From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from desiato.infradead.org (desiato.infradead.org [90.155.92.199]) (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 C1530221FD4; Thu, 24 Apr 2025 10:40:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=90.155.92.199 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745491244; cv=none; b=rQmoxGiQ3q/hOWF4bxApjMlafBUI0xzzbB4QhXTlX4IrDSg3Ygwb5XlcfxXnJ6lkBduOfqST0yIUnKOHTu+0afa1PP4yoiq6DnSCcc797dOy4P3DkNv+AHeUQxnM7ZiPGO+6ycR20E6+6zKVRxCLFOINxPBY6OFuYWbQH4/8T+4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745491244; c=relaxed/simple; bh=VfgAF5tdFF9XvVPd4mOHkk9ukH3mDa8hX3KuZyWTvrQ=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=CfjwTofH/LCDXpHDz2nWcfFontXv9tI1/cmgXXcuNZ7HH7Jd8Ud57oRglI/OdmHOFfL/lumYtpMMtV+prZEMqzFi6zjNJ854QiB6d17XnZlXMIuecC9uowv09pFcc5Q0QmBAt2v5LghCsQ5tVPQzv9UfyN0Y1aUPycdy13MLFLk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=b5ckuwSX; arc=none smtp.client-ip=90.155.92.199 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="b5ckuwSX" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=VfgAF5tdFF9XvVPd4mOHkk9ukH3mDa8hX3KuZyWTvrQ=; b=b5ckuwSXgvEOn919rq9fQqALbl dM+/bmsvO9CxaXpneQ/2p+OFVo9x/wtgn32Gt0ICw4SKpaLqh7gSD1W5e5WST7NL3QDlnktrVj6uY f/amEGkIFYSp+KUpXoC5esbwmft3fohEEvDFZrhyBsLjULoklw4KLzjn9bXyGPFmK7AjtYlQlBuaM SW9Va9uxdrf2l/FNfmlH/frKmqZhAZCpaInPgvtC/O+FwPxAO3GGq7RIHDGx+CHBIkiW6Ge62RCdl dvzS9JSla0yBDKG7hV4OMa9WyR/mGCp2lVew1XbZkyC4T2cwL1/h3Or10OZcw0xQCEJKupn/LKfgZ xw3+ow3w==; Received: from 77-249-17-252.cable.dynamic.v4.ziggo.nl ([77.249.17.252] helo=noisy.programming.kicks-ass.net) by desiato.infradead.org with esmtpsa (Exim 4.98.1 #2 (Red Hat Linux)) id 1u7u0K-0000000BkTg-1D0W; Thu, 24 Apr 2025 10:40:28 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id C4B283002CE; Thu, 24 Apr 2025 12:40:27 +0200 (CEST) Date: Thu, 24 Apr 2025 12:40:27 +0200 From: Peter Zijlstra To: Baisheng Gao Cc: Ingo Molnar , Arnaldo Carvalho de Melo , Namhyung Kim , Mark Rutland , Alexander Shishkin , Jiri Olsa , Ian Rogers , Adrian Hunter , "reviewer:PERFORMANCE EVENTS SUBSYSTEM" , "open list:PERFORMANCE EVENTS SUBSYSTEM" , "open list:PERFORMANCE EVENTS SUBSYSTEM" , cixi.geng@linux.dev, hao_hao.wang@unisoc.com Subject: Re: [PATCH] perf/core: Handling the race between exit_mmap and perf sample Message-ID: <20250424104027.GG19534@noisy.programming.kicks-ass.net> References: <20250424025429.10942-1-baisheng.gao@unisoc.com> Precedence: bulk X-Mailing-List: linux-perf-users@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250424025429.10942-1-baisheng.gao@unisoc.com> On Thu, Apr 24, 2025 at 10:54:29AM +0800, Baisheng Gao wrote: > In order to fix the race condition between exit_mmap and > perf_output_sample below, forbidding to copy the user stack > of an exiting process. You cannot say "the race" and not describe the race. A stack dump is not a description of a race.