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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 95F28C433F5 for ; Tue, 28 Sep 2021 12:07:42 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id A981F60F6E for ; Tue, 28 Sep 2021 12:07:41 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org A981F60F6E Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvack.org Received: by kanga.kvack.org (Postfix) id 20A6E900003; Tue, 28 Sep 2021 08:07:41 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 1B985900002; Tue, 28 Sep 2021 08:07:41 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 0A8F2900003; Tue, 28 Sep 2021 08:07:41 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0174.hostedemail.com [216.40.44.174]) by kanga.kvack.org (Postfix) with ESMTP id EE396900002 for ; Tue, 28 Sep 2021 08:07:40 -0400 (EDT) Received: from smtpin27.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id AD2B5181316C5 for ; Tue, 28 Sep 2021 12:07:40 +0000 (UTC) X-FDA: 78636857880.27.86FF850 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) by imf22.hostedemail.com (Postfix) with ESMTP id 6942E1906 for ; Tue, 28 Sep 2021 12:07:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=c23zswK9ANwThDRQl4nW53akkUWxcJ1VY9cYgeLMJuw=; b=bTsJeJrdv5GIjRUbslEdSR12rC 7eZuYxrSkAlpwYk/qHgsIGaJQmdLr+OlBlMcCE4e7SCgQZxikwXe6W4zoAZStkHpKM3/RSQZ6L6OE pCNZXIUKGDYT7+OJZVn/O3NMMuwDzniYm4V03s0FL7wbL2CDWzR8sD6w4lihtglY3zq88zNlM2p+z 2hsWInqC5s0zAk9USyp/Z6eGK7siTWGSyf/fBqHA8+fnOxGYISJ/ox7NZZuj2SCw5xZT0GSWAKqT9 BeCYN6ESPQtWcbRXAbVDc5TM/U5LeVyaB8xEYuCNdbnN81Fnf7svvPa3MsrDycFtMkTbtgkqgo+PD zXDe340w==; Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1mVBsd-00ApTi-Go; Tue, 28 Sep 2021 12:06:58 +0000 Date: Tue, 28 Sep 2021 13:06:39 +0100 From: Matthew Wilcox To: Song Liu Cc: Rongwei Wang , Andrew Morton , Linux MM , Linux Kernel Mailing List , William Kucharski , Hugh Dickins Subject: Re: [PATCH v2 1/2] mm, thp: check page mapping when truncating page cache Message-ID: References: <20210906121200.57905-1-rongwei.wang@linux.alibaba.com> <20210922070645.47345-2-rongwei.wang@linux.alibaba.com> <20210923194343.ca0f29e1c4d361170343a6f2@linux-foundation.org> <9e41661d-9919-d556-8c49-610dae157553@linux.alibaba.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 6942E1906 X-Stat-Signature: 6ibp9uaparkb1sd3etezeismebadciay Authentication-Results: imf22.hostedemail.com; dkim=pass header.d=infradead.org header.s=casper.20170209 header.b=bTsJeJrd; dmarc=none; spf=none (imf22.hostedemail.com: domain of willy@infradead.org has no SPF policy when checking 90.155.50.34) smtp.mailfrom=willy@infradead.org X-HE-Tag: 1632830859-542063 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, Sep 27, 2021 at 03:24:47PM -0700, Song Liu wrote: > OTOH, does it make sense to block writes within khugepaged, like: > @@ -1652,6 +1653,11 @@ static void collapse_file(struct mm_struct *mm, > /* Only allocate from the target node */ > gfp = alloc_hugepage_khugepaged_gfpmask() | __GFP_THISNODE; > > + if (deny_write_access(file)) { > + result = SCAN_BUSY_WRITE; > + return; > + } The problem is that it denies, rather than blocking. That means that the writer gets ETXTBSY instead of waiting until khugepaged is done.