diff options
author | Keith Bostic <keith.bostic@mongodb.com> | 2017-06-26 03:04:00 -0400 |
---|---|---|
committer | Alex Gorrod <alexander.gorrod@mongodb.com> | 2017-06-27 10:44:44 +1000 |
commit | b8f590dea0400666ef26e21adf11c5997bb5ef1b (patch) | |
tree | 96df6d8f34e69ee9a3bfe257157e885ddc599788 | |
parent | 534677a2eab033bf817588704417bb25f0d19551 (diff) | |
download | mongo-b8f590dea0400666ef26e21adf11c5997bb5ef1b.tar.gz |
WT-3373 Access violation due to a bug in internal page splitting (#3478)mongodb-3.2.16mongodb-3.2.15
When acquiring a lock on our parent internal page, we use the WT_REF.home
field to reference our parent page. As a child of the parent page, we
prevent its eviction, but that's a weak guarantee. If the parent page
splits, and our WT_REF were to move with the split, the WT_REF.home field
might change underneath us and we could race, and end up attempting to
access an evicted page. Set the session page-index generation so if the
parent splits, it still can't be evicted.
-rw-r--r-- | src/btree/bt_split.c | 32 |
1 files changed, 29 insertions, 3 deletions
diff --git a/src/btree/bt_split.c b/src/btree/bt_split.c index 627e6b9cb48..92be2125b88 100644 --- a/src/btree/bt_split.c +++ b/src/btree/bt_split.c @@ -1256,12 +1256,12 @@ err: switch (complete) { } /* - * __split_internal_lock -- + * __split_internal_lock_worker -- * Lock an internal page. */ static int -__split_internal_lock(WT_SESSION_IMPL *session, WT_REF *ref, bool trylock, - WT_PAGE **parentp, bool *hazardp) +__split_internal_lock_worker(WT_SESSION_IMPL *session, + WT_REF *ref, bool trylock, WT_PAGE **parentp, bool *hazardp) { WT_DECL_RET; WT_PAGE *parent; @@ -1340,6 +1340,32 @@ err: WT_PAGE_UNLOCK(session, parent); } /* + * __split_internal_lock -- + * Lock an internal page. + */ +static int +__split_internal_lock(WT_SESSION_IMPL *session, + WT_REF *ref, bool trylock, WT_PAGE **parentp, bool *hazardp) +{ + WT_DECL_RET; + + /* + * There's no lock on our parent page and we're about to acquire one, + * which implies using the WT_REF.home field to reference our parent + * page. As a child of the parent page, we prevent its eviction, but + * that's a weak guarantee. If the parent page splits, and our WT_REF + * were to move with the split, the WT_REF.home field might change + * underneath us and we could race, and end up attempting to access + * an evicted page. Set the session page-index generation so if the + * parent splits, it still can't be evicted. + */ + WT_WITH_PAGE_INDEX(session, + ret = __split_internal_lock_worker( + session, ref, trylock, parentp, hazardp)); + return (ret); +} + +/* * __split_internal_unlock -- * Unlock the parent page. */ |