[2.6.22.2 review 45/84] dm io: fix panic on large request

[Greg KH]

From: Milan Broz <mbroz@xxxxxxxxxx>

Flush workqueue before releasing bioset and mopools in dm-crypt.  There can
be finished but not yet released request.

Call chain causing oops:
  run workqueue
    dec_pending
      bio_endio(...);
      	<remove device request - remove mempool>
      mempool_free(io, cc->io_pool);

This usually happens when cryptsetup create temporary
luks mapping in the beggining of crypt device activation.

When dm-core calls destructor crypt_dtr, no new request
are possible.

Signed-off-by: Milan Broz <mbroz@xxxxxxxxxx>
Cc: Chuck Ebbert <cebbert@xxxxxxxxxx>
Cc: Patrick McHardy <kaber@xxxxxxxxx>
Acked-by: Alasdair G Kergon <agk@xxxxxxxxxx>
Cc: Christophe Saout <christophe@xxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>

---
 drivers/md/dm-crypt.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/drivers/md/dm-crypt.c
+++ b/drivers/md/dm-crypt.c
@@ -920,6 +920,8 @@ static void crypt_dtr(struct dm_target *
 {
 	struct crypt_config *cc = (struct crypt_config *) ti->private;
 
+	flush_workqueue(_kcryptd_workqueue);
+
 	bioset_free(cc->bs);
 	mempool_destroy(cc->page_pool);
 	mempool_destroy(cc->io_pool);

-- 
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