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 6D612C433F5 for ; Tue, 8 Mar 2022 00:59:41 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id CE3B08D0002; Mon, 7 Mar 2022 19:59:40 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id C929F8D0001; Mon, 7 Mar 2022 19:59:40 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id B32E08D0002; Mon, 7 Mar 2022 19:59:40 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0249.hostedemail.com [216.40.44.249]) by kanga.kvack.org (Postfix) with ESMTP id A4E728D0001 for ; Mon, 7 Mar 2022 19:59:40 -0500 (EST) Received: from smtpin29.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 3E5E518288A5E for ; Tue, 8 Mar 2022 00:59:40 +0000 (UTC) X-FDA: 79219411320.29.72402C0 Received: from mail-pj1-f43.google.com (mail-pj1-f43.google.com [209.85.216.43]) by imf31.hostedemail.com (Postfix) with ESMTP id BEFD120002 for ; Tue, 8 Mar 2022 00:59:39 +0000 (UTC) Received: by mail-pj1-f43.google.com with SMTP id ge19-20020a17090b0e1300b001bcca16e2e7so763033pjb.3 for ; Mon, 07 Mar 2022 16:59:39 -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=xtN9yLTb/VZCQMriln/ieL7U3maXDlCZhw7+/x2Xd10=; b=kWJbaJfnC0JDoYimBwsSOto5UcIg5mJnsY6qxfTPBsNjiH2w1G5NxXKodifNnqltja sxBnvWB4V4FAWJXxEgFeFhsutPb5156Mq1zlkWBTsBsj/AS2Cu256gmqEEDshX5+KtV6 +8v5eJ5I3LL8/4rg81rOfunj/sx0fFyqzgOu580RV+GtYWcPGR+H4PSBlXTtsFDt3E57 SQ3Ga8/3YTi/ufb/1eITkEjw3P1ZWo5dmfG/olKbkS/KFwvKZ96oGcE6rRE0hx2DuKtm 0lT2pJuTLwNMJM1eM6+JZNadOOfE91LS/favvKQLY3snFxvJV7hgFdTCZcEcSNvwZaRt i3Bg== 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=xtN9yLTb/VZCQMriln/ieL7U3maXDlCZhw7+/x2Xd10=; b=v+zifUDTYGYwNfJQWGrYPaismFQ9hvuGXtLKUSmsX5OOJNIEEy+Hh6LYF3vxOgW/hq Og+48yB37D1VFsiLm7AT7GzJfibxeSn83ssqdWyJkaYxgmOoOIdlthyvPMOx0KFVHHdB nBxL0kZUyzY+kZb9Lu9Pr23nGRonq3HxZb7dCYS4LCZWbZgewgTHoPjjcABSdeRFTuwY 1hY+z3b10vez5ilZcAMCKtRBAqAUS6bq/dBTWd9E1D9yQtWFoZGx62/IGwFtNsIzQjRO 5o3Zff2LkI73lWAYcZ2iWYwAdxKS6mvBdMvNR299uyGwB0ZphnvKAgnQNEmJCdF06QcP PnYw== X-Gm-Message-State: AOAM533nZCUJ7Qf0eZyO7ROngAetB0U0JE6fRhRuHBz4ACBPVNLQlkVO KJq198HChDlL+ctDjy4lRtF3hCS2B0CRfBVTb84= X-Google-Smtp-Source: ABdhPJy3/4uzjpeSlfbyOXX5UtMgEdRa+7VpX8bfuIbEafQh+pPDwE6yq08SMaeOqwsaSJBeRZvA43BPFw2ucMqqJvA= X-Received: by 2002:a17:90b:1b0e:b0:1bf:1c4f:2bc4 with SMTP id nu14-20020a17090b1b0e00b001bf1c4f2bc4mr1846234pjb.200.1646701178737; Mon, 07 Mar 2022 16:59:38 -0800 (PST) MIME-Version: 1.0 References: <20220303222014.517033-1-shy828301@gmail.com> <13ad4ba1-2a88-9459-3995-70af36aba33e@redhat.com> <20220306180718.6d4e6233130b94fdad98df88@linux-foundation.org> <84a6c9c1-d18f-6955-2666-0a2d7bce6094@redhat.com> <20220307154326.6494f7fca7def491a23e5df1@linux-foundation.org> <20220307165015.77fbcbe9e1fa2fe15f3eb239@linux-foundation.org> In-Reply-To: <20220307165015.77fbcbe9e1fa2fe15f3eb239@linux-foundation.org> From: Yang Shi Date: Mon, 7 Mar 2022 16:59:27 -0800 Message-ID: Subject: Re: [PATCH] mm: thp: don't have to lock page anymore when splitting PMD To: Andrew Morton Cc: David Hildenbrand , Andrea Arcangeli , Hugh Dickins , "Kirill A. Shutemov" , Linux Kernel Mailing List , Linux MM , Matthew Wilcox Content-Type: text/plain; charset="UTF-8" X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: BEFD120002 X-Stat-Signature: 53ehkh1b9ts8qpxxc4tcmdmypg4qfsg7 Authentication-Results: imf31.hostedemail.com; dkim=pass header.d=gmail.com header.s=20210112 header.b=kWJbaJfn; spf=pass (imf31.hostedemail.com: domain of shy828301@gmail.com designates 209.85.216.43 as permitted sender) smtp.mailfrom=shy828301@gmail.com; dmarc=pass (policy=none) header.from=gmail.com X-HE-Tag: 1646701179-906082 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 Mon, Mar 7, 2022 at 4:50 PM Andrew Morton wrote: > > On Mon, 7 Mar 2022 16:03:12 -0800 Yang Shi wrote: > > > On Mon, Mar 7, 2022 at 3:43 PM Andrew Morton wrote: > > > @@ -2133,8 +2133,6 @@ void __split_huge_pmd(struct vm_area_str > > > { > > > spinlock_t *ptl; > > > struct mmu_notifier_range range; > > > - bool do_unlock_folio = false; > > > - pmd_t _pmd; > > > > > > mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm, > > > address & HPAGE_PMD_MASK, > > > @@ -2153,42 +2151,14 @@ void __split_huge_pmd(struct vm_area_str > > > goto out; > > > } > > > > > > -repeat: > > > if (pmd_trans_huge(*pmd)) { > > > - if (!folio) { > > > + if (!folio) > > > folio = page_folio(pmd_page(*pmd)); > > > > We could remove the "if (pmd_trans_huge(*pmd))" section since folio is > > actually not used afterward at all. > > > > > ... > > > > > > With the above if removed, this could be changed to: > > > > if (pmd_trans_huge(*pmd) || pmd_devmap(*pmd) || > > is_pmd_migration_entry(*pmd)) > > __split_huge_pmd_locked(vma, pmd, range.start, freeze); > > > > OK, looks sane. Can someone please test all this? Build test? I had the exact same change in my tree, it worked for me. > > --- a/mm/huge_memory.c~mm-huge_memory-remove-stale-locking-logic-from-__split_huge_pmd-fix > +++ a/mm/huge_memory.c > @@ -2151,12 +2151,10 @@ void __split_huge_pmd(struct vm_area_str > goto out; > } > > - if (pmd_trans_huge(*pmd)) { > - if (!folio) > - folio = page_folio(pmd_page(*pmd)); > - } else if (!(pmd_devmap(*pmd) || is_pmd_migration_entry(*pmd))) > - goto out; > - __split_huge_pmd_locked(vma, pmd, range.start, freeze); > + if (pmd_trans_huge(*pmd) || pmd_devmap(*pmd) || > + is_pmd_migration_entry(*pmd))) > + __split_huge_pmd_locked(vma, pmd, range.start, freeze); > + > out: > spin_unlock(ptl); > /* > _ >