From: Will Deacon <will@kernel.org>
To: syzbot <syzbot+b29d18a34746f34c94cc@syzkaller.appspotmail.com>
Cc: catalin.marinas@arm.com, linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com,
maz@kernel.org
Subject: Re: [syzbot] [arm?] BUG: using __this_cpu_read() in preemptible code in __delay
Date: Thu, 26 Feb 2026 18:25:14 +0000 [thread overview]
Message-ID: <aaCQCnM9eaBK_ON0@willie-the-truck> (raw)
In-Reply-To: <69a06135.050a0220.305b49.0024.GAE@google.com>
On Thu, Feb 26, 2026 at 07:05:25AM -0800, syzbot wrote:
> syzbot found the following issue on:
>
> HEAD commit: 32a92f8c8932 Convert more 'alloc_obj' cases to default GFP..
> git tree: upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=1019fc02580000
> kernel config: https://syzkaller.appspot.com/x/.config?x=b77d736d2f4fe1b1
> dashboard link: https://syzkaller.appspot.com/bug?extid=b29d18a34746f34c94cc
> compiler: aarch64-linux-gnu-gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44
> userspace arch: arm64
>
> Unfortunately, I don't have any reproducer for this issue yet.
>
> Downloadable assets:
> disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/fa3fbcfdac58/non_bootable_disk-32a92f8c.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/aabf4d7d9d6a/vmlinux-32a92f8c.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/0367e274b699/Image-32a92f8c.gz.xz
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+b29d18a34746f34c94cc@syzkaller.appspotmail.com
>
> BUG: using __this_cpu_read() in preemptible [00000000] code: syz.0.1012/5537
> caller is __this_cpu_preempt_check+0x20/0x40 lib/smp_processor_id.c:64
> CPU: 0 UID: 0 PID: 5537 Comm: syz.0.1012 Tainted: G L syzkaller #0 PREEMPT
> Tainted: [L]=SOFTLOCKUP
> Hardware name: linux,dummy-virt (DT)
> Call trace:
> show_stack+0x18/0x24 arch/arm64/kernel/stacktrace.c:499 (C)
> __dump_stack lib/dump_stack.c:94 [inline]
> dump_stack_lvl+0x7c/0xb0 lib/dump_stack.c:120
> dump_stack+0x1c/0x28 lib/dump_stack.c:129
> check_preemption_disabled+0xe0/0xe8 lib/smp_processor_id.c:47
> __this_cpu_preempt_check+0x20/0x40 lib/smp_processor_id.c:64
> __arch_counter_get_cntvct_stable arch/arm64/include/asm/arch_timer.h:195 [inline]
> __delay+0x40/0x374 arch/arm64/lib/delay.c:39
> __const_udelay+0x48/0x64 arch/arm64/lib/delay.c:66
> udelay include/asm-generic/delay.h:62 [inline]
This should be fixed by the first patch in this series:
https://lore.kernel.org/r/20260226082234.26707-1-maz@kernel.org
I'll queue that today.
Will
#syz fix: arm64: Fix sampling the "stable" virtual counter in preemptible section
prev parent reply other threads:[~2026-02-26 18:25 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-02-26 15:05 [syzbot] [arm?] BUG: using __this_cpu_read() in preemptible code in __delay syzbot
2026-02-26 18:25 ` Will Deacon [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=aaCQCnM9eaBK_ON0@willie-the-truck \
--to=will@kernel.org \
--cc=catalin.marinas@arm.com \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=maz@kernel.org \
--cc=syzbot+b29d18a34746f34c94cc@syzkaller.appspotmail.com \
--cc=syzkaller-bugs@googlegroups.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox