Commit 1d40a5ea authored by Matthew Wilcox's avatar Matthew Wilcox Committed by Linus Torvalds
Browse files

mm: mark pages in use for page tables 

Define a new PageTable bit in the page_type and use it to mark pages in
use as page tables.  This can be helpful when debugging crashdumps or
analysing memory fragmentation.  Add a KPF flag to report these pages to
userspace and update page-types.c to interpret that flag.

Note that only pages currently accounted as NR_PAGETABLES are tracked as
PageTable; this does not include pgd/p4d/pud/pmd pages.  Those will be the
subject of a later patch.

Link: http://lkml.kernel.org/r/20180518194519.3820-4-willy@infradead.org


Signed-off-by: default avatarMatthew Wilcox <mawilcox@microsoft.com>
Acked-by: default avatarKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: default avatarVlastimil Babka <vbabka@suse.cz>
Cc: Christoph Lameter <cl@linux.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Jérôme Glisse <jglisse@redhat.com>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 6e292b9b

fs/proc/page.c

+2 −0
Original line number Diff line number Diff line
@@ -154,6 +154,8 @@ u64 stable_page_flags(struct page *page) 


	if (PageBalloon(page))

		u |= 1 << KPF_BALLOON;

	if (PageTable(page))

		u |= 1 << KPF_PGTABLE;



	if (page_is_idle(page))

		u |= 1 << KPF_IDLE;

include/linux/mm.h

+2 −0
Original line number Diff line number Diff line
@@ -1851,6 +1851,7 @@ static inline bool pgtable_page_ctor(struct page *page) 
{

	if (!ptlock_init(page))

		return false;

	__SetPageTable(page);

	inc_zone_page_state(page, NR_PAGETABLE);

	return true;

}
@@ -1858,6 +1859,7 @@ static inline bool pgtable_page_ctor(struct page *page) 
static inline void pgtable_page_dtor(struct page *page)

{

	pte_lock_deinit(page);

	__ClearPageTable(page);

	dec_zone_page_state(page, NR_PAGETABLE);

}

include/linux/page-flags.h

+6 −0
Original line number Diff line number Diff line
@@ -655,6 +655,7 @@ PAGEFLAG_FALSE(DoubleMap) 
#define PG_buddy	0x00000080

#define PG_balloon	0x00000100

#define PG_kmemcg	0x00000200

#define PG_table	0x00000400



#define PageType(page, flag)						\

	((page->page_type & (PAGE_TYPE_BASE | flag)) == PAGE_TYPE_BASE)
@@ -693,6 +694,11 @@ PAGE_TYPE_OPS(Balloon, balloon) 
 */

PAGE_TYPE_OPS(Kmemcg, kmemcg)



/*

 * Marks pages in use as page tables.

 */

PAGE_TYPE_OPS(Table, table)



extern bool is_free_buddy_page(struct page *page);



__PAGEFLAG(Isolated, isolated, PF_ANY);

include/uapi/linux/kernel-page-flags.h

+1 −1
Original line number Diff line number Diff line
@@ -35,6 +35,6 @@ 
#define KPF_BALLOON		23

#define KPF_ZERO_PAGE		24

#define KPF_IDLE		25



#define KPF_PGTABLE		26



#endif /* _UAPILINUX_KERNEL_PAGE_FLAGS_H */

tools/vm/page-types.c

+1 −0
Original line number Diff line number Diff line
@@ -131,6 +131,7 @@ static const char * const page_flag_names[] = { 
	[KPF_KSM]		= "x:ksm",

	[KPF_THP]		= "t:thp",

	[KPF_BALLOON]		= "o:balloon",

	[KPF_PGTABLE]		= "g:pgtable",

	[KPF_ZERO_PAGE]		= "z:zero_page",

	[KPF_IDLE]              = "i:idle_page",

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