[v6.1] INFO: rcu detected stall in validate_mm (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 0cbb5f65e52f Linux 6.1.128
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=1089b764580000
kernel config: https://syzkaller.appspot.com/x/.config?x=ddc0722618a3964e
dashboard link: https://syzkaller.appspot.com/bug?extid=022b50cd692aa01556aa
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/c6d849a518b0/disk-0cbb5f65.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/76ad82aaf432/vmlinux-0cbb5f65.xz
kernel image: https://storage.googleapis.com/syzbot-assets/5d4b74f07bf4/bzImage-0cbb5f65.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+022b50...@syzkaller.appspotmail.com

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P5475/1:b..l
(detected by 0, t=10502 jiffies, g=18841, q=606 ncpus=2)
task:rm state:R running task stack:23176 pid:5475 ppid:5430 flags:0x00004000
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5241 [inline]
__schedule+0x143f/0x4570 kernel/sched/core.c:6558
preempt_schedule_irq+0xf7/0x1c0 kernel/sched/core.c:6870
irqentry_exit+0x53/0x80 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+0x1c/0x180 kernel/locking/lockdep.c:5690
Code: fd ff ff 66 2e 0f 1f 84 00 00 00 00 00 90 55 41 57 41 56 41 55 41 54 53 48 83 ec 10 65 48 8b 04 25 28 00 00 00 48 89 44 24 08 <bd> ff ff ff ff 83 3d 4c 86 e8 03 00 0f 84 00 01 00 00 65 8b 05 8b
RSP: 0018:ffffc900060ef5b8 EFLAGS: 00000286
RAX: f0767c7359523f00 RBX: 0000000000000300 RCX: dffffc0000000000
RDX: ffff88807abdb480 RSI: 00000000ffffffff RDI: ffff88807abdb5d8
RBP: ffffc900060ef7f0 R08: ffffffff8aa9a299 R09: 0000000000000003
R10: ffffffffffffffff R11: dffffc0000000001 R12: ffff888053f38c58
R13: ffff888053f38e0c R14: 0000000000000001 R15: ffffc900060ef758
mt_slot lib/maple_tree.c:814 [inline]
mas_slot lib/maple_tree.c:847 [inline]
mas_validate_parent_slot lib/maple_tree.c:7058 [inline]
mt_validate+0x1401/0x5ad0 lib/maple_tree.c:7247
validate_mm_mt+0x165/0x670 mm/mmap.c:294
validate_mm+0x16e/0x380 mm/mmap.c:331
mmap_region+0x1556/0x2660 mm/mmap.c:2910
do_mmap+0x8c5/0xf60 mm/mmap.c:1424
vm_mmap_pgoff+0x1ca/0x2d0 mm/util.c:520
ksys_mmap_pgoff+0x4f5/0x6d0 mm/mmap.c:1470
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fdf63f3eb74
RSP: 002b:00007ffe9c4482b8 EFLAGS: 00000246 ORIG_RAX: 0000000000000009
RAX: ffffffffffffffda RBX: 00007ffe9c4482f8 RCX: 00007fdf63f3eb74
RDX: 0000000000000005 RSI: 000000000002c000 RDI: 00007fdf63c23000
RBP: 00007ffe9c448650 R08: 0000000000000003 R09: 0000000000002000
R10: 0000000000000812 R11: 0000000000000246 R12: 00007fdf63f22570
R13: 00007ffe9c4486d8 R14: 0000000000001fd8 R15: 0000000000000000
</TASK>
rcu: rcu_preempt kthread starved for 7930 jiffies! g18841 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:25528 pid:16 ppid:2 flags:0x00004000
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5241 [inline]
__schedule+0x143f/0x4570 kernel/sched/core.c:6558
schedule+0xbf/0x180 kernel/sched/core.c:6634
schedule_timeout+0x1b9/0x300 kernel/time/timer.c:1965
rcu_gp_fqs_loop+0x2d2/0x1150 kernel/rcu/tree.c:1706
rcu_gp_kthread+0xa3/0x3b0 kernel/rcu/tree.c:1905
kthread+0x28d/0x320 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 6.1.128-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 12/27/2024
RIP: 0010:native_save_fl arch/x86/include/asm/irqflags.h:22 [inline]
RIP: 0010:arch_local_save_flags arch/x86/include/asm/irqflags.h:70 [inline]
RIP: 0010:arch_irqs_disabled arch/x86/include/asm/irqflags.h:130 [inline]
RIP: 0010:acpi_safe_halt drivers/acpi/processor_idle.c:112 [inline]
RIP: 0010:acpi_idle_do_entry+0x10f/0x340 drivers/acpi/processor_idle.c:567
Code: 6a cd f6 48 83 e3 08 0f 85 0b 01 00 00 4c 8d 74 24 20 e8 b4 26 d4 f6 0f 1f 44 00 00 e8 1a 66 cd f6 0f 00 2d d3 67 ab 00 fb f4 <4c> 89 f3 48 c1 eb 03 42 80 3c 3b 00 74 08 4c 89 f7 e8 6b f9 24 f7
RSP: 0018:ffffffff8d007b20 EFLAGS: 000002d3
RAX: ffffffff8abd3686 RBX: 0000000000000000 RCX: ffffffff8d0bd8c0
RDX: 0000000000000000 RSI: ffffffff8b0c0340 RDI: ffffffff8b5e6980
RBP: ffffffff8d007bb0 R08: ffffffff8abd3668 R09: fffffbfff1a17b19
R10: 0000000000000000 R11: dffffc0000000001 R12: 1ffffffff1a00f64
R13: ffff888019f5f004 R14: ffffffff8d007b40 R15: dffffc0000000000
FS: 0000000000000000(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fd56a7dd866 CR3: 000000007bef9000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<IRQ>
</IRQ>
<TASK>
acpi_idle_enter+0x352/0x4f0 drivers/acpi/processor_idle.c:704
cpuidle_enter_state+0x516/0xf80 drivers/cpuidle/cpuidle.c:239
cpuidle_enter+0x59/0x90 drivers/cpuidle/cpuidle.c:356
call_cpuidle kernel/sched/idle.c:155 [inline]
cpuidle_idle_call kernel/sched/idle.c:236 [inline]
do_idle+0x3ce/0x680 kernel/sched/idle.c:303
cpu_startup_entry+0x3d/0x60 kernel/sched/idle.c:401
rest_init+0x2da/0x300 init/main.c:733
arch_call_rest_init+0xa/0xa init/main.c:893
start_kernel+0x496/0x53f init/main.c:1140
secondary_startup_64_no_verify+0xcf/0xdb
</TASK>


---
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[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit: 50cbba13faa2 Linux 6.1.159
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=158221fc580000
kernel config: https://syzkaller.appspot.com/x/.config?x=6a5cbd268406bf43
dashboard link: https://syzkaller.appspot.com/bug?extid=022b50cd692aa01556aa
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1341019a580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1372883a580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/50ceb00b1b39/disk-50cbba13.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/ebb8883b9a29/vmlinux-50cbba13.xz
kernel image: https://storage.googleapis.com/syzbot-assets/7edc2a795f03/bzImage-50cbba13.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/8aa18eda83ad/mount_8.gz
fsck result: failed (log: https://syzkaller.appspot.com/x/fsck.log?x=1541019a580000)

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+022b50...@syzkaller.appspotmail.com

rcu: INFO: rcu_preempt detected expedited stalls on CPUs/tasks: { 1-...D } 2672 jiffies s: 3041 root: 0x2/.
rcu: blocking rcu_node structures (internal RCU debug):
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 4377 Comm: udevd Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:_test_bit include/asm-generic/bitops/instrumented-non-atomic.h:141 [inline]
RIP: 0010:__lock_acquire+0xdb4/0x7c50 kernel/locking/lockdep.c:5019
Code: ff df 42 0f b6 04 00 84 c0 0f 85 a6 5b 00 00 83 3d 40 dc 39 15 00 48 8b 84 24 a8 00 00 00 75 34 48 63 d8 48 89 d8 48 c1 e8 06 <48> 8d 3c c5 40 82 8c 90 be 08 00 00 00 e8 8a fd 6d 00 49 b8 00 00
RSP: 0018:ffffc900001e08e0 EFLAGS: 00000047
RAX: 0000000000000000 RBX: 000000000000002c RCX: ffffffff969cf103
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff908c8240
RBP: ffffc900001e0b30 R08: dffffc0000000000 R09: fffffbfff2119049
R10: fffffbfff2119049 R11: 1ffffffff2119048 R12: ffff888025770000
R13: ffff888025770b02 R14: ffff888025770b30 R15: ffff888025770b50
FS: 00007fcd0cea2880(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000

CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033

CR2: 00007fcd0cea0000 CR3: 0000000029661000 CR4: 00000000003506e0

DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<IRQ>

lock_acquire+0x1b4/0x490 kernel/locking/lockdep.c:5662
rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
rcu_read_lock include/linux/rcupdate.h:791 [inline]
advance_sched+0x6e8/0x970 net/sched/sch_taprio.c:753
__run_hrtimer kernel/time/hrtimer.c:1747 [inline]
__hrtimer_run_queues+0x554/0xd60 kernel/time/hrtimer.c:1811
hrtimer_interrupt+0x3c5/0x9c0 kernel/time/hrtimer.c:1873
local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1107 [inline]
__sysvec_apic_timer_interrupt+0x153/0x5a0 arch/x86/kernel/apic/apic.c:1124
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1118 [inline]
sysvec_apic_timer_interrupt+0x9b/0xc0 arch/x86/kernel/apic/apic.c:1118
</IRQ>
<TASK>
asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691
RIP: 0010:vma_start_pgoff mm/interval_tree.c:15 [inline]
RIP: 0010:avc_start_pgoff mm/interval_tree.c:63 [inline]
RIP: 0010:anon_vma_interval_tree_verify+0x50/0x140 mm/interval_tree.c:108
Code: 42 80 3c 20 00 74 05 e8 8e 28 16 00 4c 8b 73 40 49 89 dd 49 c1 ed 03 43 80 7c 25 00 00 74 08 48 89 df e8 73 28 16 00 4c 8b 3b <49> 83 c7 68 4c 89 f8 48 c1 e8 03 42 80 3c 20 00 74 08 4c 89 ff e8
RSP: 0018:ffffc900033979b0 EFLAGS: 00000246
RAX: 1ffff1100fc3994a RBX: ffff88807e1cca10 RCX: ffff888025770000
RDX: 0000000000000000 RSI: 0000000000000035 RDI: ffff88807e1cca50
RBP: ffffc90003397ad0 R08: dffffc0000000000 R09: ffffed1005c880ad
R10: ffffed1005c880ad R11: 1ffff11005c880ac R12: dffffc0000000000
R13: 1ffff1100fc39942 R14: 0000000000000035 R15: ffff888027b84a20
validate_mm+0x175/0x2b0 mm/mmap.c:342
mmap_region+0x780/0x1c70 mm/mmap.c:2922
do_mmap+0x958/0xfd0 mm/mmap.c:1436
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: 0033:0x7fcd0c71d822
Code: 00 00 00 0f 1f 44 00 00 41 f7 c1 ff 0f 00 00 75 27 55 89 cd 53 48 89 fb 48 85 ff 74 3b 41 89 ea 48 89 df b8 09 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 76 5b 5d c3 0f 1f 00 48 8b 05 a1 35 0d 00 64
RSP: 002b:00007fff19b5dfd8 EFLAGS: 00000246 ORIG_RAX: 0000000000000009
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fcd0c71d822
RDX: 0000000000000003 RSI: 0000000000000200 RDI: 0000000000000000
RBP: 0000000000000022 R08: 00000000ffffffff R09: 0000000000000000
R10: 0000000000000022 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000200 R14: 0000558a0388e0b0 R15: 0000000000003e00
</TASK>


---
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