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 7B658C4332F for ; Mon, 21 Nov 2022 09:41:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230261AbiKUJlS (ORCPT ); Mon, 21 Nov 2022 04:41:18 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49830 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230260AbiKUJlR (ORCPT ); Mon, 21 Nov 2022 04:41:17 -0500 Received: from smtp-out1.suse.de (smtp-out1.suse.de [195.135.220.28]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D5F4F51C08; Mon, 21 Nov 2022 01:41:16 -0800 (PST) Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out1.suse.de (Postfix) with ESMTPS id 89EBD21AC3; Mon, 21 Nov 2022 09:41:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_rsa; t=1669023675; h=from:from:reply-to: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=x4svcpQifmjNQouc72E4WUVyl0JmTYJ7FIcleg5VVfk=; b=Za0f7AJe52OAjDc+cUdFIv/Y3rnSPBO8l20gpsDrU1H93th+sbNje4hWKKXjRqFXYV3YrY RqVP7Mcm/stCzCkCyaKDEXv1yAc9FnowwdBJbI8KnQ9J4peC3pcY/zvjV41XJ1jrL4svS/ gyMG0jMUz7BfWw+tSp9ZGPMdecMJuTg= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_ed25519; t=1669023675; h=from:from:reply-to: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=x4svcpQifmjNQouc72E4WUVyl0JmTYJ7FIcleg5VVfk=; b=NFMaWY01+uSO0f1Y0Zr7QgM+Cnj/KWqdg9BIFqEYLqsVklQOuUf4c23ApJ7B9VcYgP5ynm +M8hE/zF9aNf0vCQ== Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id 26C491377F; Mon, 21 Nov 2022 09:41:15 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id fMYECLtHe2MkdAAAMHmgww (envelope-from ); Mon, 21 Nov 2022 09:41:15 +0000 Date: Mon, 21 Nov 2022 10:41:13 +0100 From: Petr Vorel To: Sergey Senozhatsky Cc: Martin Doucha , Minchan Kim , ltp@lists.linux.it, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, Nitin Gupta , Jens Axboe , OGAWA Hirofumi , Yang Xu Subject: Re: [PATCH 0/1] Possible bug in zram on ppc64le on vfat Message-ID: Reply-To: Petr Vorel References: <20221107191136.18048-1-pvorel@suse.cz> <3ac740c0-954b-5e68-b413-0adc7bc5a2b5@suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org Hi Sergey, > On (22/11/10 15:29), Martin Doucha wrote: > > New version of LTP test zram01 found a sysfile issue with zram devices > > mounted using VFAT filesystem. When when all available space is filled, e.g. > > by `dd if=/dev/zero of=/mnt/zram0/file`, the corresponding sysfile > > /sys/block/zram0/mm_stat will report that the compressed data size on the > > device is 0 and total memory usage is also 0. LTP test zram01 uses these > > values to calculate compression ratio, which results in division by zero. > > The issue is specific to PPC64LE architecture and the VFAT filesystem. No > > other tested filesystem has this issue and I could not reproduce it on other > > archs (s390 not tested). The issue appears randomly about every 3 test runs > > on SLE-15SP2 and 15SP3 (kernel 5.3). It appears less frequently on SLE-12SP5 > > (kernel 4.12). Other SLE version were not tested with the new test version > > yet. The previous version of the test did not check the VFAT filesystem on > > zram devices. > Whoooaa... > > I've tried to debug the issue and collected some interesting data (all > > values come from zram device with 25M size limit and zstd compression > > algorithm): > > - mm_stat values are correct after mkfs.vfat: > > 65536 220 65536 26214400 65536 0 0 0 > > - mm_stat values stay correct after mount: > > 65536 220 65536 26214400 65536 0 0 0 > > - the bug is triggered by filling the filesystem to capacity (using dd): > > 4194304 0 0 26214400 327680 64 0 0 > Can you try using /dev/urandom for dd, not /dev/zero? > Do you still see zeroes in sysfs output or some random values? I'm not sure if Martin had time to rerun the test. I was not able to reproduce the problem any more on machine where the test was failing. But I'll have look into this during this week. Kind regards, Petr