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=-0.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,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 98214C28CBC for ; Wed, 6 May 2020 18:32:36 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 57EFD206D5 for ; Wed, 6 May 2020 18:32:36 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="rJLEiPN7" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 57EFD206D5 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 DC2EC8E0005; Wed, 6 May 2020 14:32:35 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id D73148E0003; Wed, 6 May 2020 14:32:35 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id C884F8E0005; Wed, 6 May 2020 14:32:35 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id AEF508E0003 for ; Wed, 6 May 2020 14:32:35 -0400 (EDT) Received: from smtpin22.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 71155A2B9 for ; Wed, 6 May 2020 18:32:35 +0000 (UTC) X-FDA: 76787139870.22.wind52_8afad89fdb200 X-HE-Tag: wind52_8afad89fdb200 X-Filterd-Recvd-Size: 3785 Received: from mail-ed1-f65.google.com (mail-ed1-f65.google.com [209.85.208.65]) by imf16.hostedemail.com (Postfix) with ESMTP for ; Wed, 6 May 2020 18:32:34 +0000 (UTC) Received: by mail-ed1-f65.google.com with SMTP id d16so2876091edq.7 for ; Wed, 06 May 2020 11:32:34 -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=Fq3C3PbiEHBNQ27byMZOeuqdKYIZw/ni/msqiBB7jyw=; b=rJLEiPN7+PxVlf0QK9PQNUT6kdIjMim7/Ob4MOBhcoNSlOu2jcUZTT6HZnRkZBplSw gZ7/yA0PANlt5Anpszzp4vP722DW0sXC9Gm78C9nyFl2PR2ny6S4LFG+8XYxupDtF+M7 svQk0iI11QWz45fTvs5s2+YBLElpfugmc/46+FDIU5YtMEcbsh0Er/PXglJhernwl7Sq 5JiIoVLofL284wjgrRU7sH68j4j+ZtIrlo8hPqZf3iQPaACAasJnBrboSvJDeNuQoWKi LrRNEPC/B9g1dqRX1W/SNp+CcAAboD7hzPJ08Ioz+pqzHU0laa/KsjTEOXl5mNNPghME G5Aw== 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=Fq3C3PbiEHBNQ27byMZOeuqdKYIZw/ni/msqiBB7jyw=; b=O8dk8G+dbKwRZmHMHXjogpDgdC+cZvmavNyWQxdLMP8L+cMyO5zSFRpvpV13ygihbR wK5jI0XtQb8ODOjGiJayNI4e9Pze1Cz8iJDvhvZ273OAv2kh4Ukh9xcM4JrJ4f4Byr3A 5H5OfmKLqLWC4Xwgngi6asWT4jLceNss0c4L1iXp1qRVrWiihC6Q62H+QCCjIe24jvbh rslHfujUqDOPALGWdKbp4r3BbVo158yk3ZIVtd8tkHKA4E6eJLz53Q1OT9aRKPNulGQZ 1iZna4p7SYzprZDpm7xXsJM14zHQQdSjGiAg+80Ug+cC48pQF6Wiuzgr3XR8rCtqg+bt 1dFQ== X-Gm-Message-State: AGi0PuYpSVkJak+9fZLcdwHkl9tFDBeUoIj3neueoHUUjEEqSv3zw1nx JWtKpmWoAnMqtO7zh6a70k978q1iNNO5AlnpoZwIWqGP X-Google-Smtp-Source: APiQypIqKVPkPU9lpEJGXc3tDKlNRebjzrlGVMGBlrUrwK8oBbdsyu+LRyPffWUSAmpIOciZmJuZppyjOo2b3eZ4pfE= X-Received: by 2002:a05:6402:558:: with SMTP id i24mr7963797edx.347.1588789953782; Wed, 06 May 2020 11:32:33 -0700 (PDT) MIME-Version: 1.0 References: <20200429133657.22632-1-willy@infradead.org> <20200429133657.22632-19-willy@infradead.org> <20200504031036.GB16070@bombadil.infradead.org> In-Reply-To: <20200504031036.GB16070@bombadil.infradead.org> From: Yang Shi Date: Wed, 6 May 2020 11:32:10 -0700 Message-ID: Subject: Re: [PATCH v3 18/25] mm: Allow large pages to be added to the page cache To: Matthew Wilcox Cc: Linux FS-devel Mailing List , Linux MM , Linux Kernel Mailing List Content-Type: text/plain; charset="UTF-8" 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, May 3, 2020 at 8:10 PM Matthew Wilcox wrote: > > On Wed, Apr 29, 2020 at 06:36:50AM -0700, Matthew Wilcox wrote: > > @@ -886,7 +906,7 @@ static int __add_to_page_cache_locked(struct page *page, > > /* Leave page->index set: truncation relies upon it */ > > if (!huge) > > mem_cgroup_cancel_charge(page, memcg, false); > > - put_page(page); > > + page_ref_sub(page, nr); > > return xas_error(&xas); > > } > > ALLOW_ERROR_INJECTION(__add_to_page_cache_locked, ERRNO); > > This is wrong. page_ref_sub() will not call __put_page() if the refcount > gets to zero. What do people prefer? > > - put_page(page); > > (a) > + put_thp(page); > > (b) > + put_page_nr(page, nr); > > (c) > + if (page_ref_sub_return(page, nr) == 0) > + __put_page(page); b or c IMHO. The shmem uses page_ref_add/page_ref_sub so we'd better follow it. If go with b, it sounds better to add get_page_nr() as well. >