[v6.1] INFO: rcu detected stall in mas_preallocate (2)
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2:54 AM (15 hours ago) 2:54 AM
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Hello,
syzbot found the following issue on:
HEAD commit: fb28aa725e05 Linux 6.1.180
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=10c053b9580000
kernel config: https://syzkaller.appspot.com/x/.config?x=31dfefc4a14efea3
dashboard link: https://syzkaller.appspot.com/bug?extid=fcce605c4e72e3a0be8b
compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
Unfortunately, I don't have any reproducer for this issue yet.
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/9a6fe2a54d0f/disk-fb28aa72.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/742b23a1d931/vmlinux-fb28aa72.xz
kernel image: https://storage.googleapis.com/syzbot-assets/b3f257c16d2e/bzImage-fb28aa72.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+fcce60...@syzkaller.appspotmail.com
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P23809/1:b..l
(detected by 0, t=10502 jiffies, g=149289, q=28 ncpus=1)
task:sed state:R running task stack:24752 pid:23809 ppid:23808 flags:0x00004000
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5246 [inline]
__schedule+0x107f/0x4030 kernel/sched/core.c:6563
preempt_schedule_irq+0xbb/0x160 kernel/sched/core.c:6875
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_acquire+0x225/0x4a0 kernel/locking/lockdep.c:5680
Code: f7 84 24 80 00 00 00 00 02 00 00 43 c6 44 3d 04 f8 0f 85 f0 00 00 00 41 f7 c6 00 02 00 00 74 01 fb 48 c7 44 24 60 0e 36 e0 45 <4b> c7 44 3d 00 00 00 00 00 43 c7 44 3d 08 00 00 00 00 65 48 8b 04
RSP: 0018:ffffc90004d9f420 EFLAGS: 00000206
RAX: 0000000000000001 RBX: 0000000000000000 RCX: 555919c126f75300
RDX: 0000000000000000 RSI: ffffffff8a8c2920 RDI: ffffffff8adf5de0
RBP: ffffc90004d9f538 R08: dffffc0000000000 R09: 1ffffffff2162048
R10: dffffc0000000000 R11: fffffbfff2162049 R12: 0000000000000000
R13: 1ffff920009b3e90 R14: 0000000000000246 R15: dffffc0000000000
rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
rcu_read_lock include/linux/rcupdate.h:791 [inline]
is_bpf_text_address+0x43/0x2a0 kernel/bpf/core.c:735
kernel_text_address+0x9c/0xd0 kernel/extable.c:125
__kernel_text_address+0x9/0x30 kernel/extable.c:79
unwind_get_return_address+0x49/0x80 arch/x86/kernel/unwind_orc.c:323
arch_stack_walk+0xf2/0x140 arch/x86/kernel/stacktrace.c:26
stack_trace_save+0xa6/0xf0 kernel/stacktrace.c:122
kasan_save_stack mm/kasan/common.c:46 [inline]
kasan_set_track+0x4b/0x70 mm/kasan/common.c:53
__kasan_slab_alloc+0x6b/0x80 mm/kasan/common.c:329
kasan_slab_alloc include/linux/kasan.h:201 [inline]
slab_post_alloc_hook+0x4b/0x490 mm/slab.h:737
kmem_cache_alloc_bulk+0x3ba/0x4e0 mm/slub.c:3880
mt_alloc_bulk lib/maple_tree.c:159 [inline]
mas_alloc_nodes+0x449/0x880 lib/maple_tree.c:1301
mas_node_count_gfp lib/maple_tree.c:1361 [inline]
mas_preallocate+0x162/0x3b0 lib/maple_tree.c:5809
__mmap_region mm/mmap.c:2765 [inline]
mmap_region+0xdcb/0x1c50 mm/mmap.c:2916
do_mmap+0x9ce/0x10d0 mm/mmap.c:1436
vm_mmap_pgoff+0x1c1/0x2d0 mm/util.c:520
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: 0033:0x7ffa6cd42242
RSP: 002b:00007ffc99fbc418 EFLAGS: 00000246 ORIG_RAX: 0000000000000009
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007ffa6cd42242
RDX: 0000000000000003 RSI: 0000000000002000 RDI: 0000000000000000
RBP: 0000000000000022 R08: 00000000ffffffff R09: 0000000000000000
R10: 0000000000000022 R11: 0000000000000246 R12: 0000000000002000
R13: 0000000000000000 R14: 0000000000000000 R15: 00007ffa6cd56f50
</TASK>
rcu: rcu_preempt kthread starved for 10502 jiffies! g149289 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:26960 pid:16 ppid:2 flags:0x00004000
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5246 [inline]
__schedule+0x107f/0x4030 kernel/sched/core.c:6563
schedule+0xb9/0x180 kernel/sched/core.c:6639
schedule_timeout+0x184/0x2d0 kernel/time/timer.c:2168
rcu_gp_fqs_loop+0x303/0x1350 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:
CPU: 0 PID: 23811 Comm: syz.2.5258 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:__raw_spin_unlock_irq include/linux/spinlock_api_smp.h:160 [inline]
RIP: 0010:_raw_spin_unlock_irq+0x25/0x40 kernel/locking/spinlock.c:202
Code: 00 00 00 66 90 53 48 89 fb 48 83 c7 18 48 8b 74 24 08 e8 ae 45 2a f7 48 89 df e8 36 0d 2b f7 e8 21 5e 4e f7 fb bf 01 00 00 00 <e8> b6 88 1e f7 65 8b 05 27 3a c8 75 85 c0 74 02 5b c3 e8 34 4e c6
RSP: 0018:ffffc90004e77b98 EFLAGS: 00000282
RAX: ddb69d6f1b99e400 RBX: ffff88807ae3ae40 RCX: ddb69d6f1b99e400
RDX: dffffc0000000000 RSI: ffffffff8a8c17a0 RDI: 0000000000000001
RBP: 0000000000000000 R08: ffff88807ae3ae43 R09: 1ffff1100f5c75c8
R10: dffffc0000000000 R11: ffffed100f5c75c9 R12: 0000000000000021
R13: ffff88807ae3b2d8 R14: dffffc0000000000 R15: 000000001c000004
FS: 00007f6e8a3f06c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000020000006b000 CR3: 0000000074ea8000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
spin_unlock_irq include/linux/spinlock.h:401 [inline]
get_signal+0x114a/0x1340 kernel/signal.c:2883
arch_do_signal_or_restart+0xc4/0x1310 arch/x86/kernel/signal.c:871
exit_to_user_mode_loop+0x70/0x110 kernel/entry/common.c:174
exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:210
__syscall_exit_to_user_mode_work kernel/entry/common.c:292 [inline]
syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:303
do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:82
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f6e8959e017
Code: 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 <0f> 05 48 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89
RSP: 002b:00007f6e8a3f00e8 EFLAGS: 00000246
RAX: 00000000000000ca RBX: 00007f6e89825fa8 RCX: 00007f6e8959e019
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007f6e89825fa8
RBP: 00007f6e89825fa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f6e89826038 R14: 00007ffe47792750 R15: 00007ffe47792838
</TASK>
---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.
syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title
If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)
If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report
If you want to undo deduplication, reply with:
#syz undup
syzbot found the following issue on:
HEAD commit: fb28aa725e05 Linux 6.1.180
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=10c053b9580000
kernel config: https://syzkaller.appspot.com/x/.config?x=31dfefc4a14efea3
dashboard link: https://syzkaller.appspot.com/bug?extid=fcce605c4e72e3a0be8b
compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
Unfortunately, I don't have any reproducer for this issue yet.
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/9a6fe2a54d0f/disk-fb28aa72.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/742b23a1d931/vmlinux-fb28aa72.xz
kernel image: https://storage.googleapis.com/syzbot-assets/b3f257c16d2e/bzImage-fb28aa72.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+fcce60...@syzkaller.appspotmail.com
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P23809/1:b..l
(detected by 0, t=10502 jiffies, g=149289, q=28 ncpus=1)
task:sed state:R running task stack:24752 pid:23809 ppid:23808 flags:0x00004000
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5246 [inline]
__schedule+0x107f/0x4030 kernel/sched/core.c:6563
preempt_schedule_irq+0xbb/0x160 kernel/sched/core.c:6875
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_acquire+0x225/0x4a0 kernel/locking/lockdep.c:5680
Code: f7 84 24 80 00 00 00 00 02 00 00 43 c6 44 3d 04 f8 0f 85 f0 00 00 00 41 f7 c6 00 02 00 00 74 01 fb 48 c7 44 24 60 0e 36 e0 45 <4b> c7 44 3d 00 00 00 00 00 43 c7 44 3d 08 00 00 00 00 65 48 8b 04
RSP: 0018:ffffc90004d9f420 EFLAGS: 00000206
RAX: 0000000000000001 RBX: 0000000000000000 RCX: 555919c126f75300
RDX: 0000000000000000 RSI: ffffffff8a8c2920 RDI: ffffffff8adf5de0
RBP: ffffc90004d9f538 R08: dffffc0000000000 R09: 1ffffffff2162048
R10: dffffc0000000000 R11: fffffbfff2162049 R12: 0000000000000000
R13: 1ffff920009b3e90 R14: 0000000000000246 R15: dffffc0000000000
rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
rcu_read_lock include/linux/rcupdate.h:791 [inline]
is_bpf_text_address+0x43/0x2a0 kernel/bpf/core.c:735
kernel_text_address+0x9c/0xd0 kernel/extable.c:125
__kernel_text_address+0x9/0x30 kernel/extable.c:79
unwind_get_return_address+0x49/0x80 arch/x86/kernel/unwind_orc.c:323
arch_stack_walk+0xf2/0x140 arch/x86/kernel/stacktrace.c:26
stack_trace_save+0xa6/0xf0 kernel/stacktrace.c:122
kasan_save_stack mm/kasan/common.c:46 [inline]
kasan_set_track+0x4b/0x70 mm/kasan/common.c:53
__kasan_slab_alloc+0x6b/0x80 mm/kasan/common.c:329
kasan_slab_alloc include/linux/kasan.h:201 [inline]
slab_post_alloc_hook+0x4b/0x490 mm/slab.h:737
kmem_cache_alloc_bulk+0x3ba/0x4e0 mm/slub.c:3880
mt_alloc_bulk lib/maple_tree.c:159 [inline]
mas_alloc_nodes+0x449/0x880 lib/maple_tree.c:1301
mas_node_count_gfp lib/maple_tree.c:1361 [inline]
mas_preallocate+0x162/0x3b0 lib/maple_tree.c:5809
__mmap_region mm/mmap.c:2765 [inline]
mmap_region+0xdcb/0x1c50 mm/mmap.c:2916
do_mmap+0x9ce/0x10d0 mm/mmap.c:1436
vm_mmap_pgoff+0x1c1/0x2d0 mm/util.c:520
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: 0033:0x7ffa6cd42242
RSP: 002b:00007ffc99fbc418 EFLAGS: 00000246 ORIG_RAX: 0000000000000009
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007ffa6cd42242
RDX: 0000000000000003 RSI: 0000000000002000 RDI: 0000000000000000
RBP: 0000000000000022 R08: 00000000ffffffff R09: 0000000000000000
R10: 0000000000000022 R11: 0000000000000246 R12: 0000000000002000
R13: 0000000000000000 R14: 0000000000000000 R15: 00007ffa6cd56f50
</TASK>
rcu: rcu_preempt kthread starved for 10502 jiffies! g149289 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:26960 pid:16 ppid:2 flags:0x00004000
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5246 [inline]
__schedule+0x107f/0x4030 kernel/sched/core.c:6563
schedule+0xb9/0x180 kernel/sched/core.c:6639
schedule_timeout+0x184/0x2d0 kernel/time/timer.c:2168
rcu_gp_fqs_loop+0x303/0x1350 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:
CPU: 0 PID: 23811 Comm: syz.2.5258 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:__raw_spin_unlock_irq include/linux/spinlock_api_smp.h:160 [inline]
RIP: 0010:_raw_spin_unlock_irq+0x25/0x40 kernel/locking/spinlock.c:202
Code: 00 00 00 66 90 53 48 89 fb 48 83 c7 18 48 8b 74 24 08 e8 ae 45 2a f7 48 89 df e8 36 0d 2b f7 e8 21 5e 4e f7 fb bf 01 00 00 00 <e8> b6 88 1e f7 65 8b 05 27 3a c8 75 85 c0 74 02 5b c3 e8 34 4e c6
RSP: 0018:ffffc90004e77b98 EFLAGS: 00000282
RAX: ddb69d6f1b99e400 RBX: ffff88807ae3ae40 RCX: ddb69d6f1b99e400
RDX: dffffc0000000000 RSI: ffffffff8a8c17a0 RDI: 0000000000000001
RBP: 0000000000000000 R08: ffff88807ae3ae43 R09: 1ffff1100f5c75c8
R10: dffffc0000000000 R11: ffffed100f5c75c9 R12: 0000000000000021
R13: ffff88807ae3b2d8 R14: dffffc0000000000 R15: 000000001c000004
FS: 00007f6e8a3f06c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000020000006b000 CR3: 0000000074ea8000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
spin_unlock_irq include/linux/spinlock.h:401 [inline]
get_signal+0x114a/0x1340 kernel/signal.c:2883
arch_do_signal_or_restart+0xc4/0x1310 arch/x86/kernel/signal.c:871
exit_to_user_mode_loop+0x70/0x110 kernel/entry/common.c:174
exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:210
__syscall_exit_to_user_mode_work kernel/entry/common.c:292 [inline]
syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:303
do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:82
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f6e8959e017
Code: 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 <0f> 05 48 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89
RSP: 002b:00007f6e8a3f00e8 EFLAGS: 00000246
RAX: 00000000000000ca RBX: 00007f6e89825fa8 RCX: 00007f6e8959e019
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007f6e89825fa8
RBP: 00007f6e89825fa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f6e89826038 R14: 00007ffe47792750 R15: 00007ffe47792838
</TASK>
---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.
syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title
If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)
If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report
If you want to undo deduplication, reply with:
#syz undup
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