From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-182.mta0.migadu.com (out-182.mta0.migadu.com [91.218.175.182]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C4A4F351C20 for ; Thu, 16 Jul 2026 06:56:25 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.182 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784184987; cv=none; b=cYY/f8tWDqptlPkbmYKmJE6x3gFy4hWrvGFxf3a73BZtWpdaR9xkz+SskW/GuLEVA7Fy3VArvns+IRz19iUWFBwtmtIhIBMp+kroi4FQg1yyWjD4TkgiPps66Z+ykCK1sxFZusxI3XEQ+59K3QuhG3R/+NChHcjB+KcKdxna9eY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784184987; c=relaxed/simple; bh=Cv/N1L+YNfNNoDZ8ZKoV/S1AELPfUlzjJA1DbA9Gbz4=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=bEJEyp9DMz3QvOKk2MJGH1/FeK44YA73A6BA8D34S6ZxjVoUEPmVy6juoS0evlpxxDR5Bmc5R9wF3KWLaJhZeSaIqteLmbpK3mOrGcHOHaxiSP36x7DlapphCvSVKu0SRzYMmGhwezCFdQteY4h97GJBdYTxD81XmhRIRbwSRHI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=FwIknOuL; arc=none smtp.client-ip=91.218.175.182 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="FwIknOuL" Message-ID: <2528a896-a0f4-46ef-a7c5-83c7c8a2980a@linux.dev> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1784184983; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=xYiGjNxhXvM9lkBqPYl3fjOblmr5js/K8FgoFt45DIA=; b=FwIknOuLo4Fc77ndz5SZrExsHV8VRIXWTffAruI+Aprr35oOG6fxNkRgOBeU11CsJf4kYf CgNa+dBygy1NfJs1Dop6/KGWg/w0+zz4U3H+1bKkr2Y2LlxskZP7OVmTBvkBomlWwn1AwA QfbI3dx4v8II2UtPg8wFmwdiDFKOTaA= Date: Thu, 16 Jul 2026 14:56:13 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Subject: Re: [PATCH bpf-next] bpf:syscall: Log error code on trampoline unlink failure To: xu.xin16@zte.com.cn Cc: ast@kernel.org, daniel@iogearbox.net, john.fastabend@gmail.com, andrii@kernel.org, eddyz87@gmail.com, memxor@gmail.com, martin.lau@linux.dev, song@kernel.org, yonghong.song@linux.dev, jolsa@kernel.org, emil@etsalapatis.com, bpf@vger.kernel.org, linux-kernel@vger.kernel.org, xu.xin@linux.dev References: <20260716142613346GZ_NR5Zi4awr3wEReuIMG@zte.com.cn> X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Leon Hwang Content-Language: en-US In-Reply-To: <20260716142613346GZ_NR5Zi4awr3wEReuIMG@zte.com.cn> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT On 16/7/26 14:26, xu.xin16@zte.com.cn wrote: >>> Well, the crash may happen when the kernel is booting, or too hard to reproduce, >>> in which case, bpftrace does not work. >> >> >> Do you enable kernel.panic_on_warn sysctl? >> >> If it's not enabled, the kernel won't crash, I think. > > I'd like to clarify that the panic in our case is not triggered by the WARN itself. > Instead, the real crash is a use‑after‑free (UAF) that happens when one CPU is > executing a trampoline while another CPU is concurrently freeing it. This results > in an illegal instruction (or page fault) at the PC, which is fatal and will panic > the kernel regardless of panic_on_warn – because it's an Oops with Fatal exception > in interrupt. Why not fix the root cause instead? If you want some help from upstream to fix the root cause, pls provide the crash dmesg and the reproducing demo. Thanks, Leon