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Date:   Thu, 09 Sep 2021 17:34:32 -0700
Message-ID: <00000000000071b5b105cb994728@google.com>
Subject: [syzbot] kernel panic: panic_on_warn set (3)
From:   syzbot <syzbot+8d41ad9c88279d71f7c9@syzkaller.appspotmail.com>
To:     akpm@linux-foundation.org, dvyukov@google.com, elver@google.com,
        glider@google.com, kasan-dev@googlegroups.com,
        linux-kernel@vger.kernel.org, linux-mm@kvack.org,
        syzkaller-bugs@googlegroups.com
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Hello,

syzbot found the following issue on:

HEAD commit:    ac08b1c68d1b Merge tag 'pci-v5.15-changes' of git://git.ke..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=16144a63300000
kernel config:  https://syzkaller.appspot.com/x/.config?x=16e23f04679ec35e
dashboard link: https://syzkaller.appspot.com/bug?extid=8d41ad9c88279d71f7c9
compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.1
userspace arch: i386
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=136aedb5300000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+8d41ad9c88279d71f7c9@syzkaller.appspotmail.com

 handle drivers/base/devtmpfs.c:382 [inline]
 devtmpfs_work_loop drivers/base/devtmpfs.c:395 [inline]
 devtmpfsd+0x1b9/0x2a3 drivers/base/devtmpfs.c:437
 kthread+0x3e5/0x4d0 kernel/kthread.c:319
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
==================================================================
Kernel panic - not syncing: panic_on_warn set ...
CPU: 0 PID: 22 Comm: kdevtmpfs Not tainted 5.14.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:105
 panic+0x2b0/0x6dd kernel/panic.c:232
 kfence_report_error.cold+0x304/0xa56 mm/kfence/report.c:264
 kfence_handle_page_fault+0x203/0x630 mm/kfence/core.c:880
 page_fault_oops+0x1c5/0x6b0 arch/x86/mm/fault.c:686
 kernelmode_fixup_or_oops+0x219/0x280 arch/x86/mm/fault.c:755
 __bad_area_nosemaphore+0x36d/0x400 arch/x86/mm/fault.c:801
 do_kern_addr_fault+0x5b/0x70 arch/x86/mm/fault.c:1200
 handle_page_fault arch/x86/mm/fault.c:1473 [inline]
 exc_page_fault+0x155/0x180 arch/x86/mm/fault.c:1531
 asm_exc_page_fault+0x1e/0x30 arch/x86/include/asm/idtentry.h:568
RIP: 0010:kvm_fastop_exception+0xf6a/0x1058
Code: d3 ed e9 ef d4 6e f8 49 8d 0e 48 83 e1 f8 4c 8b 21 41 8d 0e 83 e1 07 c1 e1 03 49 d3 ec e9 45 e2 6e f8 49 8d 4d 00 48 83 e1 f8 <4c> 8b 21 41 8d 4d 00 83 e1 07 c1 e1 03 49 d3 ec e9 35 ec 6e f8 bd
RSP: 0018:ffffc90000dcfae8 EFLAGS: 00010282
RAX: 0000003361736376 RBX: ffff88806f1e3068 RCX: ffff88823bd14020
RDX: ffffed100de3c614 RSI: 0000000000000005 RDI: 0000000000000007
RBP: 0000000000000005 R08: 0000000000000000 R09: ffff88806f1e3098
R10: ffffed100de3c613 R11: 0000000000000000 R12: ffff88823bd14020
R13: ffff88823bd14020 R14: ffff88806f1e3098 R15: dffffc0000000000
 d_lookup+0xd8/0x170 fs/dcache.c:2370
 lookup_dcache+0x1e/0x130 fs/namei.c:1520
 __lookup_hash+0x29/0x180 fs/namei.c:1543
 kern_path_locked+0x17e/0x320 fs/namei.c:2567
 handle_remove+0xa2/0x5fe drivers/base/devtmpfs.c:312
 handle drivers/base/devtmpfs.c:382 [inline]
 devtmpfs_work_loop drivers/base/devtmpfs.c:395 [inline]
 devtmpfsd+0x1b9/0x2a3 drivers/base/devtmpfs.c:437
 kthread+0x3e5/0x4d0 kernel/kthread.c:319
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
Kernel Offset: disabled
----------------
Code disassembly (best guess):
   0:	d3 ed                	shr    %cl,%ebp
   2:	e9 ef d4 6e f8       	jmpq   0xf86ed4f6
   7:	49 8d 0e             	lea    (%r14),%rcx
   a:	48 83 e1 f8          	and    $0xfffffffffffffff8,%rcx
   e:	4c 8b 21             	mov    (%rcx),%r12
  11:	41 8d 0e             	lea    (%r14),%ecx
  14:	83 e1 07             	and    $0x7,%ecx
  17:	c1 e1 03             	shl    $0x3,%ecx
  1a:	49 d3 ec             	shr    %cl,%r12
  1d:	e9 45 e2 6e f8       	jmpq   0xf86ee267
  22:	49 8d 4d 00          	lea    0x0(%r13),%rcx
  26:	48 83 e1 f8          	and    $0xfffffffffffffff8,%rcx
* 2a:	4c 8b 21             	mov    (%rcx),%r12 <-- trapping instruction
  2d:	41 8d 4d 00          	lea    0x0(%r13),%ecx
  31:	83 e1 07             	and    $0x7,%ecx
  34:	c1 e1 03             	shl    $0x3,%ecx
  37:	49 d3 ec             	shr    %cl,%r12
  3a:	e9 35 ec 6e f8       	jmpq   0xf86eec74
  3f:	bd                   	.byte 0xbd


---
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