From: Changheun Lee <nanich.lee@samsung.com>
To: alex_y_xu@yahoo.ca
Cc: axboe@kernel.dk, ming.lei@redhat.com, tytso@mit.edu,
bvanassche@acm.org, bgoncalv@redhat.com, dm-crypt@saout.de,
linux-kernel@vger.kernel.org, linux-nvme@lists.infradead.org,
hch@lst.de, linux-block@vger.kernel.org, dm-devel@redhat.com,
yi.zhang@redhat.com, jaegeuk@kernel.org,
linux-ext4@vger.kernel.org, gmazyland@gmail.com
Subject: Re: [dm-devel] regression: data corruption with ext4 on LUKS on nvme with torvalds master
Date: Fri, 14 May 2021 19:26:14 +0900 [thread overview]
Message-ID: <20210514102614.3804-1-nanich.lee@samsung.com> (raw)
In-Reply-To: <alpine.LRH.2.02.2105140544010.22439@file01.intranet.prod.int.rdu2.redhat.com>
> On 5/13/21 7:15 AM, Theodore Ts'o wrote:
> > On Thu, May 13, 2021 at 06:42:22PM +0900, Changheun Lee wrote:
> >>
> >> Problem might be casued by exhausting of memory. And memory exhausting
> >> would be caused by setting of small bio_max_size. Actually it was not
> >> reproduced in my VM environment at first. But, I reproduced same problem
> >> when bio_max_size is set with 8KB forced. Too many bio allocation would
> >> be occurred by setting of 8KB bio_max_size.
> >
> > Hmm... I'm not sure how to align your diagnosis with the symptoms in
> > the bug report. If we were limited by memory, that should slow down
> > the I/O, but we should still be making forward progress, no? And a
> > forced reboot should not result in data corruption, unless maybe there
>
> If you use data=writeback, data writes and journal writes are not
> synchronized. So, it may be possible that a journal write made it through,
> a data write didn't - the end result would be a file containing random
> contents that was on the disk.
>
> Changheun - do you use data=writeback? Did the corruption happen only in
> newly created files? Or did it corrupt existing files?
Actually I didn't reproduced data corruption. I only reproduced hang during
making ext4 filesystem. Alex, could you check it?
>
> > was a missing check for a failed memory allocation, causing data to be
> > written to the wrong location, a missing error check leading to the
> > block or file system layer not noticing that a write had failed
> > (although again, memory exhaustion should not lead to failed writes;
> > it might slow us down, sure, but if writes are being failed, something
> > is Badly Going Wrong --- things like writes to the swap device or
> > writes by the page cleaner must succeed, or else Things Would Go Bad
> > In A Hurry).
>
> Mikulas
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next prev parent reply other threads:[~2021-05-17 7:51 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <a01ab479-69e8-9395-7d24-9de1eec28aff@acm.org>
[not found] ` <0e7b0b6e-e78c-f22d-af8d-d7bdcb597bea@gmail.com>
2021-05-13 19:22 ` [dm-devel] regression: data corruption with ext4 on LUKS on nvme with torvalds master Mikulas Patocka
2021-05-13 21:18 ` Bart Van Assche
2021-05-14 9:43 ` Mikulas Patocka
2021-05-14 9:50 ` Mikulas Patocka
[not found] ` <CGME20210514104426epcas1p3ee2f22f8e18c961118795c356e6a14ae@epcas1p3.samsung.com>
2021-05-14 10:26 ` Changheun Lee [this message]
2021-07-09 20:45 ` Samuel Mendoza-Jonas
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