Message-ID: <691019d5.a70a0220.22f260.0098.GAE@google.com>
Date: Sat, 08 Nov 2025 20:34:29 -0800
From: syzbot <syzbot+b492b1871577c9dcaebc@...kaller.appspotmail.com>
To: bp@...en8.de, dave.hansen@...ux.intel.com, hpa@...or.com, 
	linux-kernel@...r.kernel.org, mingo@...hat.com, 
	syzkaller-bugs@...glegroups.com, tglx@...utronix.de, x86@...nel.org
Subject: [syzbot] [kernel?] WARNING in _prb_read_valid

Hello,

syzbot found the following issue on:

HEAD commit:    17490bd0527f Add linux-next specific files for 20251104
git tree:       linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=100f2114580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=99a6439adcb87a9e
dashboard link: https://syzkaller.appspot.com/bug?extid=b492b1871577c9dcaebc
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/9b67f1f748d3/disk-17490bd0.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/2c8bd981892f/vmlinux-17490bd0.xz
kernel image: https://storage.googleapis.com/syzbot-assets/83c27f8467c8/bzImage-17490bd0.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+b492b1871577c9dcaebc@...kaller.appspotmail.com

------------[ cut here ]------------
WARNING: mm/slub.c:6756 at free_large_kmalloc+0x15c/0x1f0 mm/slub.c:6756, CPU#0: syz-executor/5833
Modules linked in:
CPU: 0 UID: 0 PID: 5833 Comm: syz-executor Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
RIP: 0010:free_large_kmalloc+0x15c/0x1f0 mm/slub.c:6756
Code: 44 89 f6 e8 f6 d0 fc ff 65 48 8b 05 4e 43 58 10 48 3b 44 24 08 75 57 48 83 c4 10 5b 41 5c 41 5e 41 5f 5d c3 cc cc cc cc cc 90 <0f> 0b 90 65 48 8b 05 29 43 58 10 48 3b 44 24 08 75 32 48 89 df 48
RSP: 0018:ffffc9000425fc88 EFLAGS: 00010206
RAX: 00000000ff000000 RBX: ffffea0000389300 RCX: ffffea0000389308
RDX: 0000000000000000 RSI: ffffffff8e24c120 RDI: ffffea0000389300
RBP: 1ffff1100457bd43 R08: ffffffff8f7d7d77 R09: 1ffffffff1efafae
------------[ cut here ]------------
WARNING: kernel/printk/printk_ringbuffer.c:1278 at get_data+0x48a/0x840 kernel/printk/printk_ringbuffer.c:1278, CPU#0: syz-executor/5833
Modules linked in:
CPU: 0 UID: 0 PID: 5833 Comm: syz-executor Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
RIP: 0010:get_data+0x48a/0x840 kernel/printk/printk_ringbuffer.c:1278
Code: 83 c4 f8 48 b8 00 00 00 00 00 fc ff df 41 0f b6 04 07 84 c0 0f 85 ee 01 00 00 44 89 65 00 49 83 c5 08 eb 13 e8 57 1a 1f 00 90 <0f> 0b 90 eb 05 e8 4c 1a 1f 00 45 31 ed 4c 89 e8 48 83 c4 28 5b 41
RSP: 0018:ffffc9000425f220 EFLAGS: 00010293
RAX: ffffffff81a1f239 RBX: 00003fffffffffff RCX: ffff88802b5f9e80
RDX: 0000000000000000 RSI: 00003fffffffffff RDI: 0000000000000000
RBP: 0000000000000012 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000012
R13: 0000000000000000 R14: ffffc9000425f368 R15: 1ffffffff1bca682
FS:  0000555588454500(0000) GS:ffff888125ed8000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffc9e6a1b78 CR3: 0000000064e40000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 copy_data kernel/printk/printk_ringbuffer.c:1857 [inline]
 prb_read kernel/printk/printk_ringbuffer.c:1966 [inline]
 _prb_read_valid+0x672/0xa90 kernel/printk/printk_ringbuffer.c:2143
 prb_read_valid+0x3c/0x60 kernel/printk/printk_ringbuffer.c:2215
 printk_get_next_message+0x15c/0x7b0 kernel/printk/printk.c:2978
 console_emit_next_record kernel/printk/printk.c:3062 [inline]
 console_flush_one_record kernel/printk/printk.c:3194 [inline]
 console_flush_all+0x4cc/0xb10 kernel/printk/printk.c:3268
 __console_flush_and_unlock kernel/printk/printk.c:3298 [inline]
 console_unlock+0xbb/0x190 kernel/printk/printk.c:3338
 vprintk_emit+0x4c5/0x590 kernel/printk/printk.c:2423
 _printk+0xcf/0x120 kernel/printk/printk.c:2448
 __show_regs+0x225/0x620 arch/x86/kernel/process_64.c:90
 show_regs+0x36/0x70 arch/x86/kernel/dumpstack.c:483
 __warn+0x182/0x4c0 kernel/panic.c:899
 __report_bug lib/bug.c:195 [inline]
 report_bug+0x2be/0x4f0 lib/bug.c:215
 handle_bug+0x84/0x160 arch/x86/kernel/traps.c:338
 exc_invalid_op+0x1a/0x50 arch/x86/kernel/traps.c:392
 asm_exc_invalid_op+0x1a/0x20 arch/x86/include/asm/idtentry.h:616
RIP: 0010:free_large_kmalloc+0x15c/0x1f0 mm/slub.c:6756
Code: 44 89 f6 e8 f6 d0 fc ff 65 48 8b 05 4e 43 58 10 48 3b 44 24 08 75 57 48 83 c4 10 5b 41 5c 41 5e 41 5f 5d c3 cc cc cc cc cc 90 <0f> 0b 90 65 48 8b 05 29 43 58 10 48 3b 44 24 08 75 32 48 89 df 48
RSP: 0018:ffffc9000425fc88 EFLAGS: 00010206
RAX: 00000000ff000000 RBX: ffffea0000389300 RCX: ffffea0000389308
RDX: 0000000000000000 RSI: ffffffff8e24c120 RDI: ffffea0000389300
RBP: 1ffff1100457bd43 R08: ffffffff8f7d7d77 R09: 1ffffffff1efafae
R10: dffffc0000000000 R11: fffffbfff1efafaf R12: 1ffff1100457bd36
R13: dffffc0000000000 R14: ffff888022bde9b0 R15: ffff88803293a448
 ntfs_put_super+0x15b/0x1b0 fs/ntfs3/super.c:708
 generic_shutdown_super+0x135/0x2c0 fs/super.c:643
 kill_block_super+0x44/0x90 fs/super.c:1723
 ntfs3_kill_sb+0x44/0x1b0 fs/ntfs3/super.c:1850
 deactivate_locked_super+0xbc/0x130 fs/super.c:474
 cleanup_mnt+0x425/0x4c0 fs/namespace.c:1317
 task_work_run+0x1d4/0x260 kernel/task_work.c:233
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 exit_to_user_mode_loop+0xe9/0x130 kernel/entry/common.c:43
 exit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [inline]
 syscall_exit_to_user_mode_work include/linux/entry-common.h:175 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:210 [inline]
 do_syscall_64+0x2cd/0xfa0 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fd6175909f7
Code: a8 ff ff ff f7 d8 64 89 01 48 83 c8 ff c3 0f 1f 44 00 00 31 f6 e9 09 00 00 00 66 0f 1f 84 00 00 00 00 00 b8 a6 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 01 c3 48 c7 c2 a8 ff ff ff f7 d8 64 89 02 b8
RSP: 002b:00007ffda216ea18 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 00007fd617611d7d RCX: 00007fd6175909f7
RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007ffda216ead0
RBP: 00007ffda216ead0 R08: 0000000000000000 R09: 0000000000000000
R10: 00000000ffffffff R11: 0000000000000246 R12: 00007ffda216fb60
R13: 00007fd617611d7d R14: 0000000000024391 R15: 00007ffda216fba0
 </TASK>


---
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