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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id B05E3C433F5 for ; Wed, 6 Apr 2022 01:10:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1840235AbiDFBHm (ORCPT ); Tue, 5 Apr 2022 21:07:42 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60308 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1446546AbiDEPos (ORCPT ); Tue, 5 Apr 2022 11:44:48 -0400 Received: from smtp-out1.suse.de (smtp-out1.suse.de [195.135.220.28]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4A553220F0 for ; Tue, 5 Apr 2022 07:17:49 -0700 (PDT) Received: from relay2.suse.de (relay2.suse.de [149.44.160.134]) by smtp-out1.suse.de (Postfix) with ESMTP id 8D5FF210FD; Tue, 5 Apr 2022 14:17:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1649168267; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=BvTEfQ7kJIqh1i2okodWWZaOv98eaMhKZYSbbqfbqYA=; b=d9XBmlgmY3A70bvfCltmJ743BPcZgNoVojfxXvCHM8d7PWevIOpBrYxcAk0yedES0cZCmP CNOw62MQnC5Y4eifXYgoEwgM3YY+C/9/0UUoSLlmAslbdcz2H+losrp4380tiGFQD+6SFh 7K1OE/Qh8ajN+ALwVhvhTrWzzaaXa5M= Received: from suse.cz (unknown [10.100.201.86]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by relay2.suse.de (Postfix) with ESMTPS id D2921A3B8A; Tue, 5 Apr 2022 14:17:46 +0000 (UTC) Date: Tue, 5 Apr 2022 16:17:43 +0200 From: Michal Hocko To: Alexander Sverdlin Cc: Nicholas Piggin , Alexander Duyck , Matthew Wilcox , Hugh Dickins , Yu Zhao , Mel Gorman , Lee Schermerhorn , Sasha Levin , Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: mm: swap: locking in release_pages() Message-ID: References: <89009285-c75d-0f09-5b08-d133c42a18f9@nokia.com> <404b3d6e-510e-c15f-a28b-7425bcc67cc2@nokia.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <404b3d6e-510e-c15f-a28b-7425bcc67cc2@nokia.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue 05-04-22 16:00:54, Alexander Sverdlin wrote: > Hello Michal! > > On 05/04/2022 13:45, Michal Hocko wrote: > >>>> 1. Crash of v5.4.170 on an ARM32 machine: > >>>> > >>>> Unable to handle kernel NULL pointer dereference at virtual address 00000104 > >>>> pgd = e138149d > >>>> [00000104] *pgd=84d2fd003, *pmd=8ffd6f003 > >>>> Internal error: Oops: a07 [#1] PREEMPT SMP ARM > >>>> ... > >>>> CPU: 1 PID: 6172 Comm: AaSysInfoRColle Tainted: G B O 5.4.170-... #1 > >>>> Hardware name: Keystone > >>>> PC is at release_pages+0x194/0x358 > >>>> LR is at release_pages+0x10c/0x358 > >>> Which LOC does this correspond to? (faddr2line should give you a nice > >>> output). > >> Sorry, I forgot this info in the initial report: > >> > >> this is indeed the del_page_from_lru_list() in this crash. > > Could you be more specific please? Is the problem in list_del or > > update_lru_size? > > static inline void __list_del(struct list_head * prev, struct list_head * next) > { > next->prev = prev; <-- OK, I see. AFAICS this means that entry->next is NULL which doesn't look like somebody else has done list_del as that would leave poison values behind. Maybe somebody has clobbered the page state. In any case I would recommend reproducing without stable patches and/or with the current Linus tree. -- Michal Hocko SUSE Labs