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MDEV-23233: Race condition for btr_search_drop_page_hash_index() in buf_page_create()

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commit ad6171b91c (MDEV-22456)
introduced code to buf_page_create() that would lazily drop
adaptive hash index entries for an index that has been
evicted from the data dictionary cache.

Unfortunately, that call was missing adequate protection.
While the btr_search_drop_page_hash_index(block) was executing,
the block could be reused for something else.

buf_page_create(): If btr_search_drop_page_hash_index() must be
invoked, pin the block before releasing the buf_pool->page_hash lock,
so that the block cannot be grabbed by other threads.
This commit is contained in:
Thirunarayanan Balathandayuthapani 2020-07-24 16:52:42 +05:30
parent b4c742108f
commit a1f899a8ab
1 changed files with 17 additions and 2 deletions
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19
storage/innobase/buf/buf0buf.cc
View file

@ -5584,15 +5584,30 @@ buf_page_create(
&& !buf_pool_watch_is_sentinel(buf_pool, &block->page)) {
ut_d(block->page.file_page_was_freed = FALSE);
#ifdef BTR_CUR_HASH_ADAPT
bool drop_hash_entry =
(block->page.state == BUF_BLOCK_FILE_PAGE
&& block->index);
if (drop_hash_entry) {
mutex_enter(&block->mutex);
buf_page_set_sticky(&block->page);
mutex_exit(&block->mutex);
}
#endif
/* Page can be found in buf_pool */
buf_pool_mutex_exit(buf_pool);
rw_lock_x_unlock(hash_lock);
buf_block_free(free_block);
#ifdef BTR_CUR_HASH_ADAPT
if (block->page.state == BUF_BLOCK_FILE_PAGE
&& UNIV_LIKELY_NULL(block->index)) {
if (drop_hash_entry) {
btr_search_drop_page_hash_index(block);
buf_pool_mutex_enter(buf_pool);
mutex_enter(&block->mutex);
buf_page_unset_sticky(&block->page);
mutex_exit(&block->mutex);
buf_pool_mutex_exit(buf_pool);
}
#endif /* BTR_CUR_HASH_ADAPT */