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mm: mark pages in use for page tables

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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: Matthew Wilcox <mawilcox@microsoft.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Vlastimil 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: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Matthew Wilcox 2018-06-07 17:08:23 -07:00 committed by Linus Torvalds
parent 6e292b9be7
commit 1d40a5ea01
5 changed files with 12 additions and 1 deletions
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2
fs/proc/page.c
View File

@ -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;

2
include/linux/mm.h
View File

@ -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);
}

6
include/linux/page-flags.h
View File

@ -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);

2
include/uapi/linux/kernel-page-flags.h
View File

@ -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 */

1
tools/vm/page-types.c
View File

@ -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",