From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id E46DDC83F25 for ; Wed, 23 Jul 2025 07:31:32 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 58F936B0095; Wed, 23 Jul 2025 03:31:32 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 519D96B0096; Wed, 23 Jul 2025 03:31:32 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 3E22D6B0098; Wed, 23 Jul 2025 03:31:32 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0014.hostedemail.com [216.40.44.14]) by kanga.kvack.org (Postfix) with ESMTP id 29ED46B0095 for ; Wed, 23 Jul 2025 03:31:32 -0400 (EDT) Received: from smtpin21.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay09.hostedemail.com (Postfix) with ESMTP id BC5BD80611 for ; Wed, 23 Jul 2025 07:31:31 +0000 (UTC) X-FDA: 83694709182.21.93B5A79 Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by imf05.hostedemail.com (Postfix) with ESMTP id 13C2D10000A for ; Wed, 23 Jul 2025 07:31:29 +0000 (UTC) Authentication-Results: imf05.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=qylPVJnd; spf=pass (imf05.hostedemail.com: domain of kees@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=kees@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1753255890; h=from:from:sender: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: in-reply-to:in-reply-to:references:references:dkim-signature; bh=l0pwS/0qwO3mUHXOuArQekwiv6Gr4ejvt921/Tg54XA=; b=nkYwZ6fl27iEhdwq2pklxU29qWUxhu7BY8YvxQyfvA/E+261aV8Zcy9MiI1ldOIxwlhxbJ zYqvR/hHz9JMCazdo8oLHOicKJ3k7/2ogMAY8mzr5KiI5OMcGn/n1YlxhzsgqFfDEqqotA zpBvBwHjUuOhU/NFPHbYMGjr1KoErFw= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1753255890; a=rsa-sha256; cv=none; b=oiYcjf1Uw8Nz9ldqsvcd8T4QjbyzqZlTLt8v7MRhsNd6w9iz4JCMp05ConkkMKGva9W4jL FwsXLfAybHMlEzFJNWxdINTJv08xGCsmmrKXZOAs4BZ/khE6olXz03Bi8pqCvRC0lrXUrU Ja4ilyTVBwdzlxTlww79JlNgDz5PZm0= ARC-Authentication-Results: i=1; imf05.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=qylPVJnd; spf=pass (imf05.hostedemail.com: domain of kees@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=kees@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by tor.source.kernel.org (Postfix) with ESMTP id 5446E6691E; Wed, 23 Jul 2025 07:31:29 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id E67BBC4CEE7; Wed, 23 Jul 2025 07:31:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1753255889; bh=MPGvewvNycI1DIvPEIiTbeqHEpcxVhIqLFJUB/m7jWc=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=qylPVJndUKKL8DwoPy3gYpl9fmvTooHAbAQ1daxBPDeDKDCk8SWUMFU1Ti/jVnKyl mAc74zgzYpJ3AwTa63E7zdNXA6xzOXajAlcIXeaxxm3FkvCWW1Kmff5APHgxYHA+68 kN5yu//7bzB9iZ8GeUCBFaUoGt/gCR23jQa7ofrrOQUuc4UYCBl1Xszn9B3bbEskcT 1H3Q24WJFyTgc6R8GumQq8Pe726lZgf0noazkhGqNA5NfoWBAqNZeSIibXN8vjXnvn 6aZCpI3OSBpx5loAUugrwM/2SoyPhkTjbhB/dtPmousTLLeCm8Mu1pJP9q9fakK4H4 ICSGWIrApgkIw== Date: Wed, 23 Jul 2025 00:31:28 -0700 From: Kees Cook To: Xuanye Liu Cc: Ingo Molnar , Peter Zijlstra , Juri Lelli , Vincent Guittot , Andrew Morton , David Hildenbrand , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Valentin Schneider , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm: add stack trace when bad rss-counter state is detected Message-ID: <202507230031.52B5C2B53@keescook> References: <20250723072350.1742071-1-liuqiye2025@163.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250723072350.1742071-1-liuqiye2025@163.com> X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 13C2D10000A X-Stat-Signature: ynh55ixjgp1pprgf61tffs7phbhmj1a1 X-Rspam-User: X-HE-Tag: 1753255889-626461 X-HE-Meta: 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 JXJ7cOj5 UdJ75xyN3FVRU7NbayJEq3EtAJS4zl66HcMg4qrxKAIB0OL7mxDUL7EwMRVmqgkQloTCdhIy1ILdWsa/nB+avBcsA9YIHPVFWBXMCPO7AuPqhOtnPchS4Yiyx6aJqsbMwbxQlyyfCBOQThQSnXZ9U7hkOQ9PjlXHa2Qo8+I4JA/qE3+GkWRMVLPwhz8jMzo4Xb9qkxv7rnQx1hvG1kL1FgBYjxMnD82Rt08K/cERvMxaozCgrurJtvPLoJCE7C7HlF+YY5I+6GmVXcY+ameUAknDjXIiIxGS44SnrwbKJkF0y/h+ZT8oq67qyjTkhe4e61dtzBQ2kVSwM6GzImapLIXu39wuH8cW/EkNLhlTcdBYoa8s= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed, Jul 23, 2025 at 03:23:49PM +0800, Xuanye Liu wrote: > The check_mm() function verifies the correctness of rss counters in > struct mm_struct. Currently, it only prints an alert when a bad > rss-counter state is detected, but lacks sufficient context for > debugging. > > This patch adds a dump_stack() call to provide a stack trace when > the rss-counter state is invalid. This helps developers identify > where the corrupted mm_struct is being checked and trace the > underlying cause of the inconsistency. Why not just convert the pr_alert to a WARN? -Kees > > Signed-off-by: Xuanye Liu > --- > kernel/fork.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > diff --git a/kernel/fork.c b/kernel/fork.c > index cfe2f1df5f27..d38f1c5270ea 100644 > --- a/kernel/fork.c > +++ b/kernel/fork.c > @@ -584,9 +584,11 @@ static void check_mm(struct mm_struct *mm) > for (i = 0; i < NR_MM_COUNTERS; i++) { > long x = percpu_counter_sum(&mm->rss_stat[i]); > > - if (unlikely(x)) > + if (unlikely(x)) { > pr_alert("BUG: Bad rss-counter state mm:%p type:%s val:%ld\n", > mm, resident_page_types[i], x); > + dump_stack(); > + } > } > > if (mm_pgtables_bytes(mm)) > -- > 2.43.0 > -- Kees Cook