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authorHenry Burns <henryburns@google.com>2019-08-13 15:37:21 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2019-08-13 16:06:52 -0700
commit6051d3bd3b91e96c59e62b8be2dba1cc2b19ee40 (patch)
treed920fb174a331f3072ce04fd508d3eba566ac801 /mm/z3fold.c
parenta53190a4aaa36494f4d7209fd1fcc6f2ee08e0e0 (diff)
mm/z3fold.c: fix z3fold_destroy_pool() ordering
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. If there is work queued on pool->compact_workqueue when it is called, z3fold_destroy_pool() will do: z3fold_destroy_pool() destroy_workqueue(pool->release_wq) destroy_workqueue(pool->compact_wq) drain_workqueue(pool->compact_wq) do_compact_page(zhdr) kref_put(&zhdr->refcount) __release_z3fold_page(zhdr, ...) queue_work_on(pool->release_wq, &pool->work) *BOOM* So compact_wq needs to be destroyed before release_wq. Link: http://lkml.kernel.org/r/20190726224810.79660-1-henryburns@google.com Fixes: 5d03a6613957 ("mm/z3fold.c: use kref to prevent page free/compact race") 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>
Diffstat (limited to 'mm/z3fold.c')
-rw-r--r--mm/z3fold.c9
1 files changed, 8 insertions, 1 deletions
diff --git a/mm/z3fold.c b/mm/z3fold.c
index 1a029a7432ee..43de92f52961 100644
--- a/mm/z3fold.c
+++ b/mm/z3fold.c
@@ -818,8 +818,15 @@ static void z3fold_destroy_pool(struct z3fold_pool *pool)
{
kmem_cache_destroy(pool->c_handle);
z3fold_unregister_migration(pool);
- destroy_workqueue(pool->release_wq);
+
+ /*
+ * 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).
+ */
+
destroy_workqueue(pool->compact_wq);
+ destroy_workqueue(pool->release_wq);
kfree(pool);
}