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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0D141C433EF for ; Tue, 23 Nov 2021 17:28:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239261AbhKWRb7 (ORCPT ); Tue, 23 Nov 2021 12:31:59 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49240 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239281AbhKWRb4 (ORCPT ); Tue, 23 Nov 2021 12:31:56 -0500 Received: from mail-lf1-x133.google.com (mail-lf1-x133.google.com [IPv6:2a00:1450:4864:20::133]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 79D75C06173E for ; Tue, 23 Nov 2021 09:28:47 -0800 (PST) Received: by mail-lf1-x133.google.com with SMTP id n12so17917lfe.1 for ; Tue, 23 Nov 2021 09:28:47 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=0VQ/DXnMuEbx26lUPiWfkgXYKbsUMBeuhoLEdn1uwPY=; b=LjjIQiSAWqZ2g0LZZgrpgKZfI5OfBDS1vwZklGguJ7PGH9V/pvMAh4r5lAyFthu4EB Yo91sS5li38g/GvU5hE6NVpdFO3h0lq71jPgOPtozZRfYb1DfLmU8Z8MoVblkuGZb4aE umbqVrKyk1aDwEb772YUahRG9IkKUnK8y3tvzZf1OVOQg6my5h/21Y1IQ26cfN1CDWAk mNlFpZ+IT3DFTYRzyrZ5pNMIxbayTF5gIBGUVpOmQyk/0YX9pMUMKhyW7iEvua9S7hcA cI0HLDAeVPmkHe7vSXzPeKk3O7VK8McFSqUnsIr4l9b143K4wDyb8wP/IgJpaUf/xAck 7Zjw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=0VQ/DXnMuEbx26lUPiWfkgXYKbsUMBeuhoLEdn1uwPY=; b=u/UVLc3DWVw5AEsjoL+2w/odE9C8IjqB9bAQ5eBmzExfb0G56Hvu4iNfXxwIKb4VCK yGvauD98aQbTQMQEgt2o/PB8UoBO0A3Tjy2HLes1LcozmrQX9uDHisk7QH3G19VcFPS4 bXbJ2y8i/341uWgh7NFpGORzc8Jg5jyy0f5Z8k2F77a97NQRfVO90EkAhAPYAwDnZvgQ BJTkBhzNVupvLqxlDqDspuxOqRWEe90JGNUGf8zkJ+mZGasrVcjibjZUW5k12Wu3l7EX 0AjlOezv8WlfzzcwVymmp+k0mhE6lmyKwd5VGWGhLhkd0LMwXj+l7De14yNvE/GXAcxt Ec1g== X-Gm-Message-State: AOAM532+ztS4sRdgbWRNWFNa+j2bjd+yJIqNkebx37w+4OV1nxAGew7n NmFHJiKrZOPKgTtLe0IJZIDzTSfr047yL6pAw2Bz1Q== X-Google-Smtp-Source: ABdhPJysD3LJp3obeHCcm6LaJbNT1NkcWYlv//jXgDLA2+KIrlDxanfCBMwXcLRyTJlpwDA8uvDhaNJKLOFm9MdGHls= X-Received: by 2002:ac2:4d0a:: with SMTP id r10mr6444054lfi.210.1637688525482; Tue, 23 Nov 2021 09:28:45 -0800 (PST) MIME-Version: 1.0 References: <20211120201230.920082-1-shakeelb@google.com> <25b36a5c-5bbd-5423-0c67-05cd6c1432a7@redhat.com> <1b30d06d-f9c0-1737-13e6-2d1a7d7b8507@redhat.com> <92fe0c31-b083-28c4-d306-da8a3cd891a3@redhat.com> <1b400921-8bef-8073-10f9-a7cbb09cfefe@redhat.com> In-Reply-To: <1b400921-8bef-8073-10f9-a7cbb09cfefe@redhat.com> From: Shakeel Butt Date: Tue, 23 Nov 2021 09:28:34 -0800 Message-ID: Subject: Re: [PATCH] mm: split thp synchronously on MADV_DONTNEED To: David Hildenbrand Cc: "Kirill A . Shutemov" , Yang Shi , Zi Yan , Matthew Wilcox , Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Nov 23, 2021 at 9:26 AM David Hildenbrand wrote: > > On 23.11.21 18:24, Shakeel Butt wrote: > > On Tue, Nov 23, 2021 at 9:20 AM David Hildenbrand wrote: > >> > >> On 23.11.21 18:17, Shakeel Butt wrote: > >>> On Tue, Nov 23, 2021 at 8:57 AM David Hildenbrand wrote: > >>>> > >>> [...] > >>>>>> > >>>>>> I do wonder which these locking contexts are exactly, and if we could > >>>>>> also do the same thing on ordinary munmap -- because I assume it can be > >>>>>> similarly problematic for some applications. > >>>>> > >>>>> This is a good question regarding munmap. One main difference is > >>>>> munmap takes mmap_lock in write mode and usually performance critical > >>>>> applications avoid such operations. > >>>> > >>>> Maybe we can extend it too most page zapping, if that makes things simpler. > >>>> > >>> > >>> Do you mean doing sync THP split for most of page zapping functions > >>> (but only if that makes things simpler)? > >>> > >> > >> Yes -- if there are no downsides. > >> > > > > I will try. At the moment the assumption of "Not null zap_details > > implies leave swap entries" is giving me a headache. > > Not only you, did you stumble over > > https://lkml.kernel.org/r/20211115134951.85286-1-peterx@redhat.com > > already? > Oh thanks for the pointer. I missed that. I will take a look. Thanks again.