syzbot


INFO: rcu detected stall in do_mas_munmap (2)

Status: upstream: reported on 2025/03/26 06:55
Reported-by: syzbot+009b2a7f9d8a0615cf9b@syzkaller.appspotmail.com
First crash: 110d, last: 20h20m
Similar bugs (2)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.1 INFO: rcu detected stall in do_mas_munmap 1 12 279d 401d 0/3 auto-obsoleted due to no activity on 2025/01/16 11:56
upstream INFO: rcu detected stall in do_mas_munmap kernel 1 3 896d 959d 0/29 auto-obsoleted due to no activity on 2023/04/29 23:21

Sample crash report:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P29052/1:b..l
	(detected by 0, t=10502 jiffies, g=210645, q=133 ncpus=2)
task:modprobe        state:R  running task     stack:24352 pid:29052 ppid:5520   flags:0x00004000
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:instrument_atomic_read_write include/linux/instrumented.h:102 [inline]
RIP: 0010:atomic_inc include/linux/atomic/atomic-instrumented.h:190 [inline]
RIP: 0010:mt_validate_nulls lib/maple_tree.c:7193 [inline]
RIP: 0010:mt_validate+0x442d/0x4c90 lib/maple_tree.c:7244
Code: 7b f7 4c 0b 64 24 20 0f 84 bb 02 00 00 e8 6b 2b 7b f7 48 c7 c7 40 83 05 97 be 04 00 00 00 e8 aa a8 cc f7 f0 ff 05 03 d7 ff 0c <48> c7 c7 60 83 05 97 be 04 00 00 00 e8 92 a8 cc f7 f0 ff 05 0b d7
RSP: 0018:ffffc900034973c0 EFLAGS: 00000207
RAX: ffffffff8a05ac01 RBX: 0000000000000007 RCX: ffffffff8a05ac36
RDX: 0000000000000001 RSI: 0000000000000004 RDI: ffffffff97058340
RBP: ffffc90003497590 R08: 0000000000000004 R09: 0000000000000003
R10: fffffbfff2e0b068 R11: 1ffffffff2e0b068 R12: ffff888073cf3438
R13: ffff888056358280 R14: 0000000000000001 R15: 0000000000000300
 validate_mm_mt+0xcd/0x420 mm/mmap.c:294
 validate_mm+0xcc/0x2b0 mm/mmap.c:331
 do_mas_align_munmap+0xfad/0x1220 mm/mmap.c:2595
 do_mas_munmap+0x240/0x2b0 mm/mmap.c:2646
 __mmap_region mm/mmap.c:2694 [inline]
 mmap_region+0x713/0x1d30 mm/mmap.c:2912
 do_mmap+0x894/0xf30 mm/mmap.c:1432
 vm_mmap_pgoff+0x1b2/0x2b0 mm/util.c:520
 ksys_mmap_pgoff+0x516/0x6f0 mm/mmap.c:1478
 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: 0033:0x7fe19e2b8242
RSP: 002b:00007fff1ab893e8 EFLAGS: 00000206 ORIG_RAX: 0000000000000009
RAX: ffffffffffffffda RBX: 00007fe19e01a000 RCX: 00007fe19e2b8242
RDX: 0000000000000005 RSI: 000000000014e000 RDI: 00007fe19e01a000
RBP: 0000000000000812 R08: 0000000000000000 R09: 0000000000028000
R10: 0000000000000812 R11: 0000000000000206 R12: 00007fff1ab89438
R13: 00007fe19e2945f0 R14: 00007fff1ab89c20 R15: 00000fffe3571280
 </TASK>
rcu: rcu_preempt kthread starved for 6386 jiffies! g210645 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:
CPU: 0 PID: 0 Comm: swapper/0 Not tainted 6.1.144-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
RIP: 0010:default_idle+0xb/0x10 arch/x86/kernel/process.c:742
Code: 48 89 df e8 a7 89 b0 f7 e9 4c ff ff ff e8 5d 07 f6 ff 00 00 cc cc 00 00 cc cc 00 00 cc cc 00 66 90 0f 00 2d 67 d5 64 00 fb f4 <c3> 0f 1f 40 00 41 57 41 56 53 49 be 00 00 00 00 00 fc ff df 65 48
RSP: 0018:ffffffff8c807d88 EFLAGS: 000002c6
RAX: 9672272b937ce800 RBX: ffffffff8a21ce87 RCX: 9672272b937ce800
RDX: 0000000000000001 RSI: ffffffff8a8c0460 RDI: ffffffff8adf1c20
RBP: ffffffff8c807ec0 R08: dffffc0000000000 R09: ffffed10171c6af6
R10: ffffed10171c6af6 R11: 1ffff110171c6af5 R12: 0000000000000000
R13: dffffc0000000000 R14: ffffffff8c8bc680 R15: 1ffffffff1c3ed06
FS:  0000000000000000(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f1573fffd58 CR3: 0000000073547000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 default_idle_call+0x84/0xc0 kernel/sched/idle.c:109
 cpuidle_idle_call kernel/sched/idle.c:191 [inline]
 do_idle+0x1fc/0x570 kernel/sched/idle.c:303
 cpu_startup_entry+0x3f/0x60 kernel/sched/idle.c:401
 rest_init+0x2dc/0x300 init/main.c:733
 arch_call_rest_init+0xa/0xa init/main.c:893
 start_kernel+0x490/0x539 init/main.c:1140
 secondary_startup_64_no_verify+0xcf/0xdb
 </TASK>

Crashes (5):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/07/13 22:44 linux-6.1.y dfc486ec9cce 3cda49cf .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in do_mas_munmap
2025/06/23 10:14 linux-6.1.y 58485ff1a74f d6cdfb8a .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in do_mas_munmap
2025/06/15 01:20 linux-6.1.y 58485ff1a74f 5f4b362d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in do_mas_munmap
2025/06/04 18:46 linux-6.1.y 58485ff1a74f e565f08d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in do_mas_munmap
2025/03/26 06:54 linux-6.1.y 344a09659766 89d30d73 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in do_mas_munmap
* Struck through repros no longer work on HEAD.