Re: linux-next test error: BUG: using smp_processor_id() in preemptible [ADDR] code: systemd-rfkill/6728

From: Eric Biggers <ebiggers@kernel.org>
To: Ritesh Harjani <riteshh@linux.ibm.com>
Cc: adilger.kernel@dilger.ca, linux-ext4@vger.kernel.org,
	linux-kernel@vger.kernel.org, linux-next@vger.kernel.org,
	sfr@canb.auug.org.au, syzkaller-bugs@googlegroups.com,
	tytso@mit.edu,
	syzbot <syzbot+aed048f49c59eb997737@syzkaller.appspotmail.com>
Subject: Re: linux-next test error: BUG: using smp_processor_id() in preemptible [ADDR] code: systemd-rfkill/6728
Date: Thu, 4 Jun 2020 21:02:20 -0700	[thread overview]
Message-ID: <20200605040220.GB2667@sol.localdomain> (raw)
In-Reply-To: <000000000000a7be4a05a74ca69a@google.com>

Introduced by:

commit 42f56b7a4a7db127a9d281da584152dc3d525d25
Author: Ritesh Harjani <riteshh@linux.ibm.com>
Date:   Wed May 20 12:10:34 2020 +0530

    ext4: mballoc: introduce pcpu seqcnt for freeing PA to improve ENOSPC handling

On Thu, Jun 04, 2020 at 07:02:18PM -0700, syzbot wrote:
> Hello,
> 
> syzbot found the following crash on:
> 
> HEAD commit:    0e21d462 Add linux-next specific files for 20200602
> git tree:       linux-next
> console output: https://syzkaller.appspot.com/x/log.txt?x=10461661100000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=ecc1aef35f550ee3
> dashboard link: https://syzkaller.appspot.com/bug?extid=aed048f49c59eb997737
> compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
> 
> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: syzbot+aed048f49c59eb997737@syzkaller.appspotmail.com
> 
> BUG: using smp_processor_id() in preemptible [00000000] code: systemd-rfkill/6728
> caller is ext4_mb_new_blocks+0xa4d/0x3b70 fs/ext4/mballoc.c:4711
> CPU: 1 PID: 6728 Comm: systemd-rfkill Not tainted 5.7.0-next-20200602-syzkaller #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> Call Trace:
>  __dump_stack lib/dump_stack.c:77 [inline]
>  dump_stack+0x18f/0x20d lib/dump_stack.c:118
>  check_preemption_disabled+0x20d/0x220 lib/smp_processor_id.c:48
>  ext4_mb_new_blocks+0xa4d/0x3b70 fs/ext4/mballoc.c:4711
>  ext4_ext_map_blocks+0x201b/0x33e0 fs/ext4/extents.c:4244
>  ext4_map_blocks+0x4cb/0x1640 fs/ext4/inode.c:626
>  ext4_getblk+0xad/0x520 fs/ext4/inode.c:833
>  ext4_bread+0x7c/0x380 fs/ext4/inode.c:883
>  ext4_append+0x153/0x360 fs/ext4/namei.c:67
>  ext4_init_new_dir fs/ext4/namei.c:2757 [inline]
>  ext4_mkdir+0x5e0/0xdf0 fs/ext4/namei.c:2802
>  vfs_mkdir+0x419/0x690 fs/namei.c:3632
>  do_mkdirat+0x21e/0x280 fs/namei.c:3655
>  do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:359
>  entry_SYSCALL_64_after_hwframe+0x44/0xa9
> RIP: 0033:0x7f9ffaa79687
> Code: Bad RIP value.
> RSP: 002b:00007ffeb3197c38 EFLAGS: 00000246 ORIG_RAX: 0000000000000053
> RAX: ffffffffffffffda RBX: 000055c2e6155985 RCX: 00007f9ffaa79687
> RDX: 00007ffeb3197b00 RSI: 00000000000001ed RDI: 000055c2e6155985
> RBP: 00007f9ffaa79680 R08: 0000000000000100 R09: 0000000000000000
> R10: 000055c2e6155980 R11: 0000000000000246 R12: 00000000000001ed
> R13: 00007ffeb3197dc0 R14: 0000000000000000 R15: 0000000000000000
> 
> 
> ---
> This bug 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 syzkaller@googlegroups.com.
> 
> syzbot will keep track of this bug report. See:
> https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
> 