warn when statically-allocated kobjects are used

One of the top ten sysfs problems is that users use statically
allocated kobjects.  This patch reminds them that this is a
naughty thing.

One _really_ nice thing this patch does, is us the kallsyms
mechanism to print out exactly which symbol is being complained
about:

	The kobject at, or inside 'statickobj.2'@(0xc040d020) is not dynamically allocated.

This patch replaces the previous implementation's use of a
_sdata symbol in favor of using kallsyms_lookup().  If a
kobject's address is a resolvable symbol, then it isn't
dynamically allocated.

The one exception to this is init symbols.  The patch also
checks to see whether __init memory has been freed and if
it has will allow kobjects in those sections.

Signed-off-by: Dave Hansen <haveblue@us.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 9 insertions, 0 deletions

diff --git a/init/main.c b/init/main.c
index 844209453c02..17ceaacc96f6 100644
--- a/init/main.c
+++ b/init/main.c
@@ -782,6 +782,14 @@ static void run_init_process(char *init_filename)
 	kernel_execve(init_filename, argv_init, envp_init);
 }
 
+/*
+ * __init/__init_data sections are turned into normal
+ * dynamically allocated memory later in boot.  When
+ * this is 0, the memory is for the __init purposes,
+ * when it it some other value, the memory is dynamic.
+ */
+int initmem_now_dynamic;
+
 /* This is a non __init function. Force it to be noinline otherwise gcc
  * makes it inline to init() and it becomes part of init.text section
  */
@@ -790,6 +798,7 @@ static noinline int init_post(void)
 	/* need to finish all async __init code before freeing the memory */
 	async_synchronize_full();
 	free_initmem();
+	initmem_now_dynamic = 1;
 	unlock_kernel();
 	mark_rodata_ro();
 	system_state = SYSTEM_RUNNING;