block/partitions: optimize memory allocation in check_partition()
Currently, sizeof(struct parsed_partitions) may be 64KB in 32bit arch, so
it is easy to trigger page allocation failure by check_partition,
especially in hotplug block device situation(such as, USB mass storage,
MMC card, ...), and Felipe Balbi has observed the failure.
This patch does below optimizations on the allocation of struct
parsed_partitions to try to address the issue:
- make parsed_partitions.parts as pointer so that the pointed memory can
fit in 32KB buffer, then approximate 32KB memory can be saved
- vmalloc the buffer pointed by parsed_partitions.parts because 32KB is
still a bit big for kmalloc
- given that many devices have the partition count limit, so only
allocate disk_max_parts() partitions instead of 256 partitions always
Signed-off-by: Ming Lei <ming.lei@canonical.com>
Reported-by: Felipe Balbi <balbi@ti.com>
Cc: Jens Axboe <axboe@kernel.dk>
Reviewed-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/block/partitions/check.c b/block/partitions/check.c
index bc90867..19ba207 100644
--- a/block/partitions/check.c
+++ b/block/partitions/check.c
@@ -14,6 +14,7 @@
*/
#include <linux/slab.h>
+#include <linux/vmalloc.h>
#include <linux/ctype.h>
#include <linux/genhd.h>
@@ -106,18 +107,45 @@
NULL
};
+static struct parsed_partitions *allocate_partitions(struct gendisk *hd)
+{
+ struct parsed_partitions *state;
+ int nr;
+
+ state = kzalloc(sizeof(*state), GFP_KERNEL);
+ if (!state)
+ return NULL;
+
+ nr = disk_max_parts(hd);
+ state->parts = vzalloc(nr * sizeof(state->parts[0]));
+ if (!state->parts) {
+ kfree(state);
+ return NULL;
+ }
+
+ state->limit = nr;
+
+ return state;
+}
+
+void free_partitions(struct parsed_partitions *state)
+{
+ vfree(state->parts);
+ kfree(state);
+}
+
struct parsed_partitions *
check_partition(struct gendisk *hd, struct block_device *bdev)
{
struct parsed_partitions *state;
int i, res, err;
- state = kzalloc(sizeof(struct parsed_partitions), GFP_KERNEL);
+ state = allocate_partitions(hd);
if (!state)
return NULL;
state->pp_buf = (char *)__get_free_page(GFP_KERNEL);
if (!state->pp_buf) {
- kfree(state);
+ free_partitions(state);
return NULL;
}
state->pp_buf[0] = '\0';
@@ -128,10 +156,9 @@
if (isdigit(state->name[strlen(state->name)-1]))
sprintf(state->name, "p");
- state->limit = disk_max_parts(hd);
i = res = err = 0;
while (!res && check_part[i]) {
- memset(&state->parts, 0, sizeof(state->parts));
+ memset(state->parts, 0, state->limit * sizeof(state->parts[0]));
res = check_part[i++](state);
if (res < 0) {
/* We have hit an I/O error which we don't report now.
@@ -161,6 +188,6 @@
printk(KERN_INFO "%s", state->pp_buf);
free_page((unsigned long)state->pp_buf);
- kfree(state);
+ free_partitions(state);
return ERR_PTR(res);
}