From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-13.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_IN_DEF_DKIM_WL autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6FD27C4338F for ; Wed, 4 Aug 2021 16:54:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4DB8660F94 for ; Wed, 4 Aug 2021 16:54:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239700AbhHDQym (ORCPT ); Wed, 4 Aug 2021 12:54:42 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60638 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239638AbhHDQyi (ORCPT ); Wed, 4 Aug 2021 12:54:38 -0400 Received: from mail-yb1-xb2d.google.com (mail-yb1-xb2d.google.com [IPv6:2607:f8b0:4864:20::b2d]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 95E64C061798 for ; Wed, 4 Aug 2021 09:54:25 -0700 (PDT) Received: by mail-yb1-xb2d.google.com with SMTP id k65so4771243yba.13 for ; Wed, 04 Aug 2021 09:54:25 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=yN6+s2skg1cQMKmJXP1gEppbA6Yu/yhjKK82lWQnCnM=; b=RPnPRoc8iKAsaPqqQNjqaVwHWGrkxjKMuFopfvnxvMqSsAZaeJ1wNkdFdL146W5pZv pfZnOtJt5PjrMUXAl979FTJ0LLGbQ1G5nkKu6g9VKxcAKuSiB/iSGzD5ICo7S7vTFfDr ZuwENH41eo28rKjtoBx2jwfst5bX/JJ0PR7KYfwYlggjNcKvW0azFQZZU+sv554GrDad qpxoDLz36EtxdpjcZGzJoB7btq4LqOUXofKJP831jL+rwRMraX2MfHwWYxNlGYihVSvZ MvSmK9RgZjg4hJkdpMYx08jORZEXMxhH4lwmYWwL46qQqNohfr2ZEKgfqDElhC6XIgsg CNYQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=yN6+s2skg1cQMKmJXP1gEppbA6Yu/yhjKK82lWQnCnM=; b=HtMlEJI+J+tKkItjx9+JIw2Uttd/rTXCPU5TAVwtkOnRWCeEOyYhB3AZ/Lt3SGFKl5 EnjF82/c5K6K7IblPiVkXqXiH3SRD8RljjiNksSZKafrpQN8Zq/wnOMQIGS5Iu5VlVZu 6j1fAnK9qL9+KikbwfZ7AwpHnQ+SH/JhAG2yJkdhpNoykUpmhFS3oYkQArgi5FD6fwcu 5p4Ws5uW0IUvl1iip06tCc6RBJOebSUnFncrb4UnTIeJZxFn4Ifxmrj6WLUNpcnbRmLX GSwrG7EyyTyfVWXGWSM7SG6NEf30enbgeE8X+SE8EWb94mOTXFoAA/sSNYebAYwqdHGD urjg== X-Gm-Message-State: AOAM530avo3SWW+n3cRFEzPEepc610boqWPRac5k3/mjC20TVO/+a7z3 FKEAdIb3EYr7rak9ot6vX2IMKAuwcUnKPebHKb+vvA== X-Google-Smtp-Source: ABdhPJxPn/6uYOUWAMU+RHYMsTFL8YmkD7GufT2JGUw3Tr/B220J2elCakmRm5hFcPBgL9rtDUkv+rV72fghjOYpmpM= X-Received: by 2002:a25:7ec4:: with SMTP id z187mr369533ybc.136.1628096064532; Wed, 04 Aug 2021 09:54:24 -0700 (PDT) MIME-Version: 1.0 References: <20210802221431.2251210-1-surenb@google.com> In-Reply-To: From: Suren Baghdasaryan Date: Wed, 4 Aug 2021 09:54:12 -0700 Message-ID: Subject: Re: [PATCH v4 1/2] mm: introduce process_mrelease system call To: Michal Hocko Cc: Andrew Morton , David Rientjes , Matthew Wilcox , Johannes Weiner , Roman Gushchin , Rik van Riel , Minchan Kim , Christian Brauner , Christoph Hellwig , Oleg Nesterov , David Hildenbrand , Jann Horn , Shakeel Butt , Andy Lutomirski , Christian Brauner , Florian Weimer , Jan Engelhardt , Tim Murray , Linux API , linux-mm , LKML , kernel-team Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Aug 3, 2021 at 11:21 PM Michal Hocko wrote: > > On Tue 03-08-21 15:09:43, Suren Baghdasaryan wrote: > > On Tue, Aug 3, 2021 at 10:27 AM Suren Baghdasaryan wrote: > [...] > > > > > + if (task_will_free_mem(task) && (task->flags & PF_KTHREAD) == 0) { > > > > > + mm = task->mm; > > > > > + mmget(mm); > > > > > + } > > > > > + task_unlock(task); > > > > > + if (!mm) { > > > > > > > > Do we want to treat MMF_OOM_SKIP as a failure? > > > > > > Yeah, I don't think we want to create additional contention if > > > oom-killer is already working on this mm. Should we return EBUSY in > > > this case? Other possible options is ESRCH, indicating that this > > > process is a goner, so don't bother. WDYT? > > > > After considering this some more I think ESRCH would be more > > appropriate. EBUSY might be understood as "I need to retry at a better > > time", which is not what we want here. > > Why cannot we simply return 0 in that case. The work has been done > already by the kernel so why should we tell the caller that there was > something wrong? Ah, you are right. I was under the impression that MMF_OOM_SKIP means oom-killer is reaping the mm, but looks like it means that mm was already reaped. If that's true then I agree, returning 0 is the right move here. Will fix. > > -- > Michal Hocko > SUSE Labs