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=-6.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS 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 ED464C433E2 for ; Tue, 1 Sep 2020 15:57:30 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 9FD2D206EB for ; Tue, 1 Sep 2020 15:57:30 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="R5Ah/xy7" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9FD2D206EB Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 176966B0075; Tue, 1 Sep 2020 11:57:30 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 12817900010; Tue, 1 Sep 2020 11:57:30 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 03DFE6B007D; Tue, 1 Sep 2020 11:57:30 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0184.hostedemail.com [216.40.44.184]) by kanga.kvack.org (Postfix) with ESMTP id E38AD6B0075 for ; Tue, 1 Sep 2020 11:57:29 -0400 (EDT) Received: from smtpin13.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id A2476180AD801 for ; Tue, 1 Sep 2020 15:57:29 +0000 (UTC) X-FDA: 77214947418.13.space95_0f08b5327099 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin13.hostedemail.com (Postfix) with ESMTP id 75A9C18140B67 for ; Tue, 1 Sep 2020 15:57:29 +0000 (UTC) X-HE-Tag: space95_0f08b5327099 X-Filterd-Recvd-Size: 5903 Received: from mail-ej1-f68.google.com (mail-ej1-f68.google.com [209.85.218.68]) by imf29.hostedemail.com (Postfix) with ESMTP for ; Tue, 1 Sep 2020 15:57:28 +0000 (UTC) Received: by mail-ej1-f68.google.com with SMTP id m22so2371648eje.10 for ; Tue, 01 Sep 2020 08:57:28 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=Ja1Ngj7NH47x40mFJlmmy6/fspeTMYwfVXDFlvDZIns=; b=R5Ah/xy7z0CYa/cOPWoKydl55+5AZx0X0xQJSi7oXsefEDGnUWoEmUvrBgHDB6qi9M /0BqPFsX1uD16ZqQrlqlFY/brxotDPaHIoOx5hvvLGC7lSE/Rn1VXNwev5SZpYADEWZW xGNROhES6O3tp7K9FtFb1rbn1WTcgV36Lmdx4vC4Z9L++ntjEsM9CkS30Xkv7gD8IL23 xj71aaX3htYZQSlf+C1O1oREaf7eGZp+A5SifAfa3S5foT+pHlv7zElngZUgc2r/DNbI 3ceu3otruVt5OiOnce89EX+sGUkJIuxUfOEGdYo8PjqYYHV/c0UHcQUPFJI8vhhJiyUW Uyvw== 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=Ja1Ngj7NH47x40mFJlmmy6/fspeTMYwfVXDFlvDZIns=; b=WbeSb0beho/8kFlYU5kYDD9x5jGOv1Z2Mzm+NBEtk2xSckBjd2bbj+CqH5fu1g0E9h ArpyGnVWhO6PjruoZbS9p+z/trxMPZHhekeLV5iRMVOmOty9eq6aBv+o/kVLEZy987ru PCXu7VBFWfJuOEUFnO93+/v4vtIdB2fg91LJUFQvqxlIdZhrzLOVI0p+MLf63oGksp8h FNbbGjdZLZEaqtb4W/QljS35+NwuU05E1Q0B9EGcHOZo6V0W1NoaWEm5xJePCney/TZ4 nM9jW+glpsQeyZzIe8ktXBTd44ZghDvPBeJUQoNvTC9xOKahJDeFW1NwUL7gT5sVlzIQ Sn9A== X-Gm-Message-State: AOAM532dfSb11f8RLIF0Zuj82O/pCAPgvC+GbvW9eJW+Z8Gm+Mj6db6c zC8xPwyl2mQd2fOdFnns06v9sXSn4VseIckAvWk= X-Google-Smtp-Source: ABdhPJyuNoXmSK9kdaNb5NJmH/3HsU8fUsgYikM66A4Np4f+RaqiTJn5bkqn7polwbuP2ipcbL+X4LqpsmkGVqFyETs= X-Received: by 2002:a17:906:edd6:: with SMTP id sb22mr1911092ejb.499.1598975847689; Tue, 01 Sep 2020 08:57:27 -0700 (PDT) MIME-Version: 1.0 References: In-Reply-To: From: Yang Shi Date: Tue, 1 Sep 2020 08:57:15 -0700 Message-ID: Subject: Re: [PATCH 4/5] mm: fix check_move_unevictable_pages() on THP To: Hugh Dickins Cc: Andrew Morton , Alex Shi , Johannes Weiner , Michal Hocko , Mike Kravetz , Shakeel Butt , Matthew Wilcox , Qian Cai , Chris Wilson , Kuo-Hsin Yang , Linux Kernel Mailing List , Linux MM Content-Type: text/plain; charset="UTF-8" X-Rspamd-Queue-Id: 75A9C18140B67 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam04 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 Sun, Aug 30, 2020 at 2:08 PM Hugh Dickins wrote: > > check_move_unevictable_pages() is used in making unevictable shmem pages > evictable: by shmem_unlock_mapping(), drm_gem_check_release_pagevec() and > i915/gem check_release_pagevec(). Those may pass down subpages of a huge > page, when /sys/kernel/mm/transparent_hugepage/shmem_enabled is "force". > > That does not crash or warn at present, but the accounting of vmstats > unevictable_pgs_scanned and unevictable_pgs_rescued is inconsistent: > scanned being incremented on each subpage, rescued only on the head > (since tails already appear evictable once the head has been updated). > > 5.8 commit 5d91f31faf8e ("mm: swap: fix vmstats for huge page") has > established that vm_events in general (and unevictable_pgs_rescued in > particular) should count every subpage: so follow that precedent here. > > Do this in such a way that if mem_cgroup_page_lruvec() is made stricter > (to check page->mem_cgroup is always set), no problem: skip the tails > before calling it, and add thp_nr_pages() to vmstats on the head. > > Signed-off-by: Hugh Dickins Acked-by: Yang Shi > --- > Nothing here worth going to stable, since it's just a testing config > that is fixed, whose event numbers are not very important; but this > will be needed before Alex Shi's warning, and might as well go in now. > > The callers of check_move_unevictable_pages() could be optimized, > to skip over tails: but Matthew Wilcox has other changes in flight > there, so let's skip the optimization for now. > > mm/vmscan.c | 10 ++++++++-- > 1 file changed, 8 insertions(+), 2 deletions(-) > > --- 5.9-rc2/mm/vmscan.c 2020-08-16 17:32:50.721507348 -0700 > +++ linux/mm/vmscan.c 2020-08-28 17:47:10.595580876 -0700 > @@ -4260,8 +4260,14 @@ void check_move_unevictable_pages(struct > for (i = 0; i < pvec->nr; i++) { > struct page *page = pvec->pages[i]; > struct pglist_data *pagepgdat = page_pgdat(page); > + int nr_pages; > + > + if (PageTransTail(page)) > + continue; > + > + nr_pages = thp_nr_pages(page); > + pgscanned += nr_pages; > > - pgscanned++; > if (pagepgdat != pgdat) { > if (pgdat) > spin_unlock_irq(&pgdat->lru_lock); > @@ -4280,7 +4286,7 @@ void check_move_unevictable_pages(struct > ClearPageUnevictable(page); > del_page_from_lru_list(page, lruvec, LRU_UNEVICTABLE); > add_page_to_lru_list(page, lruvec, lru); > - pgrescued++; > + pgrescued += nr_pages; > } > } > >