From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) (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 A79AB2641FB for ; Wed, 5 Nov 2025 12:40:10 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=90.155.50.34 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762346413; cv=none; b=M5OtABHmJgaQwB+cJdx2SrTzsfsgmwyeTnzeMAnL0WZCR6j19lErWP9Nz32gs/73IEAefvXG4xgkUbs+qXPXq7Mb+WUnxm51gJdFEwS9JY+nfav8E8c2IoIpYco9GbaNqvf6JbFyzqCWJWP8H8GJIo+GPXISD85MIVQHyEuHwNc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762346413; c=relaxed/simple; bh=9vKj67iakbcTIdLLoTrk3T6B82VmWN8TfwxCHjEY9NI=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=oVXPzkLXAair+G+N0I8dQq+Qp8TaZZDNczNKgi68/uZX5VYLHmW/J8y/brzuD+e1/9J4/MSdxfO/rzydglI7j54hLiy1v5HGPp06Wd2z1k+SX393oWuGwnokblUDylCK/uAfB9z5LuEqc5uVv5S7um2K3jSFs7bdyuPM7YHRogQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (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=XUj/OKLV; arc=none smtp.client-ip=90.155.50.34 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (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="XUj/OKLV" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; 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=9vKj67iakbcTIdLLoTrk3T6B82VmWN8TfwxCHjEY9NI=; b=XUj/OKLVHsd2xg3I7IDn7ozpcT 98ghxrY/sODS459O4KfecoX+BiCTQKsLqudfCEsPiFO3fD69pSc1+5UsvaziVEDOeYWewfZyUzv81 KUILwNJjp58pnx7DpupEHJDfBbJ0XMr8FlFDnnRv8yoDTPOvAXexrOKsrQRsY9ijBwVkGYTyW9Nzm xRFWu0AevRvuXcD6ZiG15VtwBIf+CHGXx/OV3ZSIYux3WwxRBjnCZkEyMYaThoD9fGfRklAkOLI16 j9ONwP/pDN5gRcjyLdRJiAJ+PY4qItsqKQSRJtVxsRBndLfOKs6QDURGXXKjoJ+1Ven+wgvafg++Z pkSjpL6w==; Received: from 77-249-17-252.cable.dynamic.v4.ziggo.nl ([77.249.17.252] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.98.2 #2 (Red Hat Linux)) id 1vGcnp-00000005zMG-3wcz; Wed, 05 Nov 2025 12:39:55 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id A66EF300230; Wed, 05 Nov 2025 13:39:54 +0100 (CET) Date: Wed, 5 Nov 2025 13:39:54 +0100 From: Peter Zijlstra To: Zicheng Qu Cc: mingo@redhat.com, juri.lelli@redhat.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, vschneid@redhat.com, linux-kernel@vger.kernel.org, wulibin163@126.com, tanghui20@huawei.com, zhangqiao22@huawei.com, judy.chenhui@huawei.com Subject: Re: [PATCH EEVDF NULL deref] sched/eevdf: Fix NULL deref when avg_vruntime nears overflow Message-ID: <20251105123954.GM3245006@noisy.programming.kicks-ass.net> References: <20251103130441.1013188-1-quzicheng@huawei.com> <20251103202611.GE3245006@noisy.programming.kicks-ass.net> <7cdcc98e-990e-4408-ba75-57dd0229316e@huawei.com> Precedence: bulk X-Mailing-List: linux-kernel@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: <7cdcc98e-990e-4408-ba75-57dd0229316e@huawei.com> On Wed, Nov 05, 2025 at 06:47:40PM +0800, Zicheng Qu wrote: > This is the reproduction patch. We encountered a similar issue on a > normally running kernel, and after analysis, we deliberately constructed > a comparable scenario. Since it is difficult to control the conditions > from user space, we proactively modified certain parts of the kernel > code to simulate the issue (the code includes detailed explanations). Thanks! > As for the zero_vruntime patch, after applying it, we have not > observed any crashes over than 24 hours. Excellent, I'll go think about the SCHED_CORE case and make it a proper patch then.