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 X-Spam-Level: X-Spam-Status: No, score=-0.6 required=3.0 tests=DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,T_DKIM_INVALID, URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 43224C433EF for ; Sun, 17 Jun 2018 02:07:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id F20322086A for ; Sun, 17 Jun 2018 02:07:14 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="mnOUCgq4" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org F20322086A Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934742AbeFQCHM (ORCPT ); Sat, 16 Jun 2018 22:07:12 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:59476 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934051AbeFQCBO (ORCPT ); Sat, 16 Jun 2018 22:01:14 -0400 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=taP8BwheHg3CEkDXuvl7b4R9WQ7b3YzBrhJkOgu4qeA=; b=mnOUCgq42hLXgcqQvdSJolBa4 M2pHHerVUVQEAix/TXoPd/ZLNBXq46cwsAlwSXV34gaKqxdjMLDbIBuoLXtyO82BlJoMu8EfMh9ux pU3APwkzHc+vWtyGCLTLQ0cASLWRek2CsfN52jLPIlRjl9TV8tFIG/BNt6M9s9LZtM+AhKQ7EzJAp Y0JCImZZCPzVXB8OH2ekbiLa4xE5a2zPEzVoiptNgLCITKe5yxa70ZBRvxCZSbxxWiBqH4a2eOYWC +vtRoNDpb/8Lt7UHE2Cbqt6i3VnUNVTgVl8WLCtiLvyowoAKYnhgT5Dk3nnSM+cKTl0E7N2qZ6y0Q a/tTBK1sw==; Received: from willy by bombadil.infradead.org with local (Exim 4.90_1 #2 (Red Hat Linux)) id 1fUN0C-0001S2-0j; Sun, 17 Jun 2018 02:01:12 +0000 From: Matthew Wilcox To: linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Matthew Wilcox , Jan Kara , Jeff Layton , Lukas Czerner , Ross Zwisler , Christoph Hellwig , Goldwyn Rodrigues , Nicholas Piggin , Ryusuke Konishi , linux-nilfs@vger.kernel.org, Jaegeuk Kim , Chao Yu , linux-f2fs-devel@lists.sourceforge.net Subject: [PATCH v14 54/74] memfd: Convert memfd_wait_for_pins to XArray Date: Sat, 16 Jun 2018 19:00:32 -0700 Message-Id: <20180617020052.4759-55-willy@infradead.org> X-Mailer: git-send-email 2.14.3 In-Reply-To: <20180617020052.4759-1-willy@infradead.org> References: <20180617020052.4759-1-willy@infradead.org> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 while we process an entire batch of pages. Signed-off-by: Matthew Wilcox Reviewed-by: Mike Kravetz --- mm/memfd.c | 61 ++++++++++++++++++++++-------------------------------- 1 file changed, 25 insertions(+), 36 deletions(-) diff --git a/mm/memfd.c b/mm/memfd.c index 27069518e3c5..e7d6be725b7a 100644 --- a/mm/memfd.c +++ b/mm/memfd.c @@ -21,7 +21,7 @@ #include /* - * We need a tag: a new tag would expand every radix_tree_node by 8 bytes, + * We need a tag: a new tag would expand every xa_node by 8 bytes, * so reuse a tag which we firmly believe is never set or cleared on tmpfs * or hugetlbfs because they are memory only filesystems. */ @@ -72,9 +72,7 @@ static void memfd_tag_pins(struct address_space *mapping) */ static int memfd_wait_for_pins(struct address_space *mapping) { - struct radix_tree_iter iter; - void __rcu **slot; - pgoff_t start; + XA_STATE(xas, &mapping->i_pages, 0); struct page *page; int error, scan; @@ -82,7 +80,9 @@ static int memfd_wait_for_pins(struct address_space *mapping) error = 0; for (scan = 0; scan <= LAST_SCAN; scan++) { - if (!radix_tree_tagged(&mapping->i_pages, MEMFD_TAG_PINNED)) + unsigned int tagged = 0; + + if (!xas_tagged(&xas, MEMFD_TAG_PINNED)) break; if (!scan) @@ -90,45 +90,34 @@ static int memfd_wait_for_pins(struct address_space *mapping) else if (schedule_timeout_killable((HZ << scan) / 200)) scan = LAST_SCAN; - start = 0; - rcu_read_lock(); - radix_tree_for_each_tagged(slot, &mapping->i_pages, &iter, - start, MEMFD_TAG_PINNED) { - - page = radix_tree_deref_slot(slot); - if (radix_tree_exception(page)) { - if (radix_tree_deref_retry(page)) { - slot = radix_tree_iter_retry(&iter); - continue; - } - - page = NULL; - } - - if (page && - page_count(page) - page_mapcount(page) != 1) { - if (scan < LAST_SCAN) - goto continue_resched; - + xas_set(&xas, 0); + xas_lock_irq(&xas); + xas_for_each_tagged(&xas, page, ULONG_MAX, MEMFD_TAG_PINNED) { + bool clear = true; + if (xa_is_value(page)) + continue; + if (page_count(page) - page_mapcount(page) != 1) { /* * On the last scan, we clean up all those tags * we inserted; but make a note that we still * found pages pinned. */ - error = -EBUSY; + if (scan == LAST_SCAN) + error = -EBUSY; + else + clear = false; } + if (clear) + xas_clear_tag(&xas, MEMFD_TAG_PINNED); + if (++tagged % XA_CHECK_SCHED) + continue; - xa_lock_irq(&mapping->i_pages); - radix_tree_tag_clear(&mapping->i_pages, - iter.index, MEMFD_TAG_PINNED); - xa_unlock_irq(&mapping->i_pages); -continue_resched: - if (need_resched()) { - slot = radix_tree_iter_resume(slot, &iter); - cond_resched_rcu(); - } + xas_pause(&xas); + xas_unlock_irq(&xas); + cond_resched(); + xas_lock_irq(&xas); } - rcu_read_unlock(); + xas_unlock_irq(&xas); } return error; -- 2.17.1