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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 50757C4332F for ; Mon, 7 Nov 2022 07:55:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231524AbiKGHz6 (ORCPT ); Mon, 7 Nov 2022 02:55:58 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54662 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231327AbiKGHzz (ORCPT ); Mon, 7 Nov 2022 02:55:55 -0500 Received: from smtp-out1.suse.de (smtp-out1.suse.de [195.135.220.28]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 320FC13EA0 for ; Sun, 6 Nov 2022 23:55:54 -0800 (PST) Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out1.suse.de (Postfix) with ESMTPS id DDD902265A; Mon, 7 Nov 2022 07:55:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1667807752; 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=rmFwxdFZoUVOelw7Ug/+kLQijnei7KhnrMrS2/YuBjU=; b=J4Utqd/cydbaUS5SBk5GJw6KgoAhiBsjaBqNSJPJr9EbaFXt+Z04hmY37VjtdcLA66wGEH NzVaeFugAL+NAjZNb87+tG0MyoJbE4JbDuFNkyJe1KhgIkKjc4Z16hWJVJ02M+iXsvntn9 AoV1Ux+Ichw5Ojpk09sCsdeHdfYfwC8= Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id BF64C13AC7; Mon, 7 Nov 2022 07:55:52 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id ESKKLAi6aGNgFwAAMHmgww (envelope-from ); Mon, 07 Nov 2022 07:55:52 +0000 Date: Mon, 7 Nov 2022 08:55:51 +0100 From: Michal Hocko To: Yang Shi Cc: zokeefe@google.com, akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [v2 PATCH 2/2] mm: don't warn if the node is offlined Message-ID: References: <20221103213641.7296-1-shy828301@gmail.com> <20221103213641.7296-2-shy828301@gmail.com> 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 Fri 04-11-22 13:52:52, Yang Shi wrote: > On Fri, Nov 4, 2022 at 12:51 PM Michal Hocko wrote: > > > > On Fri 04-11-22 10:42:45, Yang Shi wrote: > > > On Fri, Nov 4, 2022 at 2:56 AM Michal Hocko wrote: > > > > > > > > On Fri 04-11-22 10:35:21, Michal Hocko wrote: > > > > [...] > > > > > diff --git a/include/linux/gfp.h b/include/linux/gfp.h > > > > > index ef4aea3b356e..308daafc4871 100644 > > > > > --- a/include/linux/gfp.h > > > > > +++ b/include/linux/gfp.h > > > > > @@ -227,7 +227,10 @@ static inline > > > > > struct folio *__folio_alloc_node(gfp_t gfp, unsigned int order, int nid) > > > > > { > > > > > VM_BUG_ON(nid < 0 || nid >= MAX_NUMNODES); > > > > > - VM_WARN_ON((gfp & __GFP_THISNODE) && !node_online(nid)); > > > > > + if((gfp & __GFP_THISNODE) && !node_online(nid)) { > > > > > > > > or maybe even better > > > > if ((gfp & (__GFP_THISNODE|__GFP_NOWARN) == __GFP_THISNODE|__GFP_NOWARN) && !node_online(nid)) > > > > > > > > because it doesn't really make much sense to dump this information if > > > > the allocation failure is going to provide sufficient (and even more > > > > comprehensive) context for the failure. It looks more hairy but this can > > > > be hidden in a nice little helper shared between the two callers. > > > > > > Thanks a lot for the suggestion, printing warning if the gfp flag > > > allows sounds like a good idea to me. Will adopt it. But the check > > > should look like: > > > > > > if ((gfp & __GFP_THISNODE) && !(gfp & __GFP_NOWARN) && !node_online(nid)) > > > > The idea was to warn if __GFP_NOWARN _was_ specified. Otherwise we will > > get an allocation failure splat from the page allocator and there it > > will be clear that the node doesn't have any memory associated. It is > > exactly __GFP_NOWARN case that would be a silent failure and potentially > > a buggy code (like this THP collapse path). See my point? > > Aha, yeah, see your point now. I didn't see the splat from the > allocator from the bug report, then I realized it had not called into > allocator yet before the warning was triggered. And it would trigger even if it did because GFP_TRANSHUGE has __GFP_NOWARN -- Michal Hocko SUSE Labs