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 418F7C4332F for ; Tue, 21 Dec 2021 08:40:23 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 76C566B007B; Tue, 21 Dec 2021 03:40:22 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 71C496B007D; Tue, 21 Dec 2021 03:40:22 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 60A8B6B007E; Tue, 21 Dec 2021 03:40:22 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0004.hostedemail.com [216.40.44.4]) by kanga.kvack.org (Postfix) with ESMTP id 5155D6B007B for ; Tue, 21 Dec 2021 03:40:22 -0500 (EST) Received: from smtpin11.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 0A0D48A3F4 for ; Tue, 21 Dec 2021 08:40:22 +0000 (UTC) X-FDA: 78941154684.11.4204429 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) by imf26.hostedemail.com (Postfix) with ESMTP id A2803140024 for ; Tue, 21 Dec 2021 08:40:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20210309; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=xTgGXdRhk/J8c5C+wjN+pamdHhw1k/IjmQ+O8umcpLE=; b=mAHY6xQJXk3yN9gApc5WYAdWv4 MBpKl0uCLHdpaf8B7I/j+exPfGWQaKiLTXcG40qXoRa5d8ix1WwYHRSOpvKM/UxCxNfJoG009ov9x F/U5byv2l1OhEQVXkMWYTfOW4n/M+r657oJdcidD4al3A6OPaDJI3I3a5rSU/9yeywi5GbhoOllJf 1V2D5Vz18htUWvrnR8cvWjpJJpITTKPvIYAqRaNnmMFgFp6/WGXjcs/Z/aKU2KcWurDntil7ZrBbR CxQGQyGygnzPpTqIsSsngvtVbK2f5MXxjF+XHPnJZRulRJ3UJ2/ucg7IOpIahZrhCNNHWww0dQ0Vx ootWzaDg==; Received: from hch by bombadil.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1mzagy-005xZe-Tp; Tue, 21 Dec 2021 08:40:16 +0000 Date: Tue, 21 Dec 2021 00:40:16 -0800 From: Christoph Hellwig To: NeilBrown Cc: Trond Myklebust , Anna Schumaker , Chuck Lever , Andrew Morton , Mel Gorman , Christoph Hellwig , David Howells , linux-nfs@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 03/18] MM: use ->swap_rw for reads from SWP_FS_OPS swap-space Message-ID: References: <163969801519.20885.3977673503103544412.stgit@noble.brown> <163969850289.20885.1044395970457169316.stgit@noble.brown> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <163969850289.20885.1044395970457169316.stgit@noble.brown> X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html X-Rspamd-Queue-Id: A2803140024 X-Stat-Signature: ixi5hxi7e9r8ytgyj7bgir1ss8c9zzbx Authentication-Results: imf26.hostedemail.com; dkim=pass header.d=infradead.org header.s=bombadil.20210309 header.b=mAHY6xQJ; dmarc=none; spf=none (imf26.hostedemail.com: domain of BATV+1bb9050bde7847c37d79+6694+infradead.org+hch@bombadil.srs.infradead.org has no SPF policy when checking 198.137.202.133) smtp.mailfrom=BATV+1bb9050bde7847c37d79+6694+infradead.org+hch@bombadil.srs.infradead.org X-Rspamd-Server: rspam11 X-HE-Tag: 1640076021-926420 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: > +int sio_pool_init(void) > +{ > + if (!sio_pool) > + sio_pool = mempool_create_kmalloc_pool( > + SWAP_CLUSTER_MAX, sizeof(struct swap_iocb)); I can't see anything serializing access here, so we'll need a lock or cmpxchg dance. > + if (sio_pool) > + return 0; > + else > + return -ENOMEM; Nit: This would flow much nicer as: if (!sio_pool) return -ENOMEM; return 0; > int swap_readpage(struct page *page, bool synchronous) > { > struct bio *bio; > @@ -378,13 +412,25 @@ int swap_readpage(struct page *page, bool synchronous) > } > > if (data_race(sis->flags & SWP_FS_OPS)) { > - //struct file *swap_file = sis->swap_file; > - //struct address_space *mapping = swap_file->f_mapping; This should not be left by the previous patch. In fact I suspect the part of the previous patch that adds ->swap_rw should probably be folded into this patch. > + struct file *swap_file = sis->swap_file; > + struct address_space *mapping = swap_file->f_mapping; > + struct iov_iter from; > + struct swap_iocb *sio; > + loff_t pos = page_file_offset(page); > + > + sio = mempool_alloc(sio_pool, GFP_KERNEL); > + init_sync_kiocb(&sio->iocb, swap_file); > + sio->iocb.ki_pos = pos; > + sio->iocb.ki_complete = sio_read_complete; > + sio->bvec.bv_page = page; > + sio->bvec.bv_len = PAGE_SIZE; > + sio->bvec.bv_offset = 0; > + > + iov_iter_bvec(&from, READ, &sio->bvec, 1, PAGE_SIZE); > + ret = mapping->a_ops->swap_rw(&sio->iocb, &from); > + if (ret != -EIOCBQUEUED) > + sio_read_complete(&sio->iocb, ret); > > goto out; I'd be tempted to split the SWP_FS_OPS into a helper to keep the code tidy.