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authorHenry Burns <henryburns@google.com>2019-08-13 15:37:25 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2019-08-13 16:06:52 -0700
commitb997052bc3ac444a0bceab1093aff7ae71ed419e (patch)
treefc64a1aff3aa46681dfcedf31c46db09df140996
parent6051d3bd3b91e96c59e62b8be2dba1cc2b19ee40 (diff)
download96b-common-b997052bc3ac444a0bceab1093aff7ae71ed419e.tar.gz
mm/z3fold.c: fix z3fold_destroy_pool() race condition
The constraint from the zpool use of z3fold_destroy_pool() is there are no outstanding handles to memory (so no active allocations), but it is possible for there to be outstanding work on either of the two wqs in the pool. Calling z3fold_deregister_migration() before the workqueues are drained means that there can be allocated pages referencing a freed inode, causing any thread in compaction to be able to trip over the bad pointer in PageMovable(). Link: http://lkml.kernel.org/r/20190726224810.79660-2-henryburns@google.com Fixes: 1f862989b04a ("mm/z3fold.c: support page migration") Signed-off-by: Henry Burns <henryburns@google.com> Reviewed-by: Shakeel Butt <shakeelb@google.com> Reviewed-by: Jonathan Adams <jwadams@google.com> Cc: Vitaly Vul <vitaly.vul@sony.com> Cc: Vitaly Wool <vitalywool@gmail.com> Cc: David Howells <dhowells@redhat.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Henry Burns <henrywolfeburns@gmail.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--mm/z3fold.c5
1 files changed, 4 insertions, 1 deletions
diff --git a/mm/z3fold.c b/mm/z3fold.c
index 43de92f52961..ed19d98c9dcd 100644
--- a/mm/z3fold.c
+++ b/mm/z3fold.c
@@ -817,16 +817,19 @@ out:
static void z3fold_destroy_pool(struct z3fold_pool *pool)
{
kmem_cache_destroy(pool->c_handle);
- z3fold_unregister_migration(pool);
/*
* We need to destroy pool->compact_wq before pool->release_wq,
* as any pending work on pool->compact_wq will call
* queue_work(pool->release_wq, &pool->work).
+ *
+ * There are still outstanding pages until both workqueues are drained,
+ * so we cannot unregister migration until then.
*/
destroy_workqueue(pool->compact_wq);
destroy_workqueue(pool->release_wq);
+ z3fold_unregister_migration(pool);
kfree(pool);
}