syzbot


INFO: rcu detected stall in do_vmi_munmap (2)

Status: upstream: reported on 2025/10/19 13:51
Reported-by: syzbot+463b5f1343c74e3819d3@syzkaller.appspotmail.com
First crash: 136d, last: 32d
Similar bugs (3)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.6 INFO: rcu detected stall in do_vmi_munmap 1 1 259d 259d 0/2 auto-obsoleted due to no activity on 2025/09/27 01:25
upstream INFO: rcu detected stall in do_vmi_munmap (2) mm 1 40 546d 562d 28/29 fixed on 2024/10/22 11:57
upstream INFO: rcu detected stall in do_vmi_munmap mm 1 17 798d 1026d 0/29 auto-obsoleted due to no activity on 2024/03/27 03:06

Sample crash report:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P18949/1:b..l
rcu: 	(detected by 0, t=10502 jiffies, g=153105, q=297 ncpus=2)
task:rm              state:R  running task     stack:24232 pid:18949 ppid:18921  flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5381 [inline]
 __schedule+0x1553/0x45a0 kernel/sched/core.c:6700
 preempt_schedule_irq+0xbf/0x150 kernel/sched/core.c:7010
 irqentry_exit+0x67/0x70 kernel/entry/common.c:438
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:687
RIP: 0010:debug_lockdep_rcu_enabled+0x29/0x30 kernel/rcu/update.c:320
Code: cc f3 0f 1e fa 31 c0 83 3d ff 9e 06 04 00 74 1d 83 3d 86 d2 06 04 00 74 14 65 48 8b 0d d0 73 7f 75 31 c0 83 b9 dc 0a 00 00 00 <0f> 94 c0 c3 cc cc cc 66 0f 1f 00 48 8b 3c 24 e8 43 fb ff ff 66 90
RSP: 0018:ffffc9000512f358 EFLAGS: 00000246
RAX: 0000000000000000 RBX: ffff88807e3a8040 RCX: ffff8880220c3c00
RDX: 0000000000000000 RSI: ffffffff8e72cad0 RDI: 0000000000000001
RBP: ffffc9000512f510 R08: ffff8880220c3c00 R09: 0000000000000003
R10: 0000000000000002 R11: 0000000000000000 R12: ffff88805fd8aa80
R13: 00007ffc633b8fff R14: ffff88805fd8aad0 R15: 000000ca880f6000
 mt_slot lib/maple_tree.c:814 [inline]
 mas_slot lib/maple_tree.c:847 [inline]
 mas_get_slot lib/maple_tree.c:6690 [inline]
 mas_validate_gaps lib/maple_tree.c:6959 [inline]
 mt_validate+0x262a/0x4400 lib/maple_tree.c:7234
 validate_mm+0xc6/0x450 mm/mmap.c:288
 __split_vma+0xa6f/0xc60 mm/mmap.c:2425
 do_vmi_align_munmap+0x32a/0x16d0 mm/mmap.c:2501
 do_vmi_munmap+0x252/0x2d0 mm/mmap.c:2660
 __mmap_region mm/mmap.c:2710 [inline]
 mmap_region+0x773/0x2000 mm/mmap.c:2941
 do_mmap+0x92c/0x10a0 mm/mmap.c:1385
 vm_mmap_pgoff+0x1c4/0x3f0 mm/util.c:556
 ksys_mmap_pgoff+0x520/0x700 mm/mmap.c:1431
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f31db28d242
RSP: 002b:00007ffc633b6448 EFLAGS: 00000206 ORIG_RAX: 0000000000000009
RAX: ffffffffffffffda RBX: 00007f31daf76000 RCX: 00007f31db28d242
RDX: 0000000000000005 RSI: 000000000001c000 RDI: 00007f31daf76000
RBP: 0000000000000812 R08: 0000000000000003 R09: 0000000000008000
R10: 0000000000000812 R11: 0000000000000206 R12: 00007ffc633b6498
R13: 00007f31db26aab0 R14: 00007ffc633b68c0 R15: 00000fff8c676c8c
 </TASK>
rcu: rcu_preempt kthread starved for 10536 jiffies! g153105 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:25872 pid:17    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5381 [inline]
 __schedule+0x1553/0x45a0 kernel/sched/core.c:6700
 schedule+0xbd/0x170 kernel/sched/core.c:6774
 schedule_timeout+0x188/0x2d0 kernel/time/timer.c:2168
 rcu_gp_fqs_loop+0x313/0x1590 kernel/rcu/tree.c:1667
 rcu_gp_kthread+0x9d/0x3b0 kernel/rcu/tree.c:1866
 kthread+0x2fa/0x390 kernel/kthread.c:388
 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
CPU: 0 PID: 0 Comm: swapper/0 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:pv_native_safe_halt+0xf/0x10 arch/x86/kernel/paravirt.c:148
Code: f8 22 02 c3 cc cc cc cc cc cc cc f3 0f 1e fa 0f 0b 66 2e 0f 1f 84 00 00 00 00 00 f3 0f 1e fa 66 90 0f 00 2d 33 02 44 00 fb f4 <c3> 66 0f 1f 00 55 41 57 41 56 41 54 53 50 8b 2f eb 2e 41 89 de 80
RSP: 0018:ffffffff8ce07d80 EFLAGS: 000002c2
RAX: ea738651e9d2fb00 RBX: ffffffff8162a490 RCX: ea738651e9d2fb00
RDX: 0000000000000001 RSI: ffffffff8acac900 RDI: ffffffff8b1c81e0
RBP: ffffffff8ce07eb8 R08: ffff8880b8e36b2b R09: 1ffff110171c6d65
R10: dffffc0000000000 R11: ffffed10171c6d66 R12: 1ffffffff19d2688
R13: 1ffffffff19c0fbc R14: 0000000000000000 R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f6eb3e17dac CR3: 000000007f33b000 CR4: 00000000003506f0
DR0: ffffffffffffffff DR1: 00000000000001f8 DR2: 0000000000000083
DR3: ffffffffefffff15 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 arch_safe_halt arch/x86/include/asm/paravirt.h:108 [inline]
 default_idle+0x13/0x20 arch/x86/kernel/process.c:753
 default_idle_call+0x6c/0xa0 kernel/sched/idle.c:97
 cpuidle_idle_call kernel/sched/idle.c:170 [inline]
 do_idle+0x1f0/0x4e0 kernel/sched/idle.c:282
 cpu_startup_entry+0x43/0x60 kernel/sched/idle.c:380
 rest_init+0x2e2/0x300 init/main.c:744
 arch_call_rest_init+0xe/0x10 init/main.c:841
 start_kernel+0x459/0x4e0 init/main.c:1086
 x86_64_start_reservations+0x2a/0x30 arch/x86/kernel/head64.c:555
 x86_64_start_kernel+0x60/0x60 arch/x86/kernel/head64.c:536
 secondary_startup_64_no_verify+0x179/0x17b
 </TASK>

Crashes (6):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/01/31 09:48 linux-6.6.y 2cf6f68313dc c75a2f6e .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: rcu detected stall in do_vmi_munmap
2025/12/26 15:33 linux-6.6.y 5fa4793a2d2d d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: rcu detected stall in do_vmi_munmap
2025/12/06 16:10 linux-6.6.y 4791134e4aeb d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: rcu detected stall in do_vmi_munmap
2025/11/05 16:52 linux-6.6.y 0a805b6ea8cd a6c9c731 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: rcu detected stall in do_vmi_munmap
2025/11/05 14:34 linux-6.6.y 0a805b6ea8cd a6c9c731 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: rcu detected stall in do_vmi_munmap
2025/10/19 13:50 linux-6.6.y 0bbbd97a442d 1c8c8cd8 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: rcu detected stall in do_vmi_munmap
* Struck through repros no longer work on HEAD.