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 81A85C433EF for ; Wed, 12 Jan 2022 10:29:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239498AbiALK3D (ORCPT ); Wed, 12 Jan 2022 05:29:03 -0500 Received: from smtp-out2.suse.de ([195.135.220.29]:35690 "EHLO smtp-out2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239391AbiALK3A (ORCPT ); Wed, 12 Jan 2022 05:29:00 -0500 Received: from relay2.suse.de (relay2.suse.de [149.44.160.134]) by smtp-out2.suse.de (Postfix) with ESMTP id EE1A51F3CA; Wed, 12 Jan 2022 10:28:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1641983338; 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=ioyVnpN3K6fNhs+IEe7aVsyN+KrufIvhdGNWWrmI3JA=; b=qA94ONzIs4uB2pR3BTbt8lg3/96/Y38YAMcV7cOYTaUW8EuHvMn5oJsISzeqOjc26MBK/0 H92wU1dghL/np4cg9lwZeon9d2awSYlsbKrolCzdJObL0Zw8ywEXHX4w6vT+gkQ5QjI/H1 cNQn+crVBa9yWVlPheo9PWGsEYHgcz8= Received: from suse.cz (unknown [10.100.201.86]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by relay2.suse.de (Postfix) with ESMTPS id 3E91FA3B83; Wed, 12 Jan 2022 10:28:58 +0000 (UTC) Date: Wed, 12 Jan 2022 11:28:57 +0100 From: Michal Hocko To: Yu Zhao Cc: Andrew Morton , Linus Torvalds , Andi Kleen , Catalin Marinas , Dave Hansen , Hillf Danton , Jens Axboe , Jesse Barnes , Johannes Weiner , Jonathan Corbet , Matthew Wilcox , Mel Gorman , Michael Larabel , Rik van Riel , Vlastimil Babka , Will Deacon , Ying Huang , linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, page-reclaim@google.com, x86@kernel.org, Konstantin Kharlamov Subject: Re: [PATCH v6 6/9] mm: multigenerational lru: aging Message-ID: References: <20220104202227.2903605-1-yuzhao@google.com> <20220104202227.2903605-7-yuzhao@google.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-doc@vger.kernel.org On Tue 11-01-22 16:16:57, Yu Zhao wrote: > On Mon, Jan 10, 2022 at 04:01:13PM +0100, Michal Hocko wrote: > > On Thu 06-01-22 17:12:18, Michal Hocko wrote: > > > On Tue 04-01-22 13:22:25, Yu Zhao wrote: > > > > +static struct lru_gen_mm_walk *alloc_mm_walk(void) > > > > +{ > > > > + if (!current->reclaim_state || !current->reclaim_state->mm_walk) > > > > + return kvzalloc(sizeof(struct lru_gen_mm_walk), GFP_KERNEL); > > > > One thing I have overlooked completely. > > I appreciate your attention to details but GFP_KERNEL is legit in the > reclaim path. It's been used many years in our production, e.g., > page reclaim > swap_writepage() > frontswap_store() > zswap_frontswap_store() > zswap_entry_cache_alloc(GFP_KERNEL) > > (And I always test my changes with lockdep, kasan, DEBUG_VM, etc., no > warnings ever seen from using GFP_KERNEL in the reclaim path.) OK, I can see it now. __need_reclaim will check for PF_MEMALLOC and skip the fs_reclaim tracking. I still maintain I am not really happy about (nor in the zswap example) allocations from the direct reclaim context. I would really recommend using a pre-allocated pool of objects. If there are strong reasons for not doing so then at lease change that to kzalloc. Thanks! -- Michal Hocko SUSE Labs 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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id BC1CAC433F5 for ; Wed, 12 Jan 2022 10:30:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=PS7eRVKusICmVvEGd9EHnnrBkHnZp+JPTH0qEGnLFX4=; b=ja56loMInuWsLm ITv+lz4E8/yOMmicHnBVm2xwJDMmBX0khNc4xGRyKxBtFVxRE7sYhSh4vVJAhu6l0FYM5D5tDWNBY gELsTgf8dWV9oAmcfh8hnv39/ovesVXQvdS19TPciFFppzz5k5AMBbotVVfC1gB5+ipBFlFiWJHp9 mkjAPotiGaEAQcc3vPseKRXoHft6UH+eNCiYUTCfwzqMYDKqbwmDCTawIv+VzMOvYg4S0AOpsRNt3 7b6n7HnwH8Ys1veNW1Gj+JIF0oL8hzqdeub3WfFOmSLUDs5PHpr0h0w36z6zMZrkpuhglm/9u2hcd nDIiRvvI7QPGyC/NaMqw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1n7asK-0026vo-SH; Wed, 12 Jan 2022 10:29:05 +0000 Received: from smtp-out2.suse.de ([195.135.220.29]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1n7asG-0026tG-9L for linux-arm-kernel@lists.infradead.org; Wed, 12 Jan 2022 10:29:01 +0000 Received: from relay2.suse.de (relay2.suse.de [149.44.160.134]) by smtp-out2.suse.de (Postfix) with ESMTP id EE1A51F3CA; Wed, 12 Jan 2022 10:28:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1641983338; 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=ioyVnpN3K6fNhs+IEe7aVsyN+KrufIvhdGNWWrmI3JA=; b=qA94ONzIs4uB2pR3BTbt8lg3/96/Y38YAMcV7cOYTaUW8EuHvMn5oJsISzeqOjc26MBK/0 H92wU1dghL/np4cg9lwZeon9d2awSYlsbKrolCzdJObL0Zw8ywEXHX4w6vT+gkQ5QjI/H1 cNQn+crVBa9yWVlPheo9PWGsEYHgcz8= Received: from suse.cz (unknown [10.100.201.86]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by relay2.suse.de (Postfix) with ESMTPS id 3E91FA3B83; Wed, 12 Jan 2022 10:28:58 +0000 (UTC) Date: Wed, 12 Jan 2022 11:28:57 +0100 From: Michal Hocko To: Yu Zhao Cc: Andrew Morton , Linus Torvalds , Andi Kleen , Catalin Marinas , Dave Hansen , Hillf Danton , Jens Axboe , Jesse Barnes , Johannes Weiner , Jonathan Corbet , Matthew Wilcox , Mel Gorman , Michael Larabel , Rik van Riel , Vlastimil Babka , Will Deacon , Ying Huang , linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, page-reclaim@google.com, x86@kernel.org, Konstantin Kharlamov Subject: Re: [PATCH v6 6/9] mm: multigenerational lru: aging Message-ID: References: <20220104202227.2903605-1-yuzhao@google.com> <20220104202227.2903605-7-yuzhao@google.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220112_022900_516323_3A5BC9AB X-CRM114-Status: GOOD ( 16.06 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Tue 11-01-22 16:16:57, Yu Zhao wrote: > On Mon, Jan 10, 2022 at 04:01:13PM +0100, Michal Hocko wrote: > > On Thu 06-01-22 17:12:18, Michal Hocko wrote: > > > On Tue 04-01-22 13:22:25, Yu Zhao wrote: > > > > +static struct lru_gen_mm_walk *alloc_mm_walk(void) > > > > +{ > > > > + if (!current->reclaim_state || !current->reclaim_state->mm_walk) > > > > + return kvzalloc(sizeof(struct lru_gen_mm_walk), GFP_KERNEL); > > > > One thing I have overlooked completely. > > I appreciate your attention to details but GFP_KERNEL is legit in the > reclaim path. It's been used many years in our production, e.g., > page reclaim > swap_writepage() > frontswap_store() > zswap_frontswap_store() > zswap_entry_cache_alloc(GFP_KERNEL) > > (And I always test my changes with lockdep, kasan, DEBUG_VM, etc., no > warnings ever seen from using GFP_KERNEL in the reclaim path.) OK, I can see it now. __need_reclaim will check for PF_MEMALLOC and skip the fs_reclaim tracking. I still maintain I am not really happy about (nor in the zswap example) allocations from the direct reclaim context. I would really recommend using a pre-allocated pool of objects. If there are strong reasons for not doing so then at lease change that to kzalloc. Thanks! -- Michal Hocko SUSE Labs _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel