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_CR_TRAILER, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 07EEBC433E9 for ; Thu, 18 Mar 2021 11:38:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B9C5A64EED for ; Thu, 18 Mar 2021 11:38:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229987AbhCRLiT (ORCPT ); Thu, 18 Mar 2021 07:38:19 -0400 Received: from mx2.suse.de ([195.135.220.15]:45646 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230160AbhCRLiD (ORCPT ); Thu, 18 Mar 2021 07:38:03 -0400 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=1616067482; 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=5en59u2vhZFX9B//yzzeVhhgJpV6/PW65MgkV2h14ek=; b=t4zk6oPAgCfU9r48PlULtgbLpV0TdPucVWM4kwM5Yt7TGi1GFxiSgTklp2BU7u/5Wb1S1k 5TxgV9gKvRS8Dhk1lbx1Syh9Ng1oNSA9yXzRFpxVAjdx0S/Jc+QV9YAdLWH8lcPj7Olpm2 S33IKdc8eXKGeTw6WXrbotHPSUr0QOc= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 5B49AACBF; Thu, 18 Mar 2021 11:38:02 +0000 (UTC) Date: Thu, 18 Mar 2021 12:37:44 +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 1/5] mm,page_alloc: Bail out earlier on -ENOMEM in alloc_contig_migrate_range Message-ID: References: <20210317111251.17808-1-osalvador@suse.de> <20210317111251.17808-2-osalvador@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu 18-03-21 12:04:00, Oscar Salvador wrote: > On Wed, Mar 17, 2021 at 03:05:40PM +0100, Michal Hocko wrote: > > That being said, bailing out early makes sense to me. But now that > > you've made me look into the migrate_pages excellent error state reporting > > I suspect we have a bug here. Note the > > "Returns the number of pages that were not migrated, or an error code." > > > > but I do not see putback_movable_pages for ret > 0 so it seems we might > > leak some pages. > > I fell for the same thing when looking at that code. > It took a while until I realized what was really going on. > > > > Signed-off-by: Oscar Salvador > > > Acked-by: Vlastimil Babka > > > Reviewed-by: David Hildenbrand > > > > The patch itself looks reasonable but make sure to mention this is mere > > cosmetic change unless there is a real problem fixed by this. > > Acked-by: Michal Hocko > > What about appending the following in the changelog: > > "Note that this is not fixing a real issue, just a cosmetic change. Although > we can save some cycles by backing off ealier." Sounds good to me. -- Michal Hocko SUSE Labs