linux-kernel - Re: [PATCH v3 6/8] workingset: memcg: sleep when flushing stats in workingset

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Message-ID: <20230405080047.5omnatjbwz46f3y5@blackpad>
Date:   Wed, 5 Apr 2023 10:00:47 +0200
From:   Michal Koutný <mkoutny@...e.com>
To:     Yosry Ahmed <yosryahmed@...gle.com>
Cc:     Tejun Heo <tj@...nel.org>, Josef Bacik <josef@...icpanda.com>,
        Jens Axboe <axboe@...nel.dk>,
        Zefan Li <lizefan.x@...edance.com>,
        Johannes Weiner <hannes@...xchg.org>,
        Michal Hocko <mhocko@...nel.org>,
        Roman Gushchin <roman.gushchin@...ux.dev>,
        Shakeel Butt <shakeelb@...gle.com>,
        Muchun Song <muchun.song@...ux.dev>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Vasily Averin <vasily.averin@...ux.dev>,
        cgroups@...r.kernel.org, linux-block@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        bpf@...r.kernel.org, Michal Hocko <mhocko@...e.com>
Subject: Re: [PATCH v3 6/8] workingset: memcg: sleep when flushing stats in
 workingset_refault()

On Tue, Apr 04, 2023 at 11:09:02AM -0700, Yosry Ahmed <yosryahmed@...gle.com> wrote:
> IIUC there are multiple places where we can sleep in this path, we can
> sleep waiting for a page to be read from disk, we can sleep during
> allocating the page to read into, and IIUC the allocations on the
> fault path can even run into reclaim, going into the vmscan code. So
> there are precedents, but I am not sure if that's enough argument.

I expect it'd depend on the proportion of the slow/fast paths.
OK, let's see how it turns out in wider population.

Thanks,
Michal

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