[v5.15] INFO: rcu detected stall in __do_munmap

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 29e53a5b1c4f Linux 5.15.194
git tree: linux-5.15.y
console output: https://syzkaller.appspot.com/x/log.txt?x=1778cee2580000
kernel config: https://syzkaller.appspot.com/x/.config?x=e1bb6d24ef2164eb
dashboard link: https://syzkaller.appspot.com/bug?extid=7b9d468fb2e9a6d786ce
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/0eeaf49a514b/disk-29e53a5b.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/0d94b4e7dfb6/vmlinux-29e53a5b.xz
kernel image: https://storage.googleapis.com/syzbot-assets/807fd9b16ada/bzImage-29e53a5b.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+7b9d46...@syzkaller.appspotmail.com

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>


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title

If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)

If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report

If you want to undo deduplication, reply with:
#syz undup