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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 283DEC433EF for ; Wed, 24 Nov 2021 21:17:47 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 82F176B0075; Wed, 24 Nov 2021 16:17:31 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 7B7A06B0078; Wed, 24 Nov 2021 16:17:31 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 658A46B007B; Wed, 24 Nov 2021 16:17:31 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0159.hostedemail.com [216.40.44.159]) by kanga.kvack.org (Postfix) with ESMTP id 580446B0075 for ; Wed, 24 Nov 2021 16:17:31 -0500 (EST) Received: from smtpin10.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 1E0AB181A349C for ; Wed, 24 Nov 2021 21:17:21 +0000 (UTC) X-FDA: 78845084724.10.7A2B895 Received: from mail-ed1-f49.google.com (mail-ed1-f49.google.com [209.85.208.49]) by imf15.hostedemail.com (Postfix) with ESMTP id 21709D0000AA for ; Wed, 24 Nov 2021 21:17:15 +0000 (UTC) Received: by mail-ed1-f49.google.com with SMTP id g14so16248029edb.8 for ; Wed, 24 Nov 2021 13:17:20 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=oI7l8M/MEztUdZBSwfddwsly9qSkYWDc6QESfM+2LzA=; b=AG3W+5L1wMKmjV6RP8hADtwGPbtJ+WMtO9Unm4Jp9JnSa7MVLiXBig+JddU7A0oE2P cd7S8Ym5IYrJRRDxOvACxqY2Q6XeI6/ys13O+ryiL/LHu+aiu5WGDBxszxAZSGtpTLYg mAGP28JGxHCvEkDaA7840eh9zO+L5VgJyoENEzn00qtwB3epRmfsgJWcWgdXjIiyoibo tEEjBLijWoMvmAHSxp507eHBA/uFvZoebb5lI9Qv2/4NJfTgePy3+Bp2bCtN/rvCPDaS Mei6xZTlLOZT+dhox3h9Ady5zPqSsnbU9jIQY5jNRV9Pj3cBqR2TKPEZKurSRS4kXl+E QtEQ== 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=oI7l8M/MEztUdZBSwfddwsly9qSkYWDc6QESfM+2LzA=; b=Gcz1TbwADfykMVWxuW2hoOjB1FampP3MHH8+DPEI8uJ+GxVx2xSGP1KzHgSRjdUGov tCCMQJi/kMK+dIabd+25bgoAz9bwbplD8ZG62WjrqXKGxRHAyxuvEjypftMZ1jKdMZty wd3AJh7ayB9znh4u90OYnnZyiqHCqBUKVUAUwOwd2TcYkXfs/gezZPuxO6ZJ0MinIXdl sBZJahQ+N2Mp2rTYKkvAfT/Mow2+ln4x2958Kvfder/Bk8uJxXiNBvlOrLfNzKLQmstz QY+caODS6OlpuiKmzTO9PZ3IWjv4iaLndQxBegf5Mo0uQ2TPjTZJ6B8TIzXSTCAPTtxJ bt2g== X-Gm-Message-State: AOAM531nlzkb9doaDF16y2/LzzwEGQNCDxhEM3Z+XnYcZs8zVJtYQzVP XpYD9KlqMGD8p9vDVVJxOpj6j/SdlIZIw9/8l+A= X-Google-Smtp-Source: ABdhPJyAItHMNcckUspIZ+8HMmX9FtNJ7te1nmG1ApEaJwryCCwwvMdgqwUMolD/OIxXtkExonVhuEAkf/AYUiHJoWo= X-Received: by 2002:a05:6402:510e:: with SMTP id m14mr30782968edd.312.1637788639370; Wed, 24 Nov 2021 13:17:19 -0800 (PST) MIME-Version: 1.0 References: <20211123190916.1738458-1-shakeelb@google.com> <20211124201238.3xzpy2b5zcv7j23s@box.shutemov.name> In-Reply-To: From: Yang Shi Date: Wed, 24 Nov 2021 13:17:07 -0800 Message-ID: Subject: Re: [PATCH v2] mm: thp: update split_queue_len correctly To: Shakeel Butt Cc: "Kirill A. Shutemov" , David Hildenbrand , "Kirill A . Shutemov" , Zi Yan , Matthew Wilcox , Andrew Morton , Linux MM , Linux Kernel Mailing List Content-Type: text/plain; charset="UTF-8" X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 21709D0000AA X-Stat-Signature: 87prgwk1amqwo4gqg9tjh643cchayh9a Authentication-Results: imf15.hostedemail.com; dkim=pass header.d=gmail.com header.s=20210112 header.b=AG3W+5L1; dmarc=pass (policy=none) header.from=gmail.com; spf=pass (imf15.hostedemail.com: domain of shy828301@gmail.com designates 209.85.208.49 as permitted sender) smtp.mailfrom=shy828301@gmail.com X-HE-Tag: 1637788635-642684 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Wed, Nov 24, 2021 at 12:44 PM Shakeel Butt wrote: > > On Wed, Nov 24, 2021 at 12:12 PM Kirill A. Shutemov > wrote: > > > > On Tue, Nov 23, 2021 at 11:09:16AM -0800, Shakeel Butt wrote: > > > The deferred THPs are split on memory pressure through shrinker > > > callback and splitting of THP during reclaim can fail for several > > > reasons like unable to lock the THP, under writeback or unexpected > > > number of pins on the THP. Such pages are put back on the deferred split > > > list for consideration later. However kernel does not update the > > > deferred queue size on putting back the pages whose split was failed. > > > This patch fixes that. > > > > Hm. No. split_huge_page_to_list() updates the queue size on split success. > > > > Right. This is really convoluted. split_huge_page_to_list() is just > assuming that if the given page is on a deferred list then it must be > on the list returned by get_deferred_split_queue(page). The > interaction of move_charge and deferred split seems broken. Because memcg code doesn't move charge for PTE mapped THP at all. See the below comment from mem_cgroup_move_charge_pte_range(): "We can have a part of the split pmd here. Moving it can be done but it would be too convoluted so simply ignore such a partial THP and keep it in original memcg. There should be somebody mapping the head." BTW, did you run into any problem related to this? > > Andrew, can you please drop this patch?