linux-kernel - Re: [PATCH 0/1] Possible bug in zram on ppc64le on vfat

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Message-ID: <Y4WMxqyVlAt0Sp3g@google.com>
Date:   Tue, 29 Nov 2022 13:38:30 +0900
From:   Sergey Senozhatsky <senozhatsky@...omium.org>
To:     Petr Vorel <pvorel@...e.cz>
Cc:     Martin Doucha <mdoucha@...e.cz>,
        Sergey Senozhatsky <senozhatsky@...omium.org>,
        Minchan Kim <minchan@...nel.org>, ltp@...ts.linux.it,
        linux-block@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-kselftest@...r.kernel.org, Nitin Gupta <ngupta@...are.org>,
        Jens Axboe <axboe@...nel.dk>,
        OGAWA Hirofumi <hirofumi@...l.parknet.co.jp>,
        Yang Xu <xuyang2018.jy@...itsu.com>
Subject: Re: [PATCH 0/1] Possible bug in zram on ppc64le on vfat

On (22/11/22 16:07), Petr Vorel wrote:
> > On 11. 11. 22 1:48, Sergey Senozhatsky wrote:
> > > On (22/11/10 15:29), Martin Doucha wrote:

[..]

> > > Can you try using /dev/urandom for dd, not /dev/zero?
> > > Do you still see zeroes in sysfs output or some random values?
> 
> > After 50 test runs on a kernel where the issue is confirmed, I could not
> > reproduce the failure while filling the device from /dev/urandom instead of
> > /dev/zero. The test reported compression ratio around 1.8-2.5 which means
> > the memory usage reported by mm_stat was 10-13MB.
> 
> Martin, thanks a lot for reruning tests. I wonder problems on /dev/zero is a
> kernel bug or just problem which should be workarounded.

Hmm. Does CONFIG_KASAN show anything interesting?