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authorMikulas Patocka <mpatocka@redhat.com>2021-02-10 23:26:23 +0300
committerMike Snitzer <snitzer@redhat.com>2021-02-11 17:45:28 +0300
commita666e5c05e7c4aaabb2c5d58117b0946803d03d2 (patch)
tree1a9dc24b70359cd4f268966d99763d79bea28926 /include/linux/device-mapper.h
parente3290b9491ff5b7ee40f9e0a4c06821988a2a2bf (diff)
downloadlinux-a666e5c05e7c4aaabb2c5d58117b0946803d03d2.tar.xz
dm: fix deadlock when swapping to encrypted device
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 <mpatocka@redhat.com> Cc: stable@vger.kernel.org Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Diffstat (limited to 'include/linux/device-mapper.h')
-rw-r--r--include/linux/device-mapper.h5
1 files changed, 5 insertions, 0 deletions
diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h
index c98d847b0f0b..7f4ac87c0b32 100644
--- a/include/linux/device-mapper.h
+++ b/include/linux/device-mapper.h
@@ -343,6 +343,11 @@ 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;
};
void *dm_per_bio_data(struct bio *bio, size_t data_size);