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 5C779C433F5 for ; Tue, 10 May 2022 18:59:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1345854AbiEJS72 (ORCPT ); Tue, 10 May 2022 14:59:28 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46818 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232821AbiEJS7Z (ORCPT ); Tue, 10 May 2022 14:59:25 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 77AFA54BE5 for ; Tue, 10 May 2022 11:59:24 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 15ED161117 for ; Tue, 10 May 2022 18:59:24 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2103CC385C2; Tue, 10 May 2022 18:59:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1652209163; bh=ajpLuMXrPrNofjFAsynlZdqAggkQqVZljm1Ud2j7xMI=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=Wwx1rD46KZaErYa7By9rx5yDPlei1DEANzUTbLv1OZyvear0dGSPX2BAUnJPlCwVe +xXi7JGGDUHdv06EPlpIskQ/VHDKMCTDa7WvE+kqk2Le6Pp6G28tqJlxb66xGccjlo BYyk0KWR9PjjeooUxIKADMnzYh6Ws0PTkX0XFp6c= Date: Tue, 10 May 2022 11:59:22 -0700 From: Andrew Morton To: Qi Zheng Cc: akinobu.mita@gmail.com, vbabka@suse.cz, gregkh@linuxfoundation.org, jirislaby@kernel.org, rostedt@goodmis.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH 1/2] mm: fix missing handler for __GFP_NOWARN Message-Id: <20220510115922.350a496ca8b91686c1758282@linux-foundation.org> In-Reply-To: <20220510113809.80626-1-zhengqi.arch@bytedance.com> References: <20220510113809.80626-1-zhengqi.arch@bytedance.com> X-Mailer: Sylpheed 3.7.0 (GTK+ 2.24.33; x86_64-redhat-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 Tue, 10 May 2022 19:38:08 +0800 Qi Zheng wrote: > We expect no warnings to be issued when we specify __GFP_NOWARN, but > currently in paths like alloc_pages() and kmalloc(), there are still > some warnings printed, fix it. Looks sane to me. > --- a/mm/internal.h > +++ b/mm/internal.h > @@ -35,6 +35,17 @@ struct folio_batch; > /* Do not use these with a slab allocator */ > #define GFP_SLAB_BUG_MASK (__GFP_DMA32|__GFP_HIGHMEM|~__GFP_BITS_MASK) > > +#define WARN_ON_ONCE_GFP(cond, gfp) ({ \ > + static bool __section(".data.once") __warned; \ > + int __ret_warn_once = !!(cond); \ > + \ > + if (unlikely(!(gfp & __GFP_NOWARN) && __ret_warn_once && !__warned)) { \ > + __warned = true; \ > + WARN_ON(1); \ > + } \ > + unlikely(__ret_warn_once); \ > +}) I don't think WARN_ON_ONCE_GFP is a good name for this. But WARN_ON_ONCE_IF_NOT_GFP_NOWARN is too long :( WARN_ON_ONCE_NOWARN might be better. No strong opinion here, really. > @@ -4902,8 +4906,8 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order, > * We also sanity check to catch abuse of atomic reserves being used by > * callers that are not in atomic context. > */ > - if (WARN_ON_ONCE((gfp_mask & (__GFP_ATOMIC|__GFP_DIRECT_RECLAIM)) == > - (__GFP_ATOMIC|__GFP_DIRECT_RECLAIM))) > + if (WARN_ON_ONCE_GFP((gfp_mask & (__GFP_ATOMIC|__GFP_DIRECT_RECLAIM)) == > + (__GFP_ATOMIC|__GFP_DIRECT_RECLAIM), gfp_mask)) > gfp_mask &= ~__GFP_ATOMIC; > > retry_cpuset: I dropped this hunk - Neil's "mm: discard __GFP_ATOMIC" (https://lkml.kernel.org/r/163712397076.13692.4727608274002939094@noble.neil.brown.name) deleted this code.