From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 289A2606A332 for ; Wed, 4 Nov 2026 02:49:26 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=jb96h4h0 Received: by kanga.kvack.org (Postfix) id EB78C6B05B2; Tue, 3 Nov 2026 21:49:24 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id E60386B05B3; Tue, 3 Nov 2026 21:49:24 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id D4F076B05B4; Tue, 3 Nov 2026 21:49:24 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) by kanga.kvack.org (Postfix) with ESMTP id A220E6B05B2 for ; Tue, 3 Nov 2026 21:49:24 -0500 (EST) Received: from smtpin21.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay02.hostedemail.com (Postfix) with ESMTP id 19ADA1203CE for ; Wed, 4 Nov 2026 02:49:24 +0000 (UTC) X-FDA: 85395905448.21.E8592E3 Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf03.hostedemail.com (Postfix) with ESMTP id 5D59720006 for ; Wed, 4 Nov 2026 02:49:22 +0000 (UTC) Authentication-Results: imf03.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=jb96h4h0; spf=pass (imf03.hostedemail.com: domain of sashiko-bot@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=sashiko-bot@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1793760562; b=OCgWMel3xlvEPUEUvBtTgggSreVC/cA9suDr09OHkI9gbvcDJ62VtK4irgRM6Mm1OCHVOr tps5OYpFLIDXVw4kT3N0gHuEge47SZELDYm4StItV2hIMBDQzhSm9s7xnb5yHYC6opdva+ FxXCpQa3eblstOgKNXseCnB37YrjeRQ= ARC-Authentication-Results: i=1; imf03.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=jb96h4h0; spf=pass (imf03.hostedemail.com: domain of sashiko-bot@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=sashiko-bot@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=1793760562; h=from:from:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=cGl7bC3fWAoAUhJbWEmSTM5Y06Elv8KWXkaBb9P48hA=; b=PDvIVBiDQBlXjBUYLCtrzSPbyeOhsxzRvcifBG+KQOif7sz1RH6I8vYeu4lXj/iA2323qn B0uuGPSFpjL9p+rTitinSwnlPEfj6KuBRXXwCN1u6VnI3bfL9RqLkUGjgdM14DP13i/W1a ZHBvJwvTzrrjlkeW5cJTijBtQfjfD/U= Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id 5DDAF43B2D; Wed, 4 Nov 2026 02:49:21 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 657D51F00919; Wed, 4 Nov 2026 02:49:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793760561; bh=cGl7bC3fWAoAUhJbWEmSTM5Y06Elv8KWXkaBb9P48hA=; h=From:Subject:Reply-To:To:Cc:In-Reply-To:References:Date; b=jb96h4h0oM3x4HuMId9uj2LqKZoeAZgCuatFL0X+g/wCJ7W3yMOe0X+dGWF5LZ1Bh RJgMrUz3AHHIUC+Z4+HAGKWnlgwAZ9sGm1hChg1XwsbZwTUL/TrZPNINyYw/XIX/ZG G30TzK2SZ8L+TUdKRouOFuOavuK9HgEczJgXAsaU0LjsPd6BEZYiIs9ndCujj6YC3M 74rzfop9P769vcC6l+1fnC6yfgQwNV3B8wKFg0bvJLdTiJ6mZxinQL54u8rpdtn6et ThQeKLK7GDRuz9JleE7CZdoIlyEP2yoD0Isb0vVwMAbdqEsQGFhpadeotBCvbBSezs SepM0zq9kLE7w== Message-ID: From: sashiko-bot@kernel.org Subject: Re: [RFC PATCH v2 2/5] mm/show_mem: Avoid blocking on zone->lock during Oops or panic Reply-To: sashiko-reviews@lists.linux.dev To: "Aaron Tomlin" , pmladek@suse.com, john.ogness@linutronix.de, rostedt@goodmis.org, senozhatsky@chromium.org, mingo@redhat.com, peterz@infradead.org, juri.lelli@redhat.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, bsegall@google.com, mgorman@suse.de, vschneid@redhat.com, kprateek.nayak@amd.com, akpm@linux-foundation.org, baoquan.he@linux.dev, rppt@kernel.org, pasha.tatashin@soleen.com, pratyush@kernel.org, ruirui.yang@linux.dev, david@kernel.org, ljs@kernel.org, liam@infradead.org, vbabka@kernel.org, surenb@google.com, mhocko@suse.com, kees@kernel.org, anna-maria@linutronix.de, frederic@kernel.org, tglx@kernel.org, mhiramat@kernel.org, mathieu.desnoyers@efficios.com, brendan.jackman@linux.dev, hannes@cmpxchg.org, ziy@nvidia.com, bigeasy@linutronix.de, clrkwllms@kernel.org Cc: kexec@lists.infradead.org, linux-mm@kvack.org, linux-trace-kernel@vger.kernel.org, linux-rt-devel@lists.linux.dev, linux-kernel@vger.kernel.org In-Reply-To: <20261103024453.922373-3-atomlin@atomlin.com> References: <20261103024453.922373-1-atomlin@atomlin.com> <20261103024453.922373-3-atomlin@atomlin.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Date: Wed, 04 Nov 2026 02:49:19 +0000 X-Stat-Signature: 689yxa3xqe317hfu1gyoa1bpm41945jc X-Rspam-User: X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 5D59720006 X-Spam-Status: No, score=-10.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_PASS,SPF_PASS autolearn=unavailable autolearn_force=no version=4.0.1 X-HE-Tag: 1793760562-964284 X-HE-Meta: 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 VbCUVPLr 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 X-Archived-By: Thank you for your contribution! Sashiko AI review found 1 potential issue(= s) to consider: - [Medium] mm/show_mem: false lock contention warning in show_free_areas() -- commit e1c6e11316c0b99b2f700b8251c5ed2b76aad84a Author: Aaron Tomlin mm/show_mem: Avoid blocking on zone->lock during Oops or panic This commit updates show_free_areas() in mm/show_mem.c to avoid uncondition= ally calling spin_lock_irqsave() on zone->lock during Oops, panic, or NMI/a= tomic contexts, skipping zones when acquiring the lock is unsafe or contend= ed. > diff --git a/mm/show_mem.c b/mm/show_mem.c > index b938cbcd774a1..77098077523a9 100644 > --- a/mm/show_mem.c > +++ b/mm/show_mem.c > @@ -367,10 +367,17 @@ static void show_free_areas(unsigned int filter, co= nst nodemask_t *nodemask, > continue; > if (show_mem_node_skip(filter, zone_to_nid(zone), nodemask)) > continue; > - show_node(zone); > - printk(KERN_CONT "%s: ", zone->name); > =20 > - spin_lock_irqsave(&zone->lock, flags); > + if (!can_spin_trylock() || in_nmi() || > + oops_in_progress || panic_in_progress()) { > + if (!can_spin_trylock() || > + !spin_trylock_irqsave(&zone->lock, flags)) { > + pr_warn("zone %s lock contended\n", zone->name); > + continue; > + } > + } else { > + spin_lock_irqsave(&zone->lock, flags); > + } [Severity: Medium] In show_free_areas(), when can_spin_trylock() returns false (such as in NMI= or hardirq context under CONFIG_PREEMPT_RT, or in NMI context under !CONFIG_SM= P): mm/internal.h:can_spin_trylock() { if (IS_ENABLED(CONFIG_PREEMPT_RT) && (in_nmi() || in_hardirq())) return false; /* On UP, spin_trylock() always succeeds even when it is locked */ if (!IS_ENABLED(CONFIG_SMP) && in_nmi()) return false; return true; } the inner !can_spin_trylock() check short-circuits before spin_trylock_irqsave() is ever called, yet still prints "zone %s lock contended" for every populated zone even when zone->lock is completely uncontended. The commit message also states: Check can_spin_trylock() and use spin_trylock_irqsave() when !can_spin_trylock(), in_nmi(), oops_in_progress, or panic_in_progress() is active Additionally, because show_node(zone) is moved after spin_unlock_irqrestore= () below, skipping a zone here only logs zone->name (for example, Normal or DMA32) without the NUMA node ID on CONFIG_NUMA systems. Should the !can_spin_trylock() case avoid claiming that zone->lock is contended (and match the commit message description), and should the skipped zone message include the node ID? --=20 Sashiko AI review =C2=B7 https://sashiko.dev/#/patchset/20261103024453.9223= 73-1-atomlin@atomlin.com?part=3D2