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=-16.1 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED 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 CCCA5C433DB for ; Fri, 26 Feb 2021 20:38:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6C9D464F03 for ; Fri, 26 Feb 2021 20:38:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230131AbhBZUiE (ORCPT ); Fri, 26 Feb 2021 15:38:04 -0500 Received: from mail.kernel.org ([198.145.29.99]:50764 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230477AbhBZUh6 (ORCPT ); Fri, 26 Feb 2021 15:37:58 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 5521E64F03; Fri, 26 Feb 2021 20:37:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1614371837; bh=Ly0f27B7LvWPQIY/noxzHUfAiBR7+fZJjZHCqygyerw=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=zJhisgXnLiT9g94dR6TY00koT/Ql+rflRrpcB41mBSqMhYtj/D6Yx166tD0LQTGmp qlINLn7lfkO6b+9EncYHBQ+FTqGI6/MOMpYyC76WwLDirIBX32wST/4Dz+JkrSKAHo WmM/b4uUHPf7DrEkKbDAoqnnT6lrzQZEjJ7aCOPI= Date: Fri, 26 Feb 2021 12:37:16 -0800 From: Andrew Morton To: Palmer Dabbelt Cc: atishp@atishpatra.org, peterz@infradead.org, srikar@linux.vnet.ibm.com, valentin.schneider@arm.com, vbabka@suse.cz, mpe@ellerman.id.au, Palmer Dabbelt , linux-kernel@vger.kernel.org, linux-mm@kvack.org, kernel-team@android.com, "Kirill A. Shutemov" Subject: Re: [PATCH 1/2] mm: Guard a use of node_reclaim_distance with CONFIFG_NUMA Message-Id: <20210226123716.6bc2a463e0ee9d1770c7966b@linux-foundation.org> In-Reply-To: <20210226201721.510177-1-palmer@dabbelt.com> References: <20210226201721.510177-1-palmer@dabbelt.com> X-Mailer: Sylpheed 3.5.1 (GTK+ 2.24.31; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 26 Feb 2021 12:17:20 -0800 Palmer Dabbelt wrote: > From: Palmer Dabbelt > > This is only useful under CONFIG_NUMA. IIUC skipping the check is the > right thing to do here, as without CONFIG_NUMA there will never be any > large node distances on non-NUMA systems. > > I expected this to manifest as a link failure under (!CONFIG_NUMA && > CONFIG_TRANSPARENT_HUGE_PAGES), but I'm not actually seeing that. I > think the reference is just getting pruned before it's checked, but I > didn't get that from reading the code so I'm worried I'm missing > something. > > Either way, this is necessary to guard the definition of > node_reclaim_distance with CONFIG_NUMA. > > Signed-off-by: Palmer Dabbelt > --- > mm/khugepaged.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/mm/khugepaged.c b/mm/khugepaged.c > index a7d6cb912b05..b1bf191c3a54 100644 > --- a/mm/khugepaged.c > +++ b/mm/khugepaged.c > @@ -819,8 +819,10 @@ static bool khugepaged_scan_abort(int nid) > for (i = 0; i < MAX_NUMNODES; i++) { > if (!khugepaged_node_load[i]) > continue; > +#ifdef CONFIG_NUMA > if (node_distance(nid, i) > node_reclaim_distance) > return true; > +#endif > } > return false; > } This makes the entire loop a no-op. Perhaps Kirill can help take a look at removing unnecessary code in khugepaged.c when CONFIG_NUMA=n?