Commit e30825f1 authored by Joonsoo Kim's avatar Joonsoo Kim Committed by Linus Torvalds
Browse files

mm/debug-pagealloc: prepare boottime configurable on/off 



Until now, debug-pagealloc needs extra flags in struct page, so we need to
recompile whole source code when we decide to use it.  This is really
painful, because it takes some time to recompile and sometimes rebuild is
not possible due to third party module depending on struct page.  So, we
can't use this good feature in many cases.

Now, we have the page extension feature that allows us to insert extra
flags to outside of struct page.  This gets rid of third party module
issue mentioned above.  And, this allows us to determine if we need extra
memory for this page extension in boottime.  With these property, we can
avoid using debug-pagealloc in boottime with low computational overhead in
the kernel built with CONFIG_DEBUG_PAGEALLOC.  This will help our
development process greatly.

This patch is the preparation step to achive above goal.  debug-pagealloc
originally uses extra field of struct page, but, after this patch, it will
use field of struct page_ext.  Because memory for page_ext is allocated
later than initialization of page allocator in CONFIG_SPARSEMEM, we should
disable debug-pagealloc feature temporarily until initialization of
page_ext.  This patch implements this.

Signed-off-by: default avatarJoonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Dave Hansen <dave@sr71.net>
Cc: Michal Nazarewicz <mina86@mina86.com>
Cc: Jungsoo Son <jungsoo.son@lge.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent eefa864b

include/linux/mm.h

+18 −1
Original line number Diff line number Diff line
@@ -19,6 +19,7 @@ 
#include <linux/bit_spinlock.h>

#include <linux/shrinker.h>

#include <linux/resource.h>

#include <linux/page_ext.h>



struct mempolicy;

struct anon_vma;
@@ -2155,20 +2156,36 @@ extern void copy_user_huge_page(struct page *dst, struct page *src, 
				unsigned int pages_per_huge_page);

#endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLBFS */



extern struct page_ext_operations debug_guardpage_ops;

extern struct page_ext_operations page_poisoning_ops;



#ifdef CONFIG_DEBUG_PAGEALLOC

extern unsigned int _debug_guardpage_minorder;

extern bool _debug_guardpage_enabled;



static inline unsigned int debug_guardpage_minorder(void)

{

	return _debug_guardpage_minorder;

}



static inline bool debug_guardpage_enabled(void)

{

	return _debug_guardpage_enabled;

}



static inline bool page_is_guard(struct page *page)

{

	return test_bit(PAGE_DEBUG_FLAG_GUARD, &page->debug_flags);

	struct page_ext *page_ext;



	if (!debug_guardpage_enabled())

		return false;



	page_ext = lookup_page_ext(page);

	return test_bit(PAGE_EXT_DEBUG_GUARD, &page_ext->flags);

}

#else

static inline unsigned int debug_guardpage_minorder(void) { return 0; }

static inline bool debug_guardpage_enabled(void) { return false; }

static inline bool page_is_guard(struct page *page) { return false; }

#endif /* CONFIG_DEBUG_PAGEALLOC */

include/linux/mm_types.h

+0 −4
Original line number Diff line number Diff line
@@ -10,7 +10,6 @@ 
#include <linux/rwsem.h>

#include <linux/completion.h>

#include <linux/cpumask.h>

#include <linux/page-debug-flags.h>

#include <linux/uprobes.h>

#include <linux/page-flags-layout.h>

#include <asm/page.h>
@@ -186,9 +185,6 @@ struct page { 
	void *virtual;			/* Kernel virtual address (NULL if

					   not kmapped, ie. highmem) */

#endif /* WANT_PAGE_VIRTUAL */

#ifdef CONFIG_WANT_PAGE_DEBUG_FLAGS

	unsigned long debug_flags;	/* Use atomic bitops on this */

#endif



#ifdef CONFIG_KMEMCHECK

	/*

include/linux/page-debug-flags.h

deleted100644 → 0
+0 −32
Original line number Diff line number Diff line 
#ifndef LINUX_PAGE_DEBUG_FLAGS_H

#define  LINUX_PAGE_DEBUG_FLAGS_H



/*

 * page->debug_flags bits:

 *

 * PAGE_DEBUG_FLAG_POISON is set for poisoned pages. This is used to

 * implement generic debug pagealloc feature. The pages are filled with

 * poison patterns and set this flag after free_pages(). The poisoned

 * pages are verified whether the patterns are not corrupted and clear

 * the flag before alloc_pages().

 */



enum page_debug_flags {

	PAGE_DEBUG_FLAG_POISON,		/* Page is poisoned */

	PAGE_DEBUG_FLAG_GUARD,

};



/*

 * Ensure that CONFIG_WANT_PAGE_DEBUG_FLAGS reliably

 * gets turned off when no debug features are enabling it!

 */



#ifdef CONFIG_WANT_PAGE_DEBUG_FLAGS

#if !defined(CONFIG_PAGE_POISONING) && \

    !defined(CONFIG_PAGE_GUARD) \

/* && !defined(CONFIG_PAGE_DEBUG_SOMETHING_ELSE) && ... */

#error WANT_PAGE_DEBUG_FLAGS is turned on with no debug features!

#endif

#endif /* CONFIG_WANT_PAGE_DEBUG_FLAGS */



#endif /* LINUX_PAGE_DEBUG_FLAGS_H */

include/linux/page_ext.h

+15 −0
Original line number Diff line number Diff line
@@ -9,6 +9,21 @@ struct page_ext_operations { 


#ifdef CONFIG_PAGE_EXTENSION



/*

 * page_ext->flags bits:

 *

 * PAGE_EXT_DEBUG_POISON is set for poisoned pages. This is used to

 * implement generic debug pagealloc feature. The pages are filled with

 * poison patterns and set this flag after free_pages(). The poisoned

 * pages are verified whether the patterns are not corrupted and clear

 * the flag before alloc_pages().

 */



enum page_ext_flags {

	PAGE_EXT_DEBUG_POISON,		/* Page is poisoned */

	PAGE_EXT_DEBUG_GUARD,

};



/*

 * Page Extension can be considered as an extended mem_map.

 * A page_ext page is associated with every page descriptor. The

mm/Kconfig.debug

+1 −0
Original line number Diff line number Diff line
@@ -12,6 +12,7 @@ config DEBUG_PAGEALLOC 
	depends on DEBUG_KERNEL

	depends on !HIBERNATION || ARCH_SUPPORTS_DEBUG_PAGEALLOC && !PPC && !SPARC

	depends on !KMEMCHECK

	select PAGE_EXTENSION

	select PAGE_POISONING if !ARCH_SUPPORTS_DEBUG_PAGEALLOC

	select PAGE_GUARD if ARCH_SUPPORTS_DEBUG_PAGEALLOC

	---help---

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