From 5233c47c8d468be88ae594d2fd19e89f321bf419 Mon Sep 17 00:00:00 2001 From: Mikulas Patocka Date: Wed, 10 Feb 2021 15:26:23 -0500 Subject: dm: fix deadlock when swapping to encrypted device commit a666e5c05e7c4aaabb2c5d58117b0946803d03d2 upstream. The system would deadlock when swapping to a dm-crypt device. The reason is that for each incoming write bio, dm-crypt allocates memory that holds encrypted data. These excessive allocations exhaust all the memory and the result is either deadlock or OOM trigger. This patch limits the number of in-flight swap bios, so that the memory consumed by dm-crypt is limited. The limit is enforced if the target set the "limit_swap_bios" variable and if the bio has REQ_SWAP set. Non-swap bios are not affected becuase taking the semaphore would cause performance degradation. This is similar to request-based drivers - they will also block when the number of requests is over the limit. Signed-off-by: Mikulas Patocka Cc: stable@vger.kernel.org Signed-off-by: Mike Snitzer Signed-off-by: Greg Kroah-Hartman --- include/linux/device-mapper.h | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'include') diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h index e4e1f5c1f492..a53d7d2c2d95 100644 --- a/include/linux/device-mapper.h +++ b/include/linux/device-mapper.h @@ -316,6 +316,11 @@ struct dm_target { * whether or not its underlying devices have support. */ bool discards_supported:1; + + /* + * Set if we need to limit the number of in-flight bios when swapping. + */ + bool limit_swap_bios:1; }; /* Each target can link one of these into the table */ -- cgit v1.2.3