From patchwork Fri Dec 15 22:04:17 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Matthew Wilcox X-Patchwork-Id: 10116473 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 2AADA60327 for ; Fri, 15 Dec 2017 22:29:19 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 1CE342A125 for ; Fri, 15 Dec 2017 22:29:19 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 1185F2A1BC; Fri, 15 Dec 2017 22:29:19 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=2.0 tests=BAYES_00,DKIM_SIGNED, RCVD_IN_DNSWL_HI,T_DKIM_INVALID autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 941352A125 for ; Fri, 15 Dec 2017 22:29:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757085AbdLOW1i (ORCPT ); Fri, 15 Dec 2017 17:27:38 -0500 Received: from bombadil.infradead.org ([65.50.211.133]:48669 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756633AbdLOWFX (ORCPT ); Fri, 15 Dec 2017 17:05:23 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=References:In-Reply-To:Message-Id: Date:Subject:Cc:To:From:Sender:Reply-To:MIME-Version:Content-Type: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=twBQxHGEDlYgTOopxV5sYBq1NROUVjylQu/ED/7Eudk=; b=fB0LuqDi/CkVbkHpyCCjEXap8 7BGGcj29rWS9EFd72u/wvpOU0/Bx3IWtM/lB4Uny1fyxici96dijRgo4O8dZbIAMEUriu+efB43tB nnPWLyZDYPvt0COnWgf+VNNU7fl4gFUm4N9VGOBjbN0/JnI0n0ZX4/VS1CbvneRvh9rbQ+J1b85O0 g4JZuAQAnFEqF064grOX0pyx0seXiyFMFhspAvroGmsw9L4JVfcDRa4gQXJz71gbu8Sr6ZIpldwbS X2Kdup/U2isPBOq1UvFTy646j6WrMbiF+C9F/pFTicGepnRt2hLksR02A2ntVGi5+5ck5Qexnu810 tLhDlZ9Rw==; Received: from willy by bombadil.infradead.org with local (Exim 4.87 #1 (Red Hat Linux)) id 1ePy6H-000287-Mx; Fri, 15 Dec 2017 22:05:01 +0000 From: Matthew Wilcox To: linux-kernel@vger.kernel.org Cc: Matthew Wilcox , Ross Zwisler , David Howells , Shaohua Li , Jens Axboe , Rehas Sachdeva , Marc Zyngier , linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-nilfs@vger.kernel.org, linux-btrfs@vger.kernel.org, linux-xfs@vger.kernel.org, linux-usb@vger.kernel.org, linux-raid@vger.kernel.org Subject: [PATCH v5 45/78] shmem: Convert shmem_tag_pins to XArray Date: Fri, 15 Dec 2017 14:04:17 -0800 Message-Id: <20171215220450.7899-46-willy@infradead.org> X-Mailer: git-send-email 2.9.5 In-Reply-To: <20171215220450.7899-1-willy@infradead.org> References: <20171215220450.7899-1-willy@infradead.org> Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Matthew Wilcox Simplify the locking by taking the spinlock while we walk the tree on the assumption that many acquires and releases of the lock will be worse than holding the lock for a (potentially) long time. We could replicate the same locking behaviour with the xarray, but would have to be careful that the xa_node wasn't RCU-freed under us before we took the lock. Signed-off-by: Matthew Wilcox --- mm/shmem.c | 39 ++++++++++++++++----------------------- 1 file changed, 16 insertions(+), 23 deletions(-) diff --git a/mm/shmem.c b/mm/shmem.c index ce285ae635ea..2f41c7ceea18 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -2601,35 +2601,28 @@ static loff_t shmem_file_llseek(struct file *file, loff_t offset, int whence) static void shmem_tag_pins(struct address_space *mapping) { - struct radix_tree_iter iter; - void **slot; - pgoff_t start; + XA_STATE(xas, &mapping->pages, 0); struct page *page; + unsigned int tagged = 0; lru_add_drain(); - start = 0; - rcu_read_lock(); - radix_tree_for_each_slot(slot, &mapping->pages, &iter, start) { - page = radix_tree_deref_slot(slot); - if (!page || radix_tree_exception(page)) { - if (radix_tree_deref_retry(page)) { - slot = radix_tree_iter_retry(&iter); - continue; - } - } else if (page_count(page) - page_mapcount(page) > 1) { - xa_lock_irq(&mapping->pages); - radix_tree_tag_set(&mapping->pages, iter.index, - SHMEM_TAG_PINNED); - xa_unlock_irq(&mapping->pages); - } + xas_lock_irq(&xas); + xas_for_each(&xas, page, ULONG_MAX) { + if (xa_is_value(page)) + continue; + if (page_count(page) - page_mapcount(page) > 1) + xas_set_tag(&xas, SHMEM_TAG_PINNED); - if (need_resched()) { - slot = radix_tree_iter_resume(slot, &iter); - cond_resched_rcu(); - } + if (++tagged % XA_CHECK_SCHED) + continue; + + xas_pause(&xas); + xas_unlock_irq(&xas); + cond_resched(); + xas_lock_irq(&xas); } - rcu_read_unlock(); + xas_unlock_irq(&xas); } /*