124 строки
3.9 KiB
C
124 строки
3.9 KiB
C
// SPDX-License-Identifier: GPL-2.0
|
|
/*
|
|
* 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 <linux/kernel.h>
|
|
#include <linux/gfp.h>
|
|
#include <linux/slab.h>
|
|
#include <linux/radix-tree.h>
|
|
#include <stdlib.h>
|
|
#include <stdio.h>
|
|
|
|
#include "regression.h"
|
|
#include "test.h"
|
|
|
|
#define PAGECACHE_TAG_DIRTY XA_MARK_0
|
|
#define PAGECACHE_TAG_WRITEBACK XA_MARK_1
|
|
#define PAGECACHE_TAG_TOWRITE XA_MARK_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];
|
|
|
|
printv(1, "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;
|
|
tag_tagged_items(&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--)
|
|
free(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 */
|
|
free(radix_tree_delete(&mt_tree, max_slots));
|
|
|
|
BUG_ON(!radix_tree_empty(&mt_tree));
|
|
|
|
printv(1, "regression test 2, done\n");
|
|
}
|