The patch titled
Subject: mm/zpool: prevent zbud/zsmalloc from unloading when used
has been removed from the -mm tree. Its filename was
mm-zpool-prevent-zbud-zsmalloc-from-unloading-when-used.patch
This patch was dropped because it is obsolete
------------------------------------------------------
From: Dan Streetman <ddstreet@xxxxxxxx>
Subject: mm/zpool: prevent zbud/zsmalloc from unloading when used
Add try_module_get() to zpool_create_pool(), and module_put() to
zpool_destroy_pool(). Without module usage counting, the driver module(s)
could be unloaded while their pool(s) were active, resulting in an oops
when zpool tried to access them.
Signed-off-by: Dan Streetman <ddstreet@xxxxxxxx>
Cc: Seth Jennings <sjennings@xxxxxxxxxxxxxx>
Cc: Minchan Kim <minchan@xxxxxxxxxx>
Cc: Nitin Gupta <ngupta@xxxxxxxxxx>
Cc: Weijie Yang <weijie.yang@xxxxxxxxxxx>
Reviewed-by: Bob Liu <bob.liu@xxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxx>
Cc: Sergey Senozhatsky <sergey.senozhatsky@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/zpool.h | 5 +++++
mm/zbud.c | 1 +
mm/zpool.c | 22 +++++++++++++++-------
mm/zsmalloc.c | 1 +
4 files changed, 22 insertions(+), 7 deletions(-)
diff -puN include/linux/zpool.h~mm-zpool-prevent-zbud-zsmalloc-from-unloading-when-used include/linux/zpool.h
--- a/include/linux/zpool.h~mm-zpool-prevent-zbud-zsmalloc-from-unloading-when-used
+++ a/include/linux/zpool.h
@@ -176,6 +176,7 @@ u64 zpool_get_total_size(struct zpool *p
*/
struct zpool_driver {
char *type;
+ struct module *owner;
struct list_head list;
void *(*create)(gfp_t gfp, struct zpool_ops *ops);
@@ -203,6 +204,10 @@ void zpool_register_driver(struct zpool_
/**
* zpool_unregister_driver() - unregister a zpool implementation.
* @driver: driver to unregister.
+ *
+ * Module usage counting is used to prevent using a driver
+ * while/after unloading. Please only call unregister from
+ * module exit function.
*/
void zpool_unregister_driver(struct zpool_driver *driver);
diff -puN mm/zbud.c~mm-zpool-prevent-zbud-zsmalloc-from-unloading-when-used mm/zbud.c
--- a/mm/zbud.c~mm-zpool-prevent-zbud-zsmalloc-from-unloading-when-used
+++ a/mm/zbud.c
@@ -184,6 +184,7 @@ static u64 zbud_zpool_total_size(void *p
static struct zpool_driver zbud_zpool_driver = {
.type = "zbud",
+ .owner = THIS_MODULE,
.create = zbud_zpool_create,
.destroy = zbud_zpool_destroy,
.malloc = zbud_zpool_malloc,
diff -puN mm/zpool.c~mm-zpool-prevent-zbud-zsmalloc-from-unloading-when-used mm/zpool.c
--- a/mm/zpool.c~mm-zpool-prevent-zbud-zsmalloc-from-unloading-when-used
+++ a/mm/zpool.c
@@ -72,15 +72,24 @@ static struct zpool_driver *zpool_get_dr
{
struct zpool_driver *driver;
- assert_spin_locked(&drivers_lock);
+ spin_lock(&drivers_lock);
list_for_each_entry(driver, &drivers_head, list) {
- if (!strcmp(driver->type, type))
- return driver;
+ if (!strcmp(driver->type, type)) {
+ bool got = try_module_get(driver->owner);
+ spin_unlock(&drivers_lock);
+ return got ? driver : NULL;
+ }
}
+ spin_unlock(&drivers_lock);
return NULL;
}
+static void zpool_put_driver(struct zpool_driver *driver)
+{
+ module_put(driver->owner);
+}
+
struct zpool *zpool_create_pool(char *type, gfp_t flags,
struct zpool_ops *ops)
{
@@ -89,15 +98,11 @@ struct zpool *zpool_create_pool(char *ty
pr_info("creating pool type %s\n", type);
- spin_lock(&drivers_lock);
driver = zpool_get_driver(type);
- spin_unlock(&drivers_lock);
if (!driver) {
request_module(type);
- spin_lock(&drivers_lock);
driver = zpool_get_driver(type);
- spin_unlock(&drivers_lock);
}
if (!driver) {
@@ -108,6 +113,7 @@ struct zpool *zpool_create_pool(char *ty
zpool = kmalloc(sizeof(*zpool), GFP_KERNEL);
if (!zpool) {
pr_err("couldn't create zpool - out of memory\n");
+ zpool_put_driver(driver);
return NULL;
}
@@ -118,6 +124,7 @@ struct zpool *zpool_create_pool(char *ty
if (!zpool->pool) {
pr_err("couldn't create %s pool\n", type);
+ zpool_put_driver(driver);
kfree(zpool);
return NULL;
}
@@ -139,6 +146,7 @@ void zpool_destroy_pool(struct zpool *zp
list_del(&zpool->list);
spin_unlock(&pools_lock);
zpool->driver->destroy(zpool->pool);
+ zpool_put_driver(zpool->driver);
kfree(zpool);
}
diff -puN mm/zsmalloc.c~mm-zpool-prevent-zbud-zsmalloc-from-unloading-when-used mm/zsmalloc.c
--- a/mm/zsmalloc.c~mm-zpool-prevent-zbud-zsmalloc-from-unloading-when-used
+++ a/mm/zsmalloc.c
@@ -303,6 +303,7 @@ u64 zs_zpool_total_size(void *pool)
static struct zpool_driver zs_zpool_driver = {
.type = "zsmalloc",
+ .owner = THIS_MODULE,
.create = zs_zpool_create,
.destroy = zs_zpool_destroy,
.malloc = zs_zpool_malloc,
_
Patches currently in -mm which might be from ddstreet@xxxxxxxx are
mm-zbud-change-zbud_alloc-size-type-to-size_t.patch
mm-zpool-implement-common-zpool-api-to-zbud-zsmalloc.patch
mm-zpool-zbud-zsmalloc-implement-zpool.patch
mm-zpool-update-zswap-to-use-zpool.patch
mm-zpool-prevent-zbud-zsmalloc-from-unloading-when-used-checkpatch-fixes.patch
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