9000156f6f8
R10: fffff520002adee1 R11: 1ffff920002adedf R12: 1ffffffff1bc78ff
R13: dffffc0000000000 R14: ffffc9000156f6f8 R15: ffffffff8de3c7fc
FS:  0000000000000000(0000) GS:ffff8880b9100000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ff2a9c0cff8 CR3: 0000000079e22000 CR4: 00000000003506e0
Call Trace:
 <TASK>
 unwind_next_frame+0x115d/0x1d90 arch/x86/kernel/unwind_orc.c:-1
 arch_stack_walk+0x10c/0x140 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0x98/0xe0 kernel/stacktrace.c:122
 kasan_save_stack mm/kasan/common.c:38 [inline]
 kasan_set_track+0x4b/0x70 mm/kasan/common.c:46
 kasan_set_free_info+0x1f/0x40 mm/kasan/generic.c:360
 ____kasan_slab_free+0xd5/0x110 mm/kasan/common.c:366
 kasan_slab_free include/linux/kasan.h:230 [inline]
 slab_free_hook mm/slub.c:1710 [inline]
 slab_free_freelist_hook+0xea/0x170 mm/slub.c:1736
 slab_free mm/slub.c:3504 [inline]
 kmem_cache_free+0x8f/0x210 mm/slub.c:3520
 remove_vma mm/mmap.c:188 [inline]
 exit_mmap+0x4d8/0x5f0 mm/mmap.c:3227
 __mmput+0x115/0x3b0 kernel/fork.c:1127
 exit_mm+0x567/0x6c0 kernel/exit.c:550
 do_exit+0x5a1/0x20a0 kernel/exit.c:870
 do_group_exit+0x12e/0x300 kernel/exit.c:997
 __do_sys_exit_group kernel/exit.c:1008 [inline]
 __se_sys_exit_group kernel/exit.c:1006 [inline]
 __x64_sys_exit_group+0x3b/0x40 kernel/exit.c:1006
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f0b7dea06c5
Code: Unable to access opcode bytes at RIP 0x7f0b7dea069b.
RSP: 002b:00007ffd00859968 EFLAGS: 00000202 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 00007f0b7dfa1fe8 RCX: 00007f0b7dea06c5
RDX: 00000000000000e7 RSI: ffffffffffffff88 RDI: 0000000000000000
RBP: 0000000000000001 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f0b7dfa0680 R15: 00007f0b7dfa2000
 </TASK>

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/10/02 20:10 linux-5.15.y 29e53a5b1c4f 49379ee0 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in __do_munmap
* Struck through repros no longer work on HEAD.