call_usermodehelper(): increase reliability

Presently call_usermodehelper_setup() uses GFP_ATOMIC.  but it can return
NULL _very_ easily.

GFP_ATOMIC is needed only when we can't sleep.  and, GFP_KERNEL is robust
and better.

thus, I add gfp_mask argument to call_usermodehelper_setup().

So, its callers pass the gfp_t as below:

call_usermodehelper() and call_usermodehelper_keys():
	depend on 'wait' argument.
call_usermodehelper_pipe():
	always GFP_KERNEL because always run under process context.
orderly_poweroff():
	pass to GFP_ATOMIC because may run under interrupt context.

Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: "Paul Menage" <menage@google.com>
Reviewed-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Andi Kleen <andi@firstfloor.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 6 insertions, 5 deletions

diff --git a/kernel/kmod.c b/kernel/kmod.c
index 2989f67c4446..2456d1a0befb 100644
--- a/kernel/kmod.c
+++ b/kernel/kmod.c
@@ -352,16 +352,17 @@ static inline void register_pm_notifier_callback(void) {}
  * @path: path to usermode executable
  * @argv: arg vector for process
  * @envp: environment for process
+ * @gfp_mask: gfp mask for memory allocation
  *
  * Returns either %NULL on allocation failure, or a subprocess_info
  * structure.  This should be passed to call_usermodehelper_exec to
  * exec the process and free the structure.
  */
-struct subprocess_info *call_usermodehelper_setup(char *path,
-                                                  char **argv, char **envp)
+struct subprocess_info *call_usermodehelper_setup(char *path, char **argv,
+                                                  char **envp, gfp_t gfp_mask)
 {
         struct subprocess_info *sub_info;
-        sub_info = kzalloc(sizeof(struct subprocess_info),  GFP_ATOMIC);
+        sub_info = kzalloc(sizeof(struct subprocess_info), gfp_mask);
         if (!sub_info)
                 goto out;
 
@@ -494,7 +495,7 @@ int call_usermodehelper_pipe(char *path, char **argv, char **envp,
         struct subprocess_info *sub_info;
         int ret;
 
-        sub_info = call_usermodehelper_setup(path, argv, envp);
+        sub_info = call_usermodehelper_setup(path, argv, envp, GFP_KERNEL);
         if (sub_info == NULL)
                 return -ENOMEM;
 
diff --git a/kernel/sys.c b/kernel/sys.c
index 14e97282eb6c..6c2188046048 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -1795,7 +1795,7 @@ int orderly_poweroff(bool force)
                 goto out;
         }
 
-        info = call_usermodehelper_setup(argv[0], argv, envp);
+        info = call_usermodehelper_setup(argv[0], argv, envp, GFP_ATOMIC);
         if (info == NULL) {
                 argv_free(argv);
                 goto out;