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=-12.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable 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 18F53C433DB for ; Tue, 30 Mar 2021 16:42:17 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 8E38A619CA for ; Tue, 30 Mar 2021 16:42:16 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8E38A619CA 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 0A7906B0081; Tue, 30 Mar 2021 12:42:16 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 058AB6B0082; Tue, 30 Mar 2021 12:42:16 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id E3A756B0083; Tue, 30 Mar 2021 12:42:15 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0097.hostedemail.com [216.40.44.97]) by kanga.kvack.org (Postfix) with ESMTP id CA21D6B0081 for ; Tue, 30 Mar 2021 12:42:15 -0400 (EDT) Received: from smtpin35.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id 7DF9D181AEF32 for ; Tue, 30 Mar 2021 16:42:15 +0000 (UTC) X-FDA: 77977108230.35.A2FC87A Received: from mail-ed1-f50.google.com (mail-ed1-f50.google.com [209.85.208.50]) by imf11.hostedemail.com (Postfix) with ESMTP id EC14320007C7 for ; Tue, 30 Mar 2021 16:42:03 +0000 (UTC) Received: by mail-ed1-f50.google.com with SMTP id dm8so18988351edb.2 for ; Tue, 30 Mar 2021 09:42:09 -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=tb1iiWaE4NYfh8qMRuLct9CC/jvF2xlsJa5BguwsPYc=; b=HmXrspowOmFkqTO6GyLVRZ/0IYeywcjYLrET9yDo3B6x+GI5nAcYaAgXkFrg2+ORlg qAD3HkbBo40pWwfDlPcJwlZqoXMAr2aTPi9u+T9iN0kti+jW86OMfyjuykUHZchpVUkz lAwX898XL466Le7KPtVCmwHicyyt22tXUnmKeqqYHqT5H0uJkE05lL4ktYixDB9c4tF1 FYx0jfcel8ZC8LQij9K3KUxuxTlgdnR6Pk7+RUTAQzLNhFltu8RtQ1J6nO/uVDTIoMgz TtOIdWjw9pbxsH107tZiq0d+BpI/vR4fBTr+Wk3NaVrydjgDxsQpEgOLANaZB4vNd0N3 U/ow== 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=tb1iiWaE4NYfh8qMRuLct9CC/jvF2xlsJa5BguwsPYc=; b=jV9Bv7ItOelCh4YbpGocRE91VyfGjn16iGBK0D9+7XsJD7PtEy8ffIraIGHQeyKYDx Um+QD3SrsTaHGhvXs9LRdmT8ptfkVdfl1UdKQ5ZZy+5xS03FGyu5ScetqjIuvkR58D1p IJxMZmpeBfY2SklEHQgb60C7XZU8uQJReDoc11+5KbxhHuoQR4IL4rA1/ugjRPZJiccL ezycEDW6ztnboBg6xomEPML/HCBsDX4TD54jy6131pcYKVJuZSGAPsUifsJgDEiLgwyD 8z3MnoaqoPv2iSkG1ZyBLsNuWQ2tUUd1QQNNe9P8gPtfSum275OwZoV0KEz/RMocYVKH fAZA== X-Gm-Message-State: AOAM532/C9tCYdK/vDzW93ED9Zbh+h53bHEwNq7+9i5gKWxPwrJil47g spzio/mmshIB2b4SDfgWLyxllT3oliMtJ1+fzvs0+JHt X-Google-Smtp-Source: ABdhPJwSK0oW6GQDVlUqBmcJJcMsPvnCYbuT/7DEydBQpl73UZHju2ZhcVyexOOCFuXwNKF9/u2BnbBsYvc/va/W06M= X-Received: by 2002:a05:6402:518d:: with SMTP id q13mr34909966edd.313.1617122082598; Tue, 30 Mar 2021 09:34:42 -0700 (PDT) MIME-Version: 1.0 References: <20210329193828.179993-1-shy828301@gmail.com> <624d1172-cdf9-ce82-aa0b-6646f3bee757@nvidia.com> In-Reply-To: <624d1172-cdf9-ce82-aa0b-6646f3bee757@nvidia.com> From: Yang Shi Date: Tue, 30 Mar 2021 09:34:30 -0700 Message-ID: Subject: Re: [PATCH] mm: gup: remove FOLL_SPLIT To: John Hubbard Cc: Andrew Morton , Linux MM , Linux Kernel Mailing List Content-Type: text/plain; charset="UTF-8" X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: EC14320007C7 X-Stat-Signature: zwpt5z7kxnoh8swztd5khhj43iytzb45 Received-SPF: none (gmail.com>: No applicable sender policy available) receiver=imf11; identity=mailfrom; envelope-from=""; helo=mail-ed1-f50.google.com; client-ip=209.85.208.50 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1617122523-38054 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 Tue, Mar 30, 2021 at 12:08 AM John Hubbard wrote: > > On 3/29/21 12:38 PM, Yang Shi wrote: > > Since commit 5a52c9df62b4 ("uprobe: use FOLL_SPLIT_PMD instead of FOLL_SPLIT") > > and commit ba925fa35057 ("s390/gmap: improve THP splitting") FOLL_SPLIT > > has not been used anymore. Remove the dead code. > > > > Signed-off-by: Yang Shi > > --- > > include/linux/mm.h | 1 - > > mm/gup.c | 28 ++-------------------------- > > 2 files changed, 2 insertions(+), 27 deletions(-) > > > > Looks nice. > > As long as I'm running git grep here, there is one more search hit that should also > be fixed up, as part of a "remove FOLL_SPLIT" patch: > > git grep -nw FOLL_SPLIT > Documentation/vm/transhuge.rst:57:follow_page, the FOLL_SPLIT bit can be specified as a parameter to > > Reviewed-by: John Hubbard Thanks. Removed the reference to FOLL_SPLIT in documentation for v2. > > thanks, > -- > John Hubbard > NVIDIA > > > diff --git a/include/linux/mm.h b/include/linux/mm.h > > index 8ba434287387..3568836841f9 100644 > > --- a/include/linux/mm.h > > +++ b/include/linux/mm.h > > @@ -2780,7 +2780,6 @@ struct page *follow_page(struct vm_area_struct *vma, unsigned long address, > > #define FOLL_NOWAIT 0x20 /* if a disk transfer is needed, start the IO > > * and return without waiting upon it */ > > #define FOLL_POPULATE 0x40 /* fault in page */ > > -#define FOLL_SPLIT 0x80 /* don't return transhuge pages, split them */ > > #define FOLL_HWPOISON 0x100 /* check page is hwpoisoned */ > > #define FOLL_NUMA 0x200 /* force NUMA hinting page fault */ > > #define FOLL_MIGRATION 0x400 /* wait for page to replace migration entry */ > > diff --git a/mm/gup.c b/mm/gup.c > > index e40579624f10..f3d45a8f18ae 100644 > > --- a/mm/gup.c > > +++ b/mm/gup.c > > @@ -435,18 +435,6 @@ static struct page *follow_page_pte(struct vm_area_struct *vma, > > } > > } > > > > - if (flags & FOLL_SPLIT && PageTransCompound(page)) { > > - get_page(page); > > - pte_unmap_unlock(ptep, ptl); > > - lock_page(page); > > - ret = split_huge_page(page); > > - unlock_page(page); > > - put_page(page); > > - if (ret) > > - return ERR_PTR(ret); > > - goto retry; > > - } > > - > > /* try_grab_page() does nothing unless FOLL_GET or FOLL_PIN is set. */ > > if (unlikely(!try_grab_page(page, flags))) { > > page = ERR_PTR(-ENOMEM); > > @@ -591,7 +579,7 @@ static struct page *follow_pmd_mask(struct vm_area_struct *vma, > > spin_unlock(ptl); > > return follow_page_pte(vma, address, pmd, flags, &ctx->pgmap); > > } > > - if (flags & (FOLL_SPLIT | FOLL_SPLIT_PMD)) { > > + if (flags & FOLL_SPLIT_PMD) { > > int ret; > > page = pmd_page(*pmd); > > if (is_huge_zero_page(page)) { > > @@ -600,19 +588,7 @@ static struct page *follow_pmd_mask(struct vm_area_struct *vma, > > split_huge_pmd(vma, pmd, address); > > if (pmd_trans_unstable(pmd)) > > ret = -EBUSY; > > - } else if (flags & FOLL_SPLIT) { > > - if (unlikely(!try_get_page(page))) { > > - spin_unlock(ptl); > > - return ERR_PTR(-ENOMEM); > > - } > > - spin_unlock(ptl); > > - lock_page(page); > > - ret = split_huge_page(page); > > - unlock_page(page); > > - put_page(page); > > - if (pmd_none(*pmd)) > > - return no_page_table(vma, flags); > > - } else { /* flags & FOLL_SPLIT_PMD */ > > + } else { > > spin_unlock(ptl); > > split_huge_pmd(vma, pmd, address); > > ret = pte_alloc(mm, pmd) ? -ENOMEM : 0; > > >