Commit 6b74ab97 authored by Mel Gorman's avatar Mel Gorman Committed by Linus Torvalds
Browse files

mm: add a basic debugging framework for memory initialisation 



Boot initialisation is very complex, with significant numbers of
architecture-specific routines, hooks and code ordering.  While significant
amounts of the initialisation is architecture-independent, it trusts the data
received from the architecture layer.  This is a mistake, and has resulted in
a number of difficult-to-diagnose bugs.

This patchset adds some validation and tracing to memory initialisation.  It
also introduces a few basic defensive measures.  The validation code can be
explicitly disabled for embedded systems.

This patch:

Add additional debugging and verification code for memory initialisation.

Once enabled, the verification checks are always run and when required
additional debugging information may be outputted via a mminit_loglevel=
command-line parameter.

The verification code is placed in a new file mm/mm_init.c.  Ideally other mm
initialisation code will be moved here over time.

Signed-off-by: default avatarMel Gorman <mel@csn.ul.ie>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: Andy Whitcroft <apw@shadowen.org>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 9483a578

Documentation/kernel-parameters.txt

+8 −0
Original line number Diff line number Diff line
@@ -1225,6 +1225,14 @@ and is between 256 and 4096 characters. It is defined in the file 


	mga=		[HW,DRM]



	mminit_loglevel=

			[KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this

			parameter allows control of the logging verbosity for

			the additional memory initialisation checks. A value

			of 0 disables mminit logging and a level of 4 will

			log everything. Information is printed at KERN_DEBUG

			so loglevel=8 may also need to be specified.



	mousedev.tap_time=

			[MOUSE] Maximum time between finger touching and

			leaving touchpad surface for touch to be considered

lib/Kconfig.debug

+12 −0
Original line number Diff line number Diff line
@@ -505,6 +505,18 @@ config DEBUG_WRITECOUNT 


	  If unsure, say N.



config DEBUG_MEMORY_INIT

	bool "Debug memory initialisation" if EMBEDDED

	default !EMBEDDED

	help

	  Enable this for additional checks during memory initialisation.

	  The sanity checks verify aspects of the VM such as the memory model

	  and other information provided by the architecture. Verbose

	  information will be printed at KERN_DEBUG loglevel depending

	  on the mminit_loglevel= command-line option.



	  If unsure, say Y



config DEBUG_LIST

	bool "Debug linked list manipulation"

	depends on DEBUG_KERNEL

mm/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -26,6 +26,7 @@ obj-$(CONFIG_TMPFS_POSIX_ACL) += shmem_acl.o 
obj-$(CONFIG_TINY_SHMEM) += tiny-shmem.o

obj-$(CONFIG_SLOB) += slob.o

obj-$(CONFIG_SLAB) += slab.o

obj-$(CONFIG_DEBUG_MEMORY_INIT) += mm_init.o

obj-$(CONFIG_SLUB) += slub.o

obj-$(CONFIG_MEMORY_HOTPLUG) += memory_hotplug.o

obj-$(CONFIG_FS_XIP) += filemap_xip.o

mm/internal.h

+27 −0
Original line number Diff line number Diff line
@@ -59,4 +59,31 @@ static inline unsigned long page_order(struct page *page) 
#define __paginginit __init

#endif



/* Memory initialisation debug and verification */

enum mminit_level {

	MMINIT_WARNING,

	MMINIT_VERIFY,

	MMINIT_TRACE

};



#ifdef CONFIG_DEBUG_MEMORY_INIT



extern int mminit_loglevel;



#define mminit_dprintk(level, prefix, fmt, arg...) \

do { \

	if (level < mminit_loglevel) { \

		printk(level <= MMINIT_WARNING ? KERN_WARNING : KERN_DEBUG); \

		printk(KERN_CONT "mminit::" prefix " " fmt, ##arg); \

	} \

} while (0)



#else



static inline void mminit_dprintk(enum mminit_level level,

				const char *prefix, const char *fmt, ...)

{

}



#endif /* CONFIG_DEBUG_MEMORY_INIT */

#endif

mm/mm_init.c

0 → 100644
+18 −0
Original line number Diff line number Diff line 
/*

 * mm_init.c - Memory initialisation verification and debugging

 *

 * Copyright 2008 IBM Corporation, 2008

 * Author Mel Gorman <mel@csn.ul.ie>

 *

 */

#include <linux/kernel.h>

#include <linux/init.h>



int __meminitdata mminit_loglevel;



static __init int set_mminit_loglevel(char *str)

{

	get_option(&str, &mminit_loglevel);

	return 0;

}

early_param("mminit_loglevel", set_mminit_loglevel);

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