From: Milan Broz <mbroz@redhat.com>

Add cond_resched() to prevent monopolising CPU when processing large bios.

dm-crypt processes encryption of bios in sector units.  If the bio request
is big it can spend a long time in the encryption call.

(akpm: needed in 2.6.26 and, given that it fixes soft-lockup warnings,
needed in -stable too)

Signed-off-by: Milan Broz <mbroz@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Tested-by: Yan Li <elliot.li.tech@gmail.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

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

diff -puN drivers/md/dm-crypt.c~dm-crypt-add-cond_resched-to-crypt_convert drivers/md/dm-crypt.c
--- a/drivers/md/dm-crypt.c~dm-crypt-add-cond_resched-to-crypt_convert
+++ a/drivers/md/dm-crypt.c
@@ -432,6 +432,7 @@ static int crypt_convert(struct crypt_co
 		case 0:
 			atomic_dec(&ctx->pending);
 			ctx->sector++;
+			cond_resched();
 			continue;
 
 		/* error */
_