INFO: rcu detected stall in do_mas_munmap (2)

Status: upstream: reported syz repro on 2025/03/26 06:55
Bug presence: origin:upstream
[Documentation on labels]
Reported-by: syzbot+009b2a7f9d8a0615cf9b@syzkaller.appspotmail.com
First crash: 509d, last: 7d09h
▶ ▼ Bug presence (1)
Date Name Commit Repro Result
2026/01/03 upstream (ToT) aacb0a6d604a syz [report] INFO: rcu detected stall in sys_newfstatat
▶ ▼ 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 677d 800d 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 1295d 1357d 0/29 auto-obsoleted due to no activity on 2023/04/29 23:21
▶ ▼ Fix bisection attempts (2)
Created Duration User Patch Repo Result
2026/08/09 20:43 2h35m bisect fix linux-6.1.y OK (0) job log log
2026/06/26 22:21 2h36m bisect fix linux-6.1.y OK (0) job log log

Sample crash report:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P4534/1:b..l
	(detected by 0, t=10503 jiffies, g=12169, q=563 ncpus=2)
task:modprobe        state:R  running task     stack:24336 pid:4534  ppid:4342   flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5245 [inline]
 __schedule+0x11d1/0x40e0 kernel/sched/core.c:6562
 preempt_schedule_irq+0xbb/0x160 kernel/sched/core.c:6874
 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:lock_is_held_type+0x13a/0x190 kernel/locking/lockdep.c:5710
Code: 75 40 48 c7 04 24 00 00 00 00 9c 8f 04 24 f7 04 24 00 02 00 00 75 46 41 f7 c5 00 02 00 00 74 01 fb 65 48 8b 04 25 28 00 00 00 <48> 3b 44 24 08 75 3c 89 e8 48 83 c4 10 5b 41 5c 41 5d 41 5e 41 5f
RSP: 0018:ffffc900040c7178 EFLAGS: 00000206
RAX: f99a529c8d04c200 RBX: ffff88802c669dc0 RCX: f99a529c8d04c200
RDX: 0000000000000000 RSI: ffffffff8a8c2220 RDI: ffffffff8adf0d20
RBP: 0000000000000001 R08: ffff88802c669dc0 R09: 0000000000000003
R10: 0000000000000003 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000246 R14: ffff888018add3d8 R15: ffff88802c66a8a0
 lock_is_held include/linux/lockdep.h:283 [inline]
 mt_locked lib/maple_tree.c:-1 [inline]
 mt_slot lib/maple_tree.c:816 [inline]
 mas_slot lib/maple_tree.c:849 [inline]
 mt_validate_nulls lib/maple_tree.c:7193 [inline]
 mt_validate+0x43d1/0x4cb0 lib/maple_tree.c:7249
 validate_mm_mt+0xe2/0x440 mm/mmap.c:295
 validate_mm+0xe1/0x2e0 mm/mmap.c:332
 __vma_adjust+0x1855/0x1cd0 mm/mmap.c:879
 vma_adjust include/linux/mm.h:2810 [inline]
 __split_vma+0x3a7/0x500 mm/mmap.c:-1
 do_mas_align_munmap+0x397/0x12b0 mm/mmap.c:2480
 do_mas_munmap+0x240/0x2b0 mm/mmap.c:2650
 __mmap_region mm/mmap.c:2698 [inline]
 mmap_region+0x6e0/0x1ca0 mm/mmap.c:2916
 do_mmap+0x964/0xfd0 mm/mmap.c:1436
 vm_mmap_pgoff+0x1c1/0x2d0 mm/util.c:520
 ksys_mmap_pgoff+0x516/0x6f0 mm/mmap.c:1482
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f758aea4242
RSP: 002b:00007fff12210fc8 EFLAGS: 00000206 ORIG_RAX: 0000000000000009
RAX: ffffffffffffffda RBX: 00007f758ab8d000 RCX: 00007f758aea4242
RDX: 0000000000000005 RSI: 000000000001c000 RDI: 00007f758ab8d000
RBP: 0000000000000812 R08: 0000000000000000 R09: 0000000000008000
R10: 0000000000000812 R11: 0000000000000206 R12: 00007fff12211018
R13: 00007f758ae81ab0 R14: 00007fff12211440 R15: 00000fffe24421fc
 </TASK>
rcu: rcu_preempt kthread starved for 10531 jiffies! g12169 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:27760 pid:16    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5245 [inline]
 __schedule+0x11d1/0x40e0 kernel/sched/core.c:6562
 schedule+0xb9/0x180 kernel/sched/core.c:6638
 schedule_timeout+0x184/0x2d0 kernel/time/timer.c:2168
 rcu_gp_fqs_loop+0x303/0x1340 kernel/rcu/tree.c:1706
 rcu_gp_kthread+0x99/0x3b0 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:
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 56 Comm: kworker/u4:4 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
Workqueue: events_unbound toggle_allocation_gate
RIP: 0010:csd_lock_wait kernel/smp.c:424 [inline]
RIP: 0010:smp_call_function_many_cond+0xea2/0x1290 kernel/smp.c:998
Code: 00 00 00 41 8b 1f 89 de 83 e6 01 31 ff e8 e6 f6 0a 00 83 e3 01 48 bb 00 00 00 00 00 fc ff df 75 07 e8 72 f3 0a 00 eb 37 f3 90 <41> 0f b6 04 1c 84 c0 75 10 41 f7 07 01 00 00 00 74 1e e8 57 f3 0a
RSP: 0018:ffffc90001577800 EFLAGS: 00000293
RAX: ffffffff81778139 RBX: dffffc0000000000 RCX: ffff88801eedbb80
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffffc90001577960 R08: ffffffff90af7247 R09: 1ffffffff215ee48
R10: dffffc0000000000 R11: fffffbfff215ee49 R12: 1ffff110171c8601
R13: ffff8880b8f3bbc0 R14: 0000000000000000 R15: ffff8880b8e43008
FS:  0000000000000000(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000020000006b000 CR3: 000000000c88e000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 on_each_cpu_cond_mask+0x3b/0x80 kernel/smp.c:1165
 on_each_cpu include/linux/smp.h:71 [inline]
 text_poke_sync arch/x86/kernel/alternative.c:1574 [inline]
 text_poke_bp_batch+0x2b7/0x850 arch/x86/kernel/alternative.c:1774
 text_poke_flush arch/x86/kernel/alternative.c:1965 [inline]
 text_poke_finish+0x16/0x30 arch/x86/kernel/alternative.c:1972
 arch_jump_label_transform_apply+0x13/0x20 arch/x86/kernel/jump_label.c:146
 static_key_enable_cpuslocked+0x11f/0x240 kernel/jump_label.c:207
 static_key_enable+0x16/0x20 kernel/jump_label.c:220
 toggle_allocation_gate+0xba/0x470 mm/kfence/core.c:821
 process_one_work+0x8a2/0x1160 kernel/workqueue.c:2292
 worker_thread+0xaa2/0x1270 kernel/workqueue.c:2439
 kthread+0x29d/0x330 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>

Crashes (29):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/04/04 21:40 linux-6.1.y 1989cd3d56e2 4440e7c2 .config console log report syz / log [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in do_mas_munmap
2025/12/16 01:57 linux-6.1.y 50cbba13faa2 d6526ea3 .config console log report syz / log [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in do_mas_munmap
2026/05/25 23:45 linux-6.1.y dcbcab9d7079 c69befb3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in do_mas_munmap
2026/05/21 17:49 linux-6.1.y c27210688955 e195359d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in do_mas_munmap
2026/05/21 04:35 linux-6.1.y c27210688955 41b8c833 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in do_mas_munmap
2026/05/19 01:14 linux-6.1.y c27210688955 9f74d399 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in do_mas_munmap
2026/04/20 05:36 linux-6.1.y 7c87defbd336 303e2802 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-perf INFO: rcu detected stall in do_mas_munmap
2026/04/17 03:27 linux-6.1.y 8e8fc038cad5 de0a551d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in do_mas_munmap
2026/03/17 02:10 linux-6.1.y f2ddafa93a25 0737c18f .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in do_mas_munmap
2026/02/23 02:40 linux-6.1.y 779f9571ac3e 6e7b5511 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in do_mas_munmap
2026/02/20 23:50 linux-6.1.y 779f9571ac3e 6e7b5511 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in do_mas_munmap
2026/02/11 07:28 linux-6.1.y 0182cb5b74ee 441e25b7 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in do_mas_munmap
2026/01/27 08:50 linux-6.1.y cd9b81672742 efb3e894 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in do_mas_munmap
2026/01/08 02:18 linux-6.1.y 50cbba13faa2 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in do_mas_munmap
2025/12/25 04:23 linux-6.1.y 50cbba13faa2 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in do_mas_munmap
2025/12/23 07:39 linux-6.1.y 50cbba13faa2 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in do_mas_munmap
2025/12/02 12:25 linux-6.1.y f6e38ae624cf d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in do_mas_munmap
2025/11/13 17:57 linux-6.1.y f6e38ae624cf 07e030de .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in do_mas_munmap
2025/10/30 06:14 linux-6.1.y f6e38ae624cf fd2207e7 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in do_mas_munmap
2025/10/20 01:49 linux-6.1.y 8e6e2188d949 1c8c8cd8 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in do_mas_munmap
2025/09/25 04:04 linux-6.1.y 363a599da6d9 0abd0691 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in do_mas_munmap
2025/09/10 15:40 linux-6.1.y f97f1002271b fdeaa69b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in do_mas_munmap
2025/08/14 01:16 linux-6.1.y 3594f306da12 22ec1469 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in do_mas_munmap
2025/07/17 07:20 linux-6.1.y f2198ea7eb3e 44f8051e .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in do_mas_munmap
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.