syzbot


INFO: rcu detected stall in validate_mm (2)

Status: upstream: reported on 2025/02/03 21:26
Reported-by: syzbot+022b50cd692aa01556aa@syzkaller.appspotmail.com
First crash: 142d, last: 19d
Similar bugs (4)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: rcu detected stall in validate_mm (3) mm C error 35 21d 410d 0/29 upstream: reported C repro on 2024/05/12 09:19
upstream INFO: rcu detected stall in validate_mm (2) mm 2 597d 608d 0/29 auto-obsoleted due to no activity on 2024/02/04 15:00
linux-6.1 INFO: rcu detected stall in validate_mm 6 260d 327d 0/3 auto-obsoleted due to no activity on 2025/01/16 23:39
linux-5.15 INFO: rcu detected stall in validate_mm origin:lts-only syz 1 3d02h 3d02h 0/3 upstream: reported syz repro on 2025/06/23 12:02

Sample crash report:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P8966/1:b..l
	(detected by 0, t=10502 jiffies, g=43561, q=32 ncpus=2)
task:rm              state:R  running task     stack:24352 pid:8966  ppid:8871   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:mas_validate_parent_slot lib/maple_tree.c:-1 [inline]
RIP: 0010:mt_validate+0x1035/0x4c90 lib/maple_tree.c:7237
Code: 83 f7 48 c7 c7 e0 e1 e2 96 be 04 00 00 00 e8 a2 18 d5 f7 f0 ff 05 ab a9 e5 0c eb 18 4d 39 e5 0f 84 0b 01 00 00 e8 2b 9e 83 f7 <49> bc 00 00 00 00 00 fc ff df 48 39 5c 24 28 0f 84 c3 01 00 00 e8
RSP: 0018:ffffc9000d2bf6e0 EFLAGS: 00000293
RAX: ffffffff89fd3845 RBX: 0000000000000000 RCX: ffff88801dfd0000
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffffc9000d2bf8b0 R08: 0000000000000004 R09: 0000000000000003
R10: fffffbfff2dc5c3c R11: 1ffffffff2dc5c3c R12: ffff88807bcea00c
R13: ffff88802c3f760c R14: 0000000000000001 R15: ffff88807bceba50
 validate_mm_mt+0xcd/0x420 mm/mmap.c:294
 validate_mm+0xcc/0x2b0 mm/mmap.c:331
 mmap_region+0x7aa/0x1d30 mm/mmap.c:2910
 do_mmap+0x894/0xf30 mm/mmap.c:1424
 vm_mmap_pgoff+0x1b2/0x2b0 mm/util.c:520
 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: 0033:0x7fcba5c60242
RSP: 002b:00007ffefaf2eff8 EFLAGS: 00000246 ORIG_RAX: 0000000000000009
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fcba5c60242
RDX: 0000000000000003 RSI: 0000000000002000 RDI: 0000000000000000
RBP: 0000000000000022 R08: 00000000ffffffff R09: 0000000000000000
R10: 0000000000000022 R11: 0000000000000246 R12: 0000000000002000
R13: 0000000000000000 R14: 00007fcba5c3c0c0 R15: 00007fcba5b8155b
 </TASK>
rcu: rcu_preempt kthread starved for 10511 jiffies! g43561 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 6.1.141-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:736
Code: 48 89 df e8 47 d4 b8 f7 e9 4c ff ff ff e8 bd 15 f6 ff 00 00 cc cc 00 00 cc cc 00 00 cc cc 00 66 90 0f 00 2d 17 24 4d 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:ffffffff8c607d88 EFLAGS: 000002c6
RAX: 98c34a4008f38000 RBX: ffffffff8a197f77 RCX: 98c34a4008f38000
RDX: 0000000000000001 RSI: ffffffff8a6bffe0 RDI: ffffffff8abf1360
RBP: ffffffff8c607ec0 R08: dffffc0000000000 R09: ffffed10171c6af6
R10: ffffed10171c6af6 R11: 1ffff110171c6af5 R12: 0000000000000000
R13: dffffc0000000000 R14: ffffffff8c6bc680 R15: 1ffffffff1bfd0f6
FS:  0000000000000000(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fc4f7b71d60 CR3: 000000007bc0f000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 3a810b1eb6134bdc DR6: 00000000ffff0ff0 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 (7):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/06/06 16:20 linux-6.1.y 58485ff1a74f 9fa58bba .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in validate_mm
2025/05/29 00:12 linux-6.1.y da3c5173c55f 3d2f584d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in validate_mm
2025/05/24 07:12 linux-6.1.y da3c5173c55f ed351ea7 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in validate_mm
2025/05/23 06:13 linux-6.1.y da3c5173c55f fa44301a .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in validate_mm
2025/03/08 06:32 linux-6.1.y 6ae7ac5c4251 7e3bd60d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in validate_mm
2025/02/20 15:43 linux-6.1.y 0cbb5f65e52f 50668798 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in validate_mm
2025/02/03 21:26 linux-6.1.y 0cbb5f65e52f a21a8419 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in validate_mm
* Struck through repros no longer work on HEAD.