[v5.15] INFO: rcu detected stall in mremap

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: cc5ec8769306 Linux 5.15.196
git tree: linux-5.15.y
console output: https://syzkaller.appspot.com/x/log.txt?x=113d297c580000
kernel config: https://syzkaller.appspot.com/x/.config?x=e1bb6d24ef2164eb
dashboard link: https://syzkaller.appspot.com/bug?extid=adcc25a83d9d0af109aa
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/c71c660545b2/disk-cc5ec876.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/4f011826cca6/vmlinux-cc5ec876.xz
kernel image: https://storage.googleapis.com/syzbot-assets/8ccd1a2c3f8c/bzImage-cc5ec876.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+adcc25...@syzkaller.appspotmail.com

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 1-...!: (0 ticks this GP) idle=07b/1/0x4000000000000000 softirq=50445/50448 fqs=2
(detected by 0, t=10502 jiffies, g=58145, q=290)
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 16889 Comm: syz.7.5137 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
RIP: 0010:lock_is_held_type+0x1/0x190 kernel/locking/lockdep.c:5651
Code: c0 03 00 75 d6 48 c7 c7 00 1b 0b 8a 48 c7 c6 40 1b 0b 8a e8 c1 37 f5 ff 0f 0b eb bf e8 98 fd ff ff 0f 1f 84 00 00 00 00 00 55 <41> 57 41 56 41 55 41 54 53 48 83 ec 10 65 48 8b 04 25 28 00 00 00
RSP: 0018:ffffc90000dd0c70 EFLAGS: 00000002
RAX: ffffffff880972ff RBX: 0000000000000001 RCX: ffff888023b09dc0
RDX: 0000000000010000 RSI: 00000000ffffffff RDI: ffff888142fdab00
RBP: ffff888142fdab40 R08: 0000000000000004 R09: 0000000000000003
R10: fffff520001ba180 R11: 1ffff920001ba180 R12: ffff888142fda800
R13: dffffc0000000000 R14: ffff888022189780 R15: ffff88801dcd4c00
FS: 00007f05f58966c0(0000) GS:ffff8880b9100000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005560f24fb168 CR3: 000000006493c000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<IRQ>
lock_is_held include/linux/lockdep.h:287 [inline]
advance_sched+0x141/0x940 net/sched/sch_taprio.c:721
__run_hrtimer kernel/time/hrtimer.c:1685 [inline]
__hrtimer_run_queues+0x53d/0xc40 kernel/time/hrtimer.c:1749
hrtimer_interrupt+0x3bb/0x8d0 kernel/time/hrtimer.c:1811
local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1097 [inline]
__sysvec_apic_timer_interrupt+0x137/0x4a0 arch/x86/kernel/apic/apic.c:1114
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline]
sysvec_apic_timer_interrupt+0x9b/0xc0 arch/x86/kernel/apic/apic.c:1108
</IRQ>
<TASK>
asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:mark_page_accessed+0x1ec/0x12b0 mm/swap.c:408
Code: ff 0f 84 29 0f 00 00 4d 85 e4 0f 85 03 0d 00 00 e8 a9 52 d7 ff 49 89 de 4c 89 f7 be 08 00 00 00 e8 59 bc 1b 00 f0 41 80 0e 02 <e9> 82 0a 00 00 4d 85 ed 0f 85 ce 0c 00 00 e8 81 52 d7 ff 49 89 df
RSP: 0018:ffffc90003f2f9b8 EFLAGS: 00000206
RAX: ffffffff81a07901 RBX: ffffea00010ff900 RCX: ffffffff81a07977
RDX: 0000000000000001 RSI: 0000000000000008 RDI: ffffea00010ff900
RBP: dffffc0000000000 R08: dffffc0000000000 R09: fffff9400021ff21
R10: fffff9400021ff21 R11: 1ffffd400021ff20 R12: 0000000000000000
R13: 0000000000000000 R14: ffffea00010ff900 R15: 00fff00000280004
follow_page_pte+0x912/0xc20 mm/gup.c:610
follow_pmd_mask mm/gup.c:-1 [inline]
follow_pud_mask mm/gup.c:788 [inline]
follow_p4d_mask mm/gup.c:814 [inline]
follow_page_mask+0xa6e/0x12d0 mm/gup.c:873
__get_user_pages+0xdb5/0x11c0 mm/gup.c:1195
populate_vma_page_range+0x213/0x290 mm/gup.c:1529
__mm_populate+0x26f/0x3a0 mm/gup.c:1638
mm_populate include/linux/mm.h:2646 [inline]
__do_sys_mremap mm/mremap.c:1049 [inline]
__se_sys_mremap+0x5a7/0x990 mm/mremap.c:898
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f05f762f6c9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f05f5896038 EFLAGS: 00000246 ORIG_RAX: 0000000000000019
RAX: ffffffffffffffda RBX: 00007f05f7885fa0 RCX: 00007f05f762f6c9
RDX: 0000000005000000 RSI: 0000000000002000 RDI: 0000200000ff5000
RBP: 00007f05f76b1f91 R08: 0000200000ffd000 R09: 0000000000000000
R10: 0000000000000003 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f05f7886038 R14: 00007f05f7885fa0 R15: 00007ffd4d7643c8
</TASK>
rcu: rcu_preempt kthread starved for 10490 jiffies! g58145 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:28064 pid: 15 ppid: 2 flags:0x00004000
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5049 [inline]
__schedule+0x11bb/0x4390 kernel/sched/core.c:6395
schedule+0x11b/0x1e0 kernel/sched/core.c:6478
schedule_timeout+0x15c/0x280 kernel/time/timer.c:1914
rcu_gp_fqs_loop+0x29e/0x11b0 kernel/rcu/tree.c:1972
rcu_gp_kthread+0x98/0x350 kernel/rcu/tree.c:2145
kthread+0x436/0x520 kernel/kthread.c:334
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
</TASK>
rcu: Stack dump where RCU GP kthread last ran:
NMI backtrace for cpu 0
CPU: 0 PID: 16903 Comm: syz.3.5143 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
Call Trace:
<IRQ>
dump_stack_lvl+0x168/0x230 lib/dump_stack.c:106
nmi_cpu_backtrace+0x397/0x3d0 lib/nmi_backtrace.c:111
nmi_trigger_cpumask_backtrace+0x163/0x280 lib/nmi_backtrace.c:62
trigger_single_cpu_backtrace include/linux/nmi.h:166 [inline]
rcu_check_gp_kthread_starvation+0x1cd/0x250 kernel/rcu/tree_stall.h:487
print_other_cpu_stall+0x10c8/0x1220 kernel/rcu/tree_stall.h:592
check_cpu_stall kernel/rcu/tree_stall.h:745 [inline]
rcu_pending kernel/rcu/tree.c:3936 [inline]
rcu_sched_clock_irq+0x831/0x1110 kernel/rcu/tree.c:2619
update_process_times+0x193/0x200 kernel/time/timer.c:1818
tick_sched_handle kernel/time/tick-sched.c:254 [inline]
tick_sched_timer+0x37d/0x560 kernel/time/tick-sched.c:1473
__run_hrtimer kernel/time/hrtimer.c:1685 [inline]
__hrtimer_run_queues+0x4fe/0xc40 kernel/time/hrtimer.c:1749
hrtimer_interrupt+0x3bb/0x8d0 kernel/time/hrtimer.c:1811
local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1097 [inline]
__sysvec_apic_timer_interrupt+0x137/0x4a0 arch/x86/kernel/apic/apic.c:1114
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline]
sysvec_apic_timer_interrupt+0x9b/0xc0 arch/x86/kernel/apic/apic.c:1108
</IRQ>
<TASK>
asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:csd_lock_wait kernel/smp.c:440 [inline]
RIP: 0010:smp_call_function_many_cond+0xb88/0xd70 kernel/smp.c:969
Code: b6 44 05 00 84 c0 0f 85 9d 00 00 00 41 8b 1c 24 89 de 83 e6 01 31 ff e8 66 49 0b 00 83 e3 01 75 07 e8 fc 45 0b 00 eb 43 f3 90 <48> b8 00 00 00 00 00 fc ff df 41 0f b6 44 05 00 84 c0 75 11 41 f7
RSP: 0018:ffffc900032ef900 EFLAGS: 00000246
RAX: ffffffff816c863b RBX: 0000000000000001 RCX: 0000000000080000
RDX: ffffc9000d101000 RSI: 000000000007ffff RDI: 0000000000080000
RBP: ffffc900032efa40 R08: dffffc0000000000 R09: fffffbfff1ff7c2e
R10: fffffbfff1ff7c2e R11: 1ffffffff1ff7c2d R12: ffff8880b91405c8
R13: 1ffff110172280b9 R14: ffff8880b903b3c0 R15: 0000000000000001
on_each_cpu_cond_mask+0x3b/0x80 kernel/smp.c:1134
kill_bdev block/bdev.c:76 [inline]
set_blocksize+0x2eb/0x370 block/bdev.c:157
sb_set_blocksize block/bdev.c:166 [inline]
sb_min_blocksize+0xdc/0x1a0 block/bdev.c:182
ext4_fill_super+0x642/0x9a60 fs/ext4/super.c:3942
mount_bdev+0x287/0x3c0 fs/super.c:1400
legacy_get_tree+0xe6/0x180 fs/fs_context.c:611
vfs_get_tree+0x88/0x270 fs/super.c:1530
do_new_mount+0x24a/0xa40 fs/namespace.c:3034
do_mount fs/namespace.c:3377 [inline]
__do_sys_mount fs/namespace.c:3585 [inline]
__se_sys_mount+0x2d6/0x3c0 fs/namespace.c:3562
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f998087ee6a
Code: d8 64 89 02 48 c7 c0 ff ff ff ff eb a6 e8 de 1a 00 00 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 49 89 ca b8 a5 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f997eae3e68 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007f997eae3ef0 RCX: 00007f998087ee6a
RDX: 0000200000000100 RSI: 0000200000000500 RDI: 00007f997eae3eb0
RBP: 0000200000000100 R08: 00007f997eae3ef0 R09: 0000000002008002
R10: 0000000002008002 R11: 0000000000000246 R12: 0000200000000500
R13: 00007f997eae3eb0 R14: 0000000000000549 R15: 0000200000000080
</TASK>


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