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=-12.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=ham 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 2C201C433B4 for ; Wed, 7 Apr 2021 09:31:31 +0000 (UTC) Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id C38BA61139 for ; Wed, 7 Apr 2021 09:31:30 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C38BA61139 Authentication-Results: mail.kernel.org; dmarc=fail (p=quarantine dis=none) header.from=suse.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=xen-devel-bounces@lists.xenproject.org Received: from list by lists.xenproject.org with outflank-mailman.106553.203769 (Exim 4.92) (envelope-from ) id 1lU4Wt-0005GS-2R; Wed, 07 Apr 2021 09:31:19 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 106553.203769; Wed, 07 Apr 2021 09:31:19 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1lU4Ws-0005GL-Vf; Wed, 07 Apr 2021 09:31:18 +0000 Received: by outflank-mailman (input) for mailman id 106553; Wed, 07 Apr 2021 09:31:17 +0000 Received: from all-amaz-eas1.inumbo.com ([34.197.232.57] helo=us1-amaz-eas2.inumbo.com) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1lU4Wr-0005GG-Oo for xen-devel@lists.xenproject.org; Wed, 07 Apr 2021 09:31:17 +0000 Received: from mx2.suse.de (unknown [195.135.220.15]) by us1-amaz-eas2.inumbo.com (Halon) with ESMTPS id dcdd9b0b-2cac-4fb0-b250-1bde47ce1df9; Wed, 07 Apr 2021 09:31:16 +0000 (UTC) Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 038C5B06A; Wed, 7 Apr 2021 09:31:16 +0000 (UTC) X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" X-Inumbo-ID: dcdd9b0b-2cac-4fb0-b250-1bde47ce1df9 X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1617787876; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=l/ThV8W3CSBtQEZA9sD7HLLVdJCK7g+cTmPh3/5rDcI=; b=V8eScDm0JCr67RLjpgxTjKQFAcr0PNE3FQiQbcisET4Vze2CRm8O+BAe9O2xWWKvdrx1kB QQrFtyQlAOpNnPitT5CWOnYFT/DtRaveWFKUuG01qsHfcqeTYZ5ClvMrnS9P1D4ehDE46c lu21A8NgKMwYW1csLF0Jm+uLKFj3j7g= Subject: Re: [PATCH] xen/page_alloc: Don't hold the heap_lock when clearing PGC_need_scrub To: Julien Grall Cc: Julien Grall , Andrew Cooper , George Dunlap , Ian Jackson , Stefano Stabellini , Wei Liu , xen-devel@lists.xenproject.org References: <20210406193032.16976-1-julien@xen.org> From: Jan Beulich Message-ID: <35e0d1df-7aac-4205-4545-3218601bae4e@suse.com> Date: Wed, 7 Apr 2021 11:31:16 +0200 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.9.0 MIME-Version: 1.0 In-Reply-To: <20210406193032.16976-1-julien@xen.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit On 06.04.2021 21:30, Julien Grall wrote: > From: Julien Grall > > Currently, the heap_lock is held when clearing PGC_need_scrub in > alloc_heap_pages(). However, this is unnecessary because the only caller > (mark_page_offline()) that can concurrently modify the count_info is > using cmpxchg() in a loop. > > Therefore, rework the code to avoid holding the heap_lock and use > test_and_clear_bit() instead. > > Signed-off-by: Julien Grall Reviewed-by: Jan Beulich