linux-kernel - Re: [PATCH 1/1] mm: introduce process

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Date:   Thu, 08 Jul 2021 09:13:48 +0200
From:   Florian Weimer <fweimer@...hat.com>
To:     Suren Baghdasaryan <surenb@...gle.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Michal Hocko <mhocko@...nel.org>,
        Michal Hocko <mhocko@...e.com>,
        David Rientjes <rientjes@...gle.com>,
        Matthew Wilcox <willy@...radead.org>,
        Johannes Weiner <hannes@...xchg.org>,
        Roman Gushchin <guro@...com>, Rik van Riel <riel@...riel.com>,
        Minchan Kim <minchan@...nel.org>,
        Christian Brauner <christian@...uner.io>,
        Christoph Hellwig <hch@...radead.org>,
        Oleg Nesterov <oleg@...hat.com>,
        David Hildenbrand <david@...hat.com>,
        Jann Horn <jannh@...gle.com>,
        Shakeel Butt <shakeelb@...gle.com>,
        Tim Murray <timmurray@...gle.com>,
        Linux API <linux-api@...r.kernel.org>,
        linux-mm <linux-mm@...ck.org>,
        LKML <linux-kernel@...r.kernel.org>,
        kernel-team <kernel-team@...roid.com>
Subject: Re: [PATCH 1/1] mm: introduce process_reap system call

* Suren Baghdasaryan:

> Sending SIGKILL is blocking in terms of delivering the signal, but it
> does not block waiting for SIGKILL to be processed by the signal
> recipient and memory to be released. When I was talking about
> "blocking", I meant that current kill() and friends do not block to
> wait for SIGKILL to be processed.
> process_reap() will block until the memory is released. Whether the
> userspace caller is using it right after sending a SIGKILL to reclaim
> the memory synchronously or spawns a separate thread to reclaim memory
> asynchronously is up to the user. Both patterns are supported.

I see, this makes sense.

Considering that the pidfd sticks around after process_reap returns, the
issue described in bug 154011 probably does not apply to process_reap.
(This relates to asynchronous resource deallocation, as discussed before.)

Thanks,
Florian