linux-kernel - Re: [PATCH v6 6/6] zsmalloc: Implement writeback mechanism for zsmalloc

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Message-ID: <Y3x38acHBZkWQbL7@google.com>
Date:   Tue, 22 Nov 2022 16:19:13 +0900
From:   Sergey Senozhatsky <senozhatsky@...omium.org>
To:     Johannes Weiner <hannes@...xchg.org>
Cc:     Sergey Senozhatsky <senozhatsky@...omium.org>,
        Nhat Pham <nphamcs@...il.com>, akpm@...ux-foundation.org,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        minchan@...nel.org, ngupta@...are.org, sjenning@...hat.com,
        ddstreet@...e.org, vitaly.wool@...sulko.com
Subject: Re: [PATCH v6 6/6] zsmalloc: Implement writeback mechanism for
 zsmalloc

On (22/11/22 02:10), Johannes Weiner wrote:
> > Yes. "What if it would continue". Would it make sense to not
> > break on EAGAIN?
> > 
> > 	while (total < pages) {
> > 		ret = zs_reclaim_page(pool);
> > 		if (ret == -EAGAIN)
> > 			continue;
> > 		if (ret < 0)
> > 			break;
> > 		total++;
> > 	}
> > 
> > Then we don't need retry loop in zs_reclaim_page().
> 
> But that's an indefinite busy-loop?

That would mean that all lru pages constantly have locked objects
and we can only make partial progress.

> I don't see what the problem with limited retrying in
> zs_reclaim_page() is. It's robust and has worked for years.

No problem with it, just asking.