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=-10.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 BAADEC433DB for ; Wed, 17 Mar 2021 14:49:47 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 467B964F3E for ; Wed, 17 Mar 2021 14:49:47 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 467B964F3E Authentication-Results: mail.kernel.org; dmarc=fail (p=quarantine dis=none) header.from=suse.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id B3D7F6B007B; Wed, 17 Mar 2021 10:49:46 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id B14456B007E; Wed, 17 Mar 2021 10:49:46 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 9C3C66B007B; Wed, 17 Mar 2021 10:49:46 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0173.hostedemail.com [216.40.44.173]) by kanga.kvack.org (Postfix) with ESMTP id 82D326B007B for ; Wed, 17 Mar 2021 10:49:46 -0400 (EDT) Received: from smtpin14.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id 209F2824999B for ; Wed, 17 Mar 2021 14:49:46 +0000 (UTC) X-FDA: 77929650372.14.91219BE Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) by imf25.hostedemail.com (Postfix) with ESMTP id F270860258CE for ; Wed, 17 Mar 2021 14:12:32 +0000 (UTC) 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=1615990350; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=aAUcDe4pvPLn4fC/tremYQrLTY4DcLiLDV9Wbabr0yI=; b=qNXoN1DKzjDs4kcMcCP/zoOlx/Kirf7ZUCuEqfN4VYQZULteWQVKHEH2MhKdOSTNaW1oVI mDPKxwGzmFNTsRmdmY4LwnIT06xCAookjzKr0fgdOWF+YD0gTjuKarNw39oe0+T5wCyoNS MUGbIBtvsjgWCb18AeOV7UmI2TZ94dU= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 20616AC47; Wed, 17 Mar 2021 14:12:30 +0000 (UTC) Date: Wed, 17 Mar 2021 15:12:29 +0100 From: Michal Hocko To: Oscar Salvador Cc: Andrew Morton , Vlastimil Babka , David Hildenbrand , Muchun Song , Mike Kravetz , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v5 2/5] mm,compaction: Let isolate_migratepages_{range,block} return error codes Message-ID: References: <20210317111251.17808-1-osalvador@suse.de> <20210317111251.17808-3-osalvador@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210317111251.17808-3-osalvador@suse.de> X-Stat-Signature: sfu9k66gypz1bezne1aqzqbsitjicchk X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: F270860258CE Received-SPF: none (suse.com>: No applicable sender policy available) receiver=imf25; identity=mailfrom; envelope-from=""; helo=mx2.suse.de; client-ip=195.135.220.15 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1615990352-956615 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 Wed 17-03-21 12:12:48, Oscar Salvador wrote: > Currently, isolate_migratepages_{range,block} and their callers use > a pfn == 0 vs pfn != 0 scheme to let the caller know whether there was > any error during isolation. > This does not work as soon as we need to start reporting different error > codes and make sure we pass them down the chain, so they are properly > interpreted by functions like e.g: alloc_contig_range. > > Let us rework isolate_migratepages_{range,block} so we can report error > codes. Yes this is an improvement. > Since isolate_migratepages_block will stop returning the next pfn to be > scanned, we reuse the cc->migrate_pfn field to keep track of that. This looks hakish and I cannot really tell that users of cc->migrate_pfn work as intended. > @@ -810,6 +811,8 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn, > unsigned long next_skip_pfn = 0; > bool skip_updated = false; > > + cc->migrate_pfn = low_pfn; > + > /* > * Ensure that there are not too many pages isolated from the LRU > * list by either parallel reclaimers or compaction. If there are, > @@ -818,16 +821,16 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn, > while (unlikely(too_many_isolated(pgdat))) { > /* stop isolation if there are still pages not migrated */ > if (cc->nr_migratepages) > - return 0; > + return -EINTR; > > /* async migration should just abort */ > if (cc->mode == MIGRATE_ASYNC) > - return 0; > + return -EINTR; EINTR for anything other than signal based bail out is really confusing. -- Michal Hocko SUSE Labs