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=-3.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,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 F2C66C47082 for ; Tue, 8 Jun 2021 12:33:09 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id AE10A6135A for ; Tue, 8 Jun 2021 12:33:09 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org AE10A6135A Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 0E3456B006C; Tue, 8 Jun 2021 08:33:09 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 093C96B006E; Tue, 8 Jun 2021 08:33:09 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id E76296B0070; Tue, 8 Jun 2021 08:33:08 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0141.hostedemail.com [216.40.44.141]) by kanga.kvack.org (Postfix) with ESMTP id B5AA96B006C for ; Tue, 8 Jun 2021 08:33:08 -0400 (EDT) Received: from smtpin22.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 53EEAA751 for ; Tue, 8 Jun 2021 12:33:08 +0000 (UTC) X-FDA: 78230496456.22.5EB88D4 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) by imf12.hostedemail.com (Postfix) with ESMTP id BB32037C for ; Tue, 8 Jun 2021 12:33:02 +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=YSGQEI1WX6YiXANPfcZHnOB1Uu7nxLS3hbjqa7fmpSI=; b=NqHKRKUraLAIML21HZSAmknZ4F VU5XAZc1pxC1JYcy9gVMgNVLmzW0kR8IhWQOQCr2WAc8FpmKcoi/Lv+Sj0J3I61+d5r3FQXyk2gar I/HUhvhoeZr/WgTYH6NnOvkdF8J4uCni+tx1Z0TXe+I36WvE/Yjt0M8y7C7lwOOwOi3OYL3TiHGm5 KSomQovXbqyDh8p9A3jwiJkkNpowT3Xae/S61GX7UFaTq23bBlPF/1GxUz/xxODH2dqV2AiC+SAx8 +KpXfOtPcWdWemeJ0sglnemOGsPokjv2ywQSdycZUwXg/bq4LK6QqJLG9eXh8cBdU//QVm4mFRJkH z19eDUYw==; Received: from willy by casper.infradead.org with local (Exim 4.94 #2 (Red Hat Linux)) id 1lqau6-00Gw37-10; Tue, 08 Jun 2021 12:32:33 +0000 Date: Tue, 8 Jun 2021 13:32:21 +0100 From: Matthew Wilcox To: "Kirill A. Shutemov" Cc: Xu Yu , linux-mm@kvack.org, linux-kernel@vger.kernel.org, hughd@google.com, akpm@linux-foundation.org, gavin.dg@linux.alibaba.com Subject: Re: [PATCH v2] mm, thp: use head page in __migration_entry_wait Message-ID: References: <20210608120026.ugfh72ydjeba44bo@box.shutemov.name> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210608120026.ugfh72ydjeba44bo@box.shutemov.name> Authentication-Results: imf12.hostedemail.com; dkim=pass header.d=infradead.org header.s=casper.20170209 header.b=NqHKRKUr; dmarc=none; spf=none (imf12.hostedemail.com: domain of willy@infradead.org has no SPF policy when checking 90.155.50.34) smtp.mailfrom=willy@infradead.org X-Rspamd-Server: rspam02 X-Stat-Signature: equptntwd8cburjxgekc7jtm6feyedat X-Rspamd-Queue-Id: BB32037C X-HE-Tag: 1623155582-709102 X-Bogosity: Ham, tests=bogofilter, spamicity=0.033491, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Tue, Jun 08, 2021 at 03:00:26PM +0300, Kirill A. Shutemov wrote: > But there's one quirk: if split succeed we effectively wait on wrong > page to be unlocked. And it may take indefinite time if split_huge_page() > was called on the head page. Hardly indefinite time ... callers of split_huge_page_to_list() usually unlock the page soon after. Actually, I can't find one that doesn't call unlock_page() within a few lines of calling split_huge_page_to_list().