dm: allocate buffer for messages with small number of arguments using GFP_NOIO
dm-mpath and dm-thin must process messages even if some device is
suspended, so we allocate argv buffer with GFP_NOIO. These messages have
a small fixed number of arguments.
On the other hand, dm-switch needs to process bulk data using messages
so excessive use of GFP_NOIO could cause trouble.
The patch also lowers the default number of arguments from 64 to 8, so
that there is smaller load on GFP_NOIO allocations.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Cc: stable@vger.kernel.org
Acked-by: Alasdair G Kergon <agk@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index 8f87835..41d907b 100644
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -545,14 +545,28 @@
/*
* Used to dynamically allocate the arg array.
+ *
+ * We do first allocation with GFP_NOIO because dm-mpath and dm-thin must
+ * process messages even if some device is suspended. These messages have a
+ * small fixed number of arguments.
+ *
+ * On the other hand, dm-switch needs to process bulk data using messages and
+ * excessive use of GFP_NOIO could cause trouble.
*/
static char **realloc_argv(unsigned *array_size, char **old_argv)
{
char **argv;
unsigned new_size;
+ gfp_t gfp;
- new_size = *array_size ? *array_size * 2 : 64;
- argv = kmalloc(new_size * sizeof(*argv), GFP_KERNEL);
+ if (*array_size) {
+ new_size = *array_size * 2;
+ gfp = GFP_KERNEL;
+ } else {
+ new_size = 8;
+ gfp = GFP_NOIO;
+ }
+ argv = kmalloc(new_size * sizeof(*argv), gfp);
if (argv) {
memcpy(argv, old_argv, *array_size * sizeof(*argv));
*array_size = new_size;