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: 243d, last: 14d
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 365d 365d 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 652d 669d 28/29 fixed on 2024/10/22 11:57
upstream INFO: rcu detected stall in do_vmi_munmap mm 1 17 904d 1132d 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): P8910/1:b..l
rcu: 	(detected by 0, t=10502 jiffies, g=31601, q=264 ncpus=2)
task:dhcpcd-run-hook state:R  running task     stack:24232 pid:8910  ppid:5437   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:check_region_inline mm/kasan/generic.c:169 [inline]
RIP: 0010:kasan_check_range+0x10/0x290 mm/kasan/generic.c:187
Code: c0 c3 0f 0b b8 ea ff ff ff c3 0f 0b b8 ea ff ff ff c3 cc cc cc cc cc cc cc cc 66 0f 1f 00 b0 01 48 85 f6 0f 84 b4 01 00 00 55 <41> 57 41 56 41 55 41 54 53 4c 8d 04 37 49 39 f8 0f 82 13 02 00 00
RSP: 0018:ffffc9000455f350 EFLAGS: 00000202
RAX: ffffffff8a75b001 RBX: 0000000000000001 RCX: ffffffff8a75b103
RDX: 0000000000000001 RSI: 0000000000000004 RDI: ffffffff976ee580
RBP: ffffc9000455f510 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffffbfff2eddcb4 R12: ffff888077acb20c
R13: ffff888077acb20c R14: 0000000000000001 R15: ffff888077aca858
 instrument_atomic_read_write include/linux/instrumented.h:96 [inline]
 atomic_inc include/linux/atomic/atomic-instrumented.h:435 [inline]
 mas_validate_parent_slot lib/maple_tree.c:7046 [inline]
 mt_validate+0x843/0x4400 lib/maple_tree.c:7230
 validate_mm+0xc6/0x450 mm/mmap.c:288
 __split_vma+0xad4/0xc60 mm/mmap.c:2425
 do_vmi_align_munmap+0x3d0/0x16d0 mm/mmap.c:2514
 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+0x55/0xb0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f5602e60242
RSP: 002b:00007ffd834125e8 EFLAGS: 00000206 ORIG_RAX: 0000000000000009
RAX: ffffffffffffffda RBX: 00007f5602b3a000 RCX: 00007f5602e60242
RDX: 0000000000000001 RSI: 0000000000002000 RDI: 00007f5602b3a000
RBP: 0000000000000812 R08: 0000000000000003 R09: 0000000000005000
R10: 0000000000000812 R11: 0000000000000206 R12: 00007ffd83412670
R13: 00007f5602b3f0c0 R14: 00007ffd83412a20 R15: 00000fffb06824c0
 </TASK>
rcu: rcu_preempt kthread starved for 10537 jiffies! g31601 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:26920 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:
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 0 Comm: swapper/1 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
RIP: 0010:pv_native_safe_halt+0xf/0x10 arch/x86/kernel/paravirt.c:148
Code: 88 1f 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 43 e4 3f 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:ffffc90000187de0 EFLAGS: 000002c2
RAX: fce314fac819c800 RBX: ffffffff8162ae21 RCX: fce314fac819c800
RDX: 0000000000000001 RSI: ffffffff8acacbe0 RDI: ffffffff8b1c9c20
RBP: ffffc90000187f20 R08: ffff8880b8f36bab R09: 1ffff110171e6d75
R10: dffffc0000000000 R11: ffffed10171e6d76 R12: 1ffff92000030fc8
R13: dffffc0000000000 R14: 1ffff110036cd780 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f6295987cc0 CR3: 000000000cf32000 CR4: 00000000003506e0
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:178 [inline]
 do_idle+0x221/0x590 kernel/sched/idle.c:302
 cpu_startup_entry+0x43/0x60 kernel/sched/idle.c:401
 start_secondary+0xee/0xf0 arch/x86/kernel/smpboot.c:323
 secondary_startup_64_no_verify+0x179/0x17b
 </TASK>

Crashes (8):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/06/05 15:33 linux-6.6.y 924b4a879cbb 48b6c3fa .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: rcu detected stall in do_vmi_munmap
2026/04/21 10:44 linux-6.6.y 9760bf04666d 3f2e655b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: rcu detected stall in do_vmi_munmap
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.