From: Mikulas Patocka <mpatocka@xxxxxxxxxx> commit ca7dc242e358e46d963b32f9d9dd829785a9e957 upstream. dm-writecache has the capability to limit the number of writeback jobs in progress. However, this feature was off by default. As such there were some out-of-memory crashes observed when lowering the low watermark while the cache is full. This commit enables writeback limit by default. It is set to 256MiB or 1/16 of total system memory, whichever is smaller. Cc: stable@xxxxxxxxxxxxxxx Signed-off-by: Mikulas Patocka <mpatocka@xxxxxxxxxx> Signed-off-by: Mike Snitzer <snitzer@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/md/dm-writecache.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/drivers/md/dm-writecache.c +++ b/drivers/md/dm-writecache.c @@ -20,7 +20,7 @@ #define HIGH_WATERMARK 50 #define LOW_WATERMARK 45 -#define MAX_WRITEBACK_JOBS 0 +#define MAX_WRITEBACK_JOBS min(0x10000000 / PAGE_SIZE, totalram_pages() / 16) #define ENDIO_LATENCY 16 #define WRITEBACK_LATENCY 64 #define AUTOCOMMIT_BLOCKS_SSD 65536
