Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756484AbcDNOTx (ORCPT ); Thu, 14 Apr 2016 10:19:53 -0400 Received: from mga02.intel.com ([134.134.136.20]:2488 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753980AbcDNOTU (ORCPT ); Thu, 14 Apr 2016 10:19:20 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.24,485,1455004800"; d="scan'208";a="932428285" From: Matthew Wilcox To: linux-kernel@vger.kernel.org, Andrew Morton Cc: Matthew Wilcox , linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, Konstantin Khlebnikov , Kirill Shutemov , Jan Kara , Neil Brown , Ross Zwisler Subject: [PATCH v2 18/29] radix-tree: Fix multiorder BUG_ON in radix_tree_insert Date: Thu, 14 Apr 2016 10:16:39 -0400 Message-Id: <1460643410-30196-19-git-send-email-willy@linux.intel.com> X-Mailer: git-send-email 2.8.0.rc3 In-Reply-To: <1460643410-30196-1-git-send-email-willy@linux.intel.com> References: <1460643410-30196-1-git-send-email-willy@linux.intel.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2607 Lines: 82 These BUG_ON tests are to ensure that all the tags are clear when inserting a new entry. If we insert a multiorder entry, we'll end up looking at the tags for a different node, and so the BUG_ON can end up triggering spuriously. Also, we now have three tags, not two, so check all three are clear, and check all the root tags with a single call to BUG_ON since the bits are stored contiguously. Include a test-case to ensure this problem does not reoccur. Signed-off-by: Matthew Wilcox Reviewed-by: Ross Zwisler --- lib/radix-tree.c | 14 ++++++++++---- tools/testing/radix-tree/multiorder.c | 12 ++++++++++++ 2 files changed, 22 insertions(+), 4 deletions(-) diff --git a/lib/radix-tree.c b/lib/radix-tree.c index f14ada9..ff46042 100644 --- a/lib/radix-tree.c +++ b/lib/radix-tree.c @@ -165,6 +165,11 @@ static inline int root_tag_get(struct radix_tree_root *root, unsigned int tag) return (__force unsigned)root->gfp_mask & (1 << (tag + __GFP_BITS_SHIFT)); } +static inline unsigned root_tags_get(struct radix_tree_root *root) +{ + return (__force unsigned)root->gfp_mask >> __GFP_BITS_SHIFT; +} + /* * Returns 1 if any slot in the node has this tag set. * Otherwise returns 0. @@ -604,12 +609,13 @@ int __radix_tree_insert(struct radix_tree_root *root, unsigned long index, rcu_assign_pointer(*slot, item); if (node) { + unsigned offset = get_slot_offset(node, slot); node->count++; - BUG_ON(tag_get(node, 0, index & RADIX_TREE_MAP_MASK)); - BUG_ON(tag_get(node, 1, index & RADIX_TREE_MAP_MASK)); + BUG_ON(tag_get(node, 0, offset)); + BUG_ON(tag_get(node, 1, offset)); + BUG_ON(tag_get(node, 2, offset)); } else { - BUG_ON(root_tag_get(root, 0)); - BUG_ON(root_tag_get(root, 1)); + BUG_ON(root_tags_get(root)); } return 0; diff --git a/tools/testing/radix-tree/multiorder.c b/tools/testing/radix-tree/multiorder.c index 71f34a0..0a311a5 100644 --- a/tools/testing/radix-tree/multiorder.c +++ b/tools/testing/radix-tree/multiorder.c @@ -81,6 +81,17 @@ static void multiorder_shrink(unsigned long index, int order) item_check_absent(&tree, i); } +static void multiorder_insert_bug(void) +{ + RADIX_TREE(tree, GFP_KERNEL); + + item_insert(&tree, 0); + radix_tree_tag_set(&tree, 0, 0); + item_insert_order(&tree, 3 << 6, 6); + + item_kill_tree(&tree); +} + void multiorder_checks(void) { int i; @@ -94,4 +105,5 @@ void multiorder_checks(void) for (i = 0; i < 15; i++) multiorder_shrink((1UL << (i + RADIX_TREE_MAP_SHIFT)), i); + multiorder_insert_bug(); } -- 2.8.0.rc3