From mboxrd@z Thu Jan 1 00:00:00 1970 From: Edward Shishkin Subject: Re: [xfstests/generic/081] Kernel panic with reg40 plugin and R4-for-4.1.5.patch Date: Thu, 10 Sep 2015 22:47:32 +0200 Message-ID: <55F1EC64.2060307@gmail.com> References: <55F1D7E9.2000209@gmail.com> <55F1E3C9.5080109@gmail.com> Mime-Version: 1.0 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=message-id:date:from:user-agent:mime-version:to:cc:subject :references:in-reply-to:content-type:content-transfer-encoding; bh=jIFJI2YiMzG/dByyYAJmi+zUeVUM77HsklGn3DfJx3o=; b=jVYDty0g0w2jF7PE7lSA190jiW1UxzL+XxdwLezm2ZCOcu8TaQZFUsmjBVXovtjs0n R66YxU1ba8g6c0LYiDrOlskdxcSKsD4Z5TBeeKf6Y/V53IU2Y4XK7YeneUU3dw3xjloH 7PZLFDcHx5eS6kfixHWJdMB/D6zJ3nx9YPVm/EkQOMZyx5qP9kbSR43PyUJa/6QGsLSU hyk35AVCE7ol/NyxLuD3JtSUlb1WgBFx894I+uq9MsFx302w9EWb8hQeBBU0pTnDtrSm 8zqXlOW2Z6UCqpN76mPujVmoeztB6ecDYTQGJg3ieDx3DcUwoxuYSUPS3b1Lt8Y16BtU 5VNg== In-Reply-To: Sender: reiserfs-devel-owner@vger.kernel.org List-ID: Content-Type: text/plain; charset="utf-8"; format="flowed" To: =?UTF-8?B?RHXFoWFuIMSMb2xpxIc=?= Cc: reiserfs-devel On 09/10/2015 10:21 PM, Du=C5=A1an =C4=8Coli=C4=87 wrote: > Does dm snapshot returns EIO when filled? > From Documentation/device-mapper/snapshot.txt : > > " will often be > smaller than the origin and if it fills up the snapshot will become > useless and be disabled, returning errors. So it is important to mon= itor > the amount of free space and expand the before it fills = up." OK, I agree :) > > On Thu, Sep 10, 2015 at 10:10 PM, Edward Shishkin > wrote: >> >> On 09/10/2015 09:42 PM, Du=C5=A1an =C4=8Coli=C4=87 wrote: >>> On Thu, Sep 10, 2015 at 9:20 PM, Edward Shishkin >>> wrote: >>>> Actually, this is not a regression. >>>> The attached patch prevents the panic. >>>> By default on IO errors reiser4 partition will be remounted as >>>> "readonly". >>>> >>>> No ideas why accessing /dev/dm-X causes IO error. >>>> Reiser4 is not the culprit ;) You can narrow down this, if interes= ting. >>>> I think that something is wrong with LVM settings... >>>> >>> I looked more into this: This test fills up dm snapshot (writes 5MB= to >>> 4MB snapshot) so we get IO error because it's full. >> >> >> IO error because of no space - it is very strange, >> especially when reading the device (as in my case): >> >> # dd if=3D/dev/dm-3 of=3D/dev/null bs=3D4096 count=3D1 >> >> >> >>> It doesn't trigger >>> on ccreg40 because ccreg40 compresses data so 5MB of compressible d= ata >>> < 4MB space ;) >>> xfstests uses compressible data for disk full tests so on ccreg40 t= hey >>> give false positive. Are ccreg40 and reg40 code paths for disk full >>> situation the same? >>> I'll look into fixing xfstetsts. >>>> Thanks, >>>> Edward. >>>> >>>> >>>> >>>> On 09/04/2015 09:35 AM, Du=C5=A1an =C4=8Coli=C4=87 wrote: >>>>> Kernel: 4.1.6 >>>>> R4 patch: 4.1.5 >>>>> Test: xfstests/generic/081 "Test I/O error path by fully filling = an dm >>>>> snapshot." >>>>> >>>>> Test passes cleanly with ccreg40 but kernel panics with reg40 plu= gin. >>>>> Picture of the panic, as I had no other means of capturing it, is= in >>>>> attachment. >>>>> >>>>> xfstests local.config section: >>>>> >>>>> [r4Hybrid] >>>>> MKFS_OPTIONS=3D"-o create=3Dreg40" >>>>> MOUNT_OPTIONS=3D"-o noatime" >>>>> >>>>> Have a nice day. >>>>> >>>>> Dushan >>>> -- To unsubscribe from this list: send the line "unsubscribe reiserfs-deve= l" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html