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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id C6709C433F5 for ; Tue, 31 May 2022 15:14:16 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 3A3536B0072; Tue, 31 May 2022 11:14:16 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 34F2D6B0073; Tue, 31 May 2022 11:14:16 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 23F3B6B0074; Tue, 31 May 2022 11:14:16 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) by kanga.kvack.org (Postfix) with ESMTP id 16D616B0072 for ; Tue, 31 May 2022 11:14:16 -0400 (EDT) Received: from smtpin29.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay07.hostedemail.com (Postfix) with ESMTP id D8C6E2056D for ; Tue, 31 May 2022 15:14:15 +0000 (UTC) X-FDA: 79526384070.29.78B1DF2 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by imf26.hostedemail.com (Postfix) with ESMTP id 1CA2D140053 for ; Tue, 31 May 2022 15:14:10 +0000 (UTC) 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 679E9612FC; Tue, 31 May 2022 15:14:14 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8E149C385A9; Tue, 31 May 2022 15:14:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1654010053; bh=gDp6UNdQ0PKd5CJVOD3E4KkUjLefxtxl9Ek4Nl2FAww=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=mXlSXKTpzFFbquqZzqwvtnvCZhcVvGXl02PY5LezepuGRt4lhTakVtteFtu/fd9Uq tZFcfHkNDgyAnRcl5DFxYGxLIM7H1LBOFKqLq9P7sm98S4N+5UnWlFfdQxiZxz7Ucd UJ+lOZhhh026r3qFAob+L+00lWT0uBs5gzXahsvg3pGIz0MFSQEcoYgbK8z9fzHlV0 inW42vMBYRZHhhKKqQ2j6Crh4ojGJo+BaSTHH26CkDTVfZv9GDSypjBwJhSqkY8mZj 5zTz40yuIzjyPwtFikCybZmKtk4bs9TcD/XjmEQOIUbmcBBVzZYCNE801MhFRULDX0 JeF0EOrwiek6g== Date: Tue, 31 May 2022 08:14:12 -0700 From: Jakub Kicinski To: Chen Lin Cc: akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, alexander.duyck@gmail.com, netdev@vger.kernel.org Subject: Re: [PATCH v2] mm: page_frag: Warn_on when frag_alloc size is bigger than PAGE_SIZE Message-ID: <20220531081412.22db88cc@kernel.org> In-Reply-To: <1654008072-3136-1-git-send-email-chen45464546@163.com> References: <20220530122918.549ef054@kernel.org> <1654008072-3136-1-git-send-email-chen45464546@163.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 1CA2D140053 X-Rspam-User: X-Stat-Signature: 5j9amgtnt9sgw7nmr3e6mmmt4sjt7gyt Authentication-Results: imf26.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=mXlSXKTp; dmarc=pass (policy=none) header.from=kernel.org; spf=pass (imf26.hostedemail.com: domain of kuba@kernel.org designates 139.178.84.217 as permitted sender) smtp.mailfrom=kuba@kernel.org X-HE-Tag: 1654010050-766562 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Tue, 31 May 2022 22:41:12 +0800 Chen Lin wrote: > At 2022-05-31 02:29:18, "Jakub Kicinski" wrote: > >Oh, well, the reuse also needs an update. We can slap a similar > >condition next to the pfmemalloc check. > > The sample code above cannot completely solve the current problem. > For example, when fragsz is greater than PAGE_FRAG_CACHE_MAX_SIZE(32768), > __page_frag_cache_refill will return a memory of only 32768 bytes, so > should we continue to expand the PAGE_FRAG_CACHE_MAX_SIZE? Maybe more > work needs to be done Right, but I can think of two drivers off the top of my head which will allocate <=32k frags but none which will allocate more.