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([2601:188:c100:5710:627d:9ff:fe85:9ade]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-6e65d779201sm21536016d6.2.2025.02.14.06.17.36 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 14 Feb 2025 06:17:39 -0800 (PST) From: Waiman Long X-Google-Original-From: Waiman Long Message-ID: <812ea88a-b79e-49e0-ab3b-83cd40b2851e@redhat.com> Date: Fri, 14 Feb 2025 09:17:35 -0500 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [syzbot] [cgroups?] possible deadlock in __run_timer_base (2) To: Peter Zijlstra , Waiman Long Cc: syzbot , cgroups@vger.kernel.org, hannes@cmpxchg.org, linux-kernel@vger.kernel.org, mkoutny@suse.com, syzkaller-bugs@googlegroups.com, tj@kernel.org References: <67a9136a.050a0220.110943.001e.GAE@google.com> <2aaa1663-fa9c-43ce-9421-60019899bac1@redhat.com> <20250214101959.GH21726@noisy.programming.kicks-ass.net> Content-Language: en-US In-Reply-To: <20250214101959.GH21726@noisy.programming.kicks-ass.net> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 2/14/25 5:19 AM, Peter Zijlstra wrote: > On Tue, Feb 11, 2025 at 09:14:12PM -0500, Waiman Long wrote: >> On 2/9/25 3:43 PM, syzbot wrote: >>> Hello, >>> >>> syzbot found the following issue on: >>> >>> HEAD commit: 92514ef226f5 Merge tag 'for-6.14-rc1-tag' of git://git.ker.. >>> git tree: upstream >>> console output: https://syzkaller.appspot.com/x/log.txt?x=179453df980000 >>> kernel config: https://syzkaller.appspot.com/x/.config?x=1909f2f0d8e641ce >>> dashboard link: https://syzkaller.appspot.com/bug?extid=ed801a886dfdbfe7136d >>> compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40 >>> >>> Unfortunately, I don't have any reproducer for this issue yet. >>> >>> Downloadable assets: >>> disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/7feb34a89c2a/non_bootable_disk-92514ef2.raw.xz >>> vmlinux: https://storage.googleapis.com/syzbot-assets/c4d8b91f8769/vmlinux-92514ef2.xz >>> kernel image: https://storage.googleapis.com/syzbot-assets/c24ec4365966/bzImage-92514ef2.xz >>> >>> IMPORTANT: if you fix the issue, please add the following tag to the commit: >>> Reported-by: syzbot+ed801a886dfdbfe7136d@syzkaller.appspotmail.com >> This problem should be fixed by the following upstream patch once it is >> merged into mainline. >> >> https://lore.kernel.org/lkml/20250127013127.3913153-1-longman@redhat.com/ >> > AFAICT all these lockdep reports are because of an earlier warning. Fix > warning, report goes away. Notably: > >>> _printk+0xd5/0x120 kernel/printk/printk.c:2457 >>> __report_bug lib/bug.c:195 [inline] >>> report_bug+0x346/0x500 lib/bug.c:219 >>> handle_bug+0x60/0x90 arch/x86/kernel/traps.c:285 >>> exc_invalid_op+0x1a/0x50 arch/x86/kernel/traps.c:309 >>> asm_exc_invalid_op+0x1a/0x20 arch/x86/include/asm/idtentry.h:621 >>> expire_timers kernel/time/timer.c:1827 [inline] > IOW I think we're focusing on the wrong thing here. > >> Peter, are you planning to merge this patch? This is another instance where >> the old way of calling wake_up_process() inside the lock critical region can >> lead to deadlock. > I still don't love the Changelog, but yeah, I suppose I can pick it up. > But I see Boqun took it and I'll get it eventually. > > No real hurry there I suppose. I know my changelog is sometimes too verbose and may contain non-important information. I will try to improve that in the future. Cheers, Longman >