linux-kernel - Re: [PATCH] mm: ratelimit end_swap_bio

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Date:   Mon, 8 Jan 2018 10:58:18 +0900
From:   Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
To:     Michal Hocko <mhocko@...nel.org>
Cc:     Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>,
        Minchan Kim <minchan@...nel.org>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mm: ratelimit end_swap_bio_write() error

On (01/06/18 14:34), Michal Hocko wrote:
> > zsmalloc allocation is just one possibility; an error in
> > compressing algorithm is another one, yet is rather unlikely.
> > most likely it's OOM which can cause problems. but in any case
> > it's sort of unclear what should be done. an error can be a
> > temporary one or a fatal one, just like in __swap_writepage()
> > case. so may be both write error printk()-s can be dropped.
> 
> Then I would suggest starting with sorting out which of those errors are
> critical and which are not and report the error accordingly. I am sorry
> to be fuzzy here but I am not familiar with the code to be more
> specific. Anyway ratelimiting sounds more like a paper over than a real
> solution. Also it sounds quite scary that you can see so many failures
> to actually lock up the system just by printing a message...

the lockup is not the main problem and I'm not really trying to
address it here. we simply can fill up the entire kernel logbuf
with the same "Write-error on swap-device" errors.

	-ss