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Date:   Tue, 9 Aug 2022 10:12:51 +0200
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Subject: Re: ext2/zram issue [was: Linux 5.19]
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From:   Jiri Slaby <jirislaby@kernel.org>
To:     Linus Torvalds <torvalds@linux-foundation.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Cc:     minchan@kernel.org, ngupta@vflare.org,
        Sergey Senozhatsky <senozhatsky@chromium.org>,
        Jan Kara <jack@suse.com>, Ted Ts'o <tytso@mit.edu>,
        Andreas Dilger <adilger.kernel@dilger.ca>,
        Ext4 Developers List <linux-ext4@vger.kernel.org>,
        avromanov@sberdevices.ru, ddrokosov@sberdevices.ru
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On 09. 08. 22, 9:59, Jiri Slaby wrote:
> Ah, now I can. It's easy when one lowers memory available to qemu. -m 
> 800M in this case:
> echo $((1000*1024*1024)) > /sys/block/zram0/disksize
> mkfs.ext2 /dev/zram0
> mount /dev/zram0 /mnt/a/
> dd if=/dev/urandom of=/mnt/a/stuff
> [  200.334277][    T8] EXT4-fs warning (device zram0): ext4_end_bio:343: 
> I/O error 10 writing to inode 12 starting block 8192)
> [  200.340198][    T8] Buffer I/O error on device zram0, logical block 8192
> 
> 
> So currently, I blame:
> commit e7be8d1dd983156bbdd22c0319b71119a8fbb697
> Author: Alexey Romanov <avromanov@sberdevices.ru>
> Date:   Thu May 12 20:23:07 2022 -0700
> 
>      zram: remove double compression logic
> 
> 
> /me needs to confirm.

With that commit reverted, I see no more I/O errors, only oom-killer 
messages (which is OK IMO, provided I write 1G of urandom on a machine 
w/ 800M of RAM):
[   30.424603][  T728] dd invoked oom-killer: 
gfp_mask=0x140cca(GFP_HIGHUSER_MOVABLE|__GFP_COMP), order=0, oom_score_adj=0

Now let me submit it to openQA too...

thanks,
-- 
js
suse labs