From 1366c37ed84b166a0fffe201154b0d3b78a3976b Mon Sep 17 00:00:00 2001 From: Matthew Wilcox Date: Thu, 17 Mar 2016 14:21:45 -0700 Subject: radix tree test harness This code is mostly from Andrew Morton and Nick Piggin; tarball downloaded from http://ozlabs.org/~akpm/rtth.tar.gz with sha1sum 0ce679db9ec047296b5d1ff7a1dfaa03a7bef1bd Some small modifications were necessary to the test harness to fix the build with the current Linux source code. I also made minor modifications to automatically test the radix-tree.c and radix-tree.h files that are in the current source tree, as opposed to a copied and slightly modified version. I am sure more could be done to tidy up the harness, as well as adding more tests. [koct9i@gmail.com: fix compilation] Signed-off-by: Matthew Wilcox Cc: Shuah Khan Cc: Johannes Weiner Cc: Matthew Wilcox Cc: "Kirill A. Shutemov" Cc: Ross Zwisler Cc: Hugh Dickins Signed-off-by: Konstantin Khlebnikov Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- tools/testing/radix-tree/regression2.c | 126 +++++++++++++++++++++++++++++++++ 1 file changed, 126 insertions(+) create mode 100644 tools/testing/radix-tree/regression2.c (limited to 'tools/testing/radix-tree/regression2.c') diff --git a/tools/testing/radix-tree/regression2.c b/tools/testing/radix-tree/regression2.c new file mode 100644 index 000000000000..5d2fa28cdca3 --- /dev/null +++ b/tools/testing/radix-tree/regression2.c @@ -0,0 +1,126 @@ +/* + * Regression2 + * Description: + * Toshiyuki Okajima describes the following radix-tree bug: + * + * In the following case, we can get a hangup on + * radix_radix_tree_gang_lookup_tag_slot. + * + * 0. The radix tree contains RADIX_TREE_MAP_SIZE items. And the tag of + * a certain item has PAGECACHE_TAG_DIRTY. + * 1. radix_tree_range_tag_if_tagged(, start, end, , PAGECACHE_TAG_DIRTY, + * PAGECACHE_TAG_TOWRITE) is called to add PAGECACHE_TAG_TOWRITE tag + * for the tag which has PAGECACHE_TAG_DIRTY. However, there is no tag with + * PAGECACHE_TAG_DIRTY within the range from start to end. As the result, + * There is no tag with PAGECACHE_TAG_TOWRITE but the root tag has + * PAGECACHE_TAG_TOWRITE. + * 2. An item is added into the radix tree and then the level of it is + * extended into 2 from 1. At that time, the new radix tree node succeeds + * the tag status of the root tag. Therefore the tag of the new radix tree + * node has PAGECACHE_TAG_TOWRITE but there is not slot with + * PAGECACHE_TAG_TOWRITE tag in the child node of the new radix tree node. + * 3. The tag of a certain item is cleared with PAGECACHE_TAG_DIRTY. + * 4. All items within the index range from 0 to RADIX_TREE_MAP_SIZE - 1 are + * released. (Only the item which index is RADIX_TREE_MAP_SIZE exist in the + * radix tree.) As the result, the slot of the radix tree node is NULL but + * the tag which corresponds to the slot has PAGECACHE_TAG_TOWRITE. + * 5. radix_tree_gang_lookup_tag_slot(PAGECACHE_TAG_TOWRITE) calls + * __lookup_tag. __lookup_tag returns with 0. And __lookup_tag doesn't + * change the index that is the input and output parameter. Because the 1st + * slot of the radix tree node is NULL, but the tag which corresponds to + * the slot has PAGECACHE_TAG_TOWRITE. + * Therefore radix_tree_gang_lookup_tag_slot tries to get some items by + * calling __lookup_tag, but it cannot get any items forever. + * + * The fix is to change that radix_tree_tag_if_tagged doesn't tag the root tag + * if it doesn't set any tags within the specified range. + * + * Running: + * This test should run to completion immediately. The above bug would cause it + * to hang indefinitely. + * + * Upstream commit: + * Not yet + */ +#include +#include +#include +#include +#include +#include + +#include "regression.h" + +#ifdef __KERNEL__ +#define RADIX_TREE_MAP_SHIFT (CONFIG_BASE_SMALL ? 4 : 6) +#else +#define RADIX_TREE_MAP_SHIFT 3 /* For more stressful testing */ +#endif + +#define RADIX_TREE_MAP_SIZE (1UL << RADIX_TREE_MAP_SHIFT) +#define PAGECACHE_TAG_DIRTY 0 +#define PAGECACHE_TAG_WRITEBACK 1 +#define PAGECACHE_TAG_TOWRITE 2 + +static RADIX_TREE(mt_tree, GFP_KERNEL); +unsigned long page_count = 0; + +struct page { + unsigned long index; +}; + +static struct page *page_alloc(void) +{ + struct page *p; + p = malloc(sizeof(struct page)); + p->index = page_count++; + + return p; +} + +void regression2_test(void) +{ + int i; + struct page *p; + int max_slots = RADIX_TREE_MAP_SIZE; + unsigned long int start, end; + struct page *pages[1]; + + printf("running regression test 2 (should take milliseconds)\n"); + /* 0. */ + for (i = 0; i <= max_slots - 1; i++) { + p = page_alloc(); + radix_tree_insert(&mt_tree, i, p); + } + radix_tree_tag_set(&mt_tree, max_slots - 1, PAGECACHE_TAG_DIRTY); + + /* 1. */ + start = 0; + end = max_slots - 2; + radix_tree_range_tag_if_tagged(&mt_tree, &start, end, 1, + PAGECACHE_TAG_DIRTY, PAGECACHE_TAG_TOWRITE); + + /* 2. */ + p = page_alloc(); + radix_tree_insert(&mt_tree, max_slots, p); + + /* 3. */ + radix_tree_tag_clear(&mt_tree, max_slots - 1, PAGECACHE_TAG_DIRTY); + + /* 4. */ + for (i = max_slots - 1; i >= 0; i--) + radix_tree_delete(&mt_tree, i); + + /* 5. */ + // NOTE: start should not be 0 because radix_tree_gang_lookup_tag_slot + // can return. + start = 1; + end = max_slots - 2; + radix_tree_gang_lookup_tag_slot(&mt_tree, (void ***)pages, start, end, + PAGECACHE_TAG_TOWRITE); + + /* We remove all the remained nodes */ + radix_tree_delete(&mt_tree, max_slots); + + printf("regression test 2, done\n"); +} -- cgit v1.2.3-59-g8ed1b