syzbot

 sign-in | mailing list | source | docs
🐞 Open [1422]
≡ Subsystems
🐞 Fixed [6980]
🐞 Invalid [18196]
⬇ Missing Backports [223]
≡ Crashes
Kernel Health Bugs/Month Bug Lifetimes Fuzzing
Total Repo Heatmap Subsystems Heatmap
✨ AI
💬 Send us feedback

INFO: rcu detected stall in mas_store_prealloc (4)

Status: auto-obsoleted due to no activity on 2025/12/24 05:56
Subsystems: mm
[Documentation on labels]
First crash: 168d, last: 168d
▶ ▼ Similar bugs (4)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: rcu detected stall in mas_store_prealloc (2) mm 1 2 503d 510d 0/29 auto-obsoleted due to no activity on 2025/01/22 20:20
upstream INFO: rcu detected stall in mas_store_prealloc (3) mm 1 1 280d 280d 0/29 auto-obsoleted due to no activity on 2025/09/03 06:15
upstream INFO: rcu detected stall in mas_store_prealloc mm 1 1 970d 970d 0/29 auto-obsoleted due to no activity on 2023/10/13 16:47
linux-6.1 INFO: rcu detected stall in mas_store_prealloc 1 1 628d 628d 0/3 auto-obsoleted due to no activity on 2024/09/30 04:09

Sample crash report:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P13/1:b..l P10104/1:b..l
rcu: 	(detected by 0, t=10502 jiffies, g=46349, q=963 ncpus=2)
task:rm              state:R  running task     stack:23592 pid:10104 tgid:10104 ppid:10070  task_flags:0x400000 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5357 [inline]
 __schedule+0x1798/0x4cc0 kernel/sched/core.c:6961
 preempt_schedule_irq+0xb5/0x150 kernel/sched/core.c:7288
 irqentry_exit+0x6f/0x90 kernel/entry/common.c:197
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
RIP: 0010:native_save_fl arch/x86/include/asm/irqflags.h:32 [inline]
RIP: 0010:arch_local_save_flags arch/x86/include/asm/irqflags.h:109 [inline]
RIP: 0010:arch_local_irq_save arch/x86/include/asm/irqflags.h:127 [inline]
RIP: 0010:lock_release+0xaa/0x3e0 kernel/locking/lockdep.c:5885
Code: 92 41 83 bf ec 0a 00 00 00 0f 85 1e 02 00 00 49 81 3e 20 a3 64 93 0f 84 11 02 00 00 48 c7 44 24 20 00 00 00 00 9c 8f 44 24 20 <48> 8b 5c 24 20 fa 48 c7 c7 12 df 9c 8d e8 64 03 dd 09 65 ff 05 0d
RSP: 0018:ffffc9000bb7e390 EFLAGS: 00000202
RAX: 0000000000000000 RBX: ffffffff90375901 RCX: 277f67cec778bd00
RDX: ffffc9000bb7e501 RSI: ffffffff8be33f60 RDI: ffffffff8be33f20
RBP: dffffc0000000000 R08: ffffc9000bb7e990 R09: ffffc9000bb7e518
R10: dffffc0000000000 R11: fffff5200176fca5 R12: ffffc9000bb7e9a0
R13: ffffffff8172c195 R14: ffffffff8e13a0e0 R15: ffff88802ccb8000
 rcu_lock_release include/linux/rcupdate.h:341 [inline]
 rcu_read_unlock include/linux/rcupdate.h:871 [inline]
 class_rcu_destructor include/linux/rcupdate.h:1155 [inline]
 unwind_next_frame+0x19a9/0x2390 arch/x86/kernel/unwind_orc.c:680
 arch_stack_walk+0x11c/0x150 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0x9c/0xe0 kernel/stacktrace.c:122
 kasan_save_stack+0x3e/0x60 mm/kasan/common.c:47
 kasan_record_aux_stack+0xbd/0xd0 mm/kasan/generic.c:548
 __call_rcu_common kernel/rcu/tree.c:3123 [inline]
 call_rcu+0x157/0x9c0 kernel/rcu/tree.c:3243
 ma_free_rcu lib/maple_tree.c:211 [inline]
 mas_topiary_node lib/maple_tree.c:2527 [inline]
 mas_topiary_replace lib/maple_tree.c:2634 [inline]
 mas_wmb_replace+0x1756/0x25f0 lib/maple_tree.c:2651
 mas_split lib/maple_tree.c:3390 [inline]
 mas_commit_b_node+0xabf/0xf70 lib/maple_tree.c:3410
 mas_wr_bnode lib/maple_tree.c:4079 [inline]
 mas_wr_store_entry+0x50f/0x25b0 lib/maple_tree.c:4111
 mas_store_prealloc+0xb00/0xf60 lib/maple_tree.c:5510
 vma_iter_store_new mm/vma.h:508 [inline]
 __mmap_new_vma mm/vma.c:2497 [inline]
 __mmap_region mm/vma.c:2669 [inline]
 mmap_region+0x1b5e/0x20c0 mm/vma.c:2739
 do_mmap+0xc45/0x10d0 mm/mmap.c:558
 vm_mmap_pgoff+0x2a6/0x4d0 mm/util.c:580
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f8b39f70242
RSP: 002b:00007ffec0175508 EFLAGS: 00000246 ORIG_RAX: 0000000000000009
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f8b39f70242
RDX: 0000000000000003 RSI: 0000000000002000 RDI: 0000000000000000
RBP: 0000000000000022 R08: 00000000ffffffff R09: 0000000000000000
R10: 0000000000000022 R11: 0000000000000246 R12: 0000000000002000
R13: 0000000000000001 R14: 000000ee1b9ebdc7 R15: 0000000000000000
 </TASK>
task:kworker/u8:1    state:R  running task     stack:21504 pid:13    tgid:13    ppid:2      task_flags:0x4208060 flags:0x00004000
Workqueue: bat_events batadv_nc_worker
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5357 [inline]
 __schedule+0x1798/0x4cc0 kernel/sched/core.c:6961
 preempt_schedule_irq+0xb5/0x150 kernel/sched/core.c:7288
 irqentry_exit+0x6f/0x90 kernel/entry/common.c:197
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
RIP: 0010:lock_release+0x20/0x3e0 kernel/locking/lockdep.c:5876
Code: 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 55 41 57 41 56 41 55 41 54 53 48 83 ec 30 49 89 f5 49 89 fe 65 48 8b 05 a0 71 03 11 <48> 89 44 24 28 0f 1f 44 00 00 65 8b 05 a3 71 03 11 83 f8 08 0f 83
RSP: 0018:ffffc900001279b8 EFLAGS: 00000286
RAX: fdaffbd092fdbd00 RBX: ffff888078cc28c0 RCX: ffff88801ceb8000
RDX: 0000000000000000 RSI: ffffffff8b47e112 RDI: ffffffff8e13a0e0
RBP: fffffffffffffe38 R08: 0000000000000000 R09: ffffffff8b47e112
R10: dffffc0000000000 R11: ffffffff8b47e040 R12: dffffc0000000000
R13: ffffffff8b47e112 R14: ffffffff8e13a0e0 R15: 0000000000000225
 rcu_lock_release include/linux/rcupdate.h:341 [inline]
 rcu_read_unlock include/linux/rcupdate.h:871 [inline]
 batadv_nc_purge_orig_hash net/batman-adv/network-coding.c:412 [inline]
 batadv_nc_worker+0x28c/0x610 net/batman-adv/network-coding.c:719
 process_one_work kernel/workqueue.c:3236 [inline]
 process_scheduled_works+0xae1/0x17b0 kernel/workqueue.c:3319
 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3400
 kthread+0x711/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x439/0x7d0 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
rcu: rcu_preempt kthread starved for 10027 jiffies! g46349 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:27224 pid:16    tgid:16    ppid:2      task_flags:0x208040 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5357 [inline]
 __schedule+0x1798/0x4cc0 kernel/sched/core.c:6961
 __schedule_loop kernel/sched/core.c:7043 [inline]
 schedule+0x165/0x360 kernel/sched/core.c:7058
 schedule_timeout+0x12b/0x270 kernel/time/sleep_timeout.c:99
 rcu_gp_fqs_loop+0x301/0x1540 kernel/rcu/tree.c:2083
 rcu_gp_kthread+0x99/0x390 kernel/rcu/tree.c:2285
 kthread+0x711/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x439/0x7d0 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </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 UID: 0 PID: 0 Comm: swapper/1 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
RIP: 0010:pv_native_safe_halt+0x13/0x20 arch/x86/kernel/paravirt.c:82
Code: 3e ed 95 f5 cc cc cc 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 66 90 0f 00 2d b3 d9 0d 00 f3 0f 1e fa fb f4 <e9> 13 ed 95 f5 cc cc cc cc cc cc cc cc 90 90 90 90 90 90 90 90 90
RSP: 0018:ffffc90000197de0 EFLAGS: 000002c2
RAX: d43ce1f0879ef000 RBX: ffffffff819683f8 RCX: d43ce1f0879ef000
RDX: 0000000000000001 RSI: ffffffff8d9ba32d RDI: ffffffff8be33f80
RBP: ffffc90000197f20 R08: ffff8880b8732f9b R09: 1ffff110170e65f3
R10: dffffc0000000000 R11: ffffed10170e65f4 R12: ffffffff8fa3a830
R13: 0000000000000001 R14: 0000000000000001 R15: 1ffff110039d9b40
FS:  0000000000000000(0000) GS:ffff888125d12000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fd099848304 CR3: 000000004c80f000 CR4: 0000000000350ef0
Call Trace:
 <TASK>
 arch_safe_halt arch/x86/include/asm/paravirt.h:107 [inline]
 default_idle+0x13/0x20 arch/x86/kernel/process.c:757
 default_idle_call+0x74/0xb0 kernel/sched/idle.c:122
 cpuidle_idle_call kernel/sched/idle.c:190 [inline]
 do_idle+0x1e8/0x510 kernel/sched/idle.c:330
 cpu_startup_entry+0x44/0x60 kernel/sched/idle.c:428
 start_secondary+0x101/0x110 arch/x86/kernel/smpboot.c:315
 common_startup_64+0x13e/0x147
 </TASK>
raw-gadget.0 gadget.2: ignoring, device is not running
raw-gadget.0 gadget.2: ignoring, device is not running

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/09/25 05:56 upstream 4ea5af085908 0abd0691 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root INFO: rcu detected stall in mas_store_prealloc
* Struck through repros no longer work on HEAD.