From: Matthew Wilcox <mawil...@microsoft.com>
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.
Signed-off-by: Matthew Wilcox <mawil...@microsoft.com>
Acked-by: Kirill A. Shutemov <kirill.shute...@linux.intel.com>
---
arch/tile/mm/pgtable.c | 3 +++
fs/proc/page.c | 2 ++
include/linux/mm.h | 2 ++
include/linux/page-flags.h | 6 ++++++
include/uapi/linux/kernel-page-flags.h | 1 +
tools/vm/page-types.c | 1 +
6 files changed, 15 insertions(+)
diff --git a/arch/tile/mm/pgtable.c b/arch/tile/mm/pgtable.c
index ec5576fd3a86..6dff12db335d 100644
--- a/arch/tile/mm/pgtable.c
+++ b/arch/tile/mm/pgtable.c
@@ -206,6 +206,7 @@ struct page *pgtable_alloc_one(struct mm_struct *mm,
unsigned long address,
*/
for (i = 1; i < order; ++i) {
init_page_count(p+i);
+ __SetPageTable(p+i);
inc_zone_page_state(p+i, NR_PAGETABLE);
}
@@ -226,6 +227,7 @@ void pgtable_free(struct mm_struct *mm, struct page *p, int
order)
for (i = 1; i < order; ++i) {
__free_page(p+i);
+ __ClearPageTable(p+i);
dec_zone_page_state(p+i, NR_PAGETABLE);
}
}
@@ -240,6 +242,7 @@ void __pgtable_free_tlb(struct mmu_gather *tlb, struct page
*pte,
for (i = 1; i < order; ++i) {
tlb_remove_page(tlb, pte + i);
+ __ClearPageTable(pte + i);
dec_zone_page_state(pte + i, NR_PAGETABLE);
}
}
diff --git a/fs/proc/page.c b/fs/proc/page.c
index c9757af919a3..80275e7a963b 100644
--- a/fs/proc/page.c
+++ b/fs/proc/page.c
@@ -156,6 +156,8 @@ u64 stable_page_flags(struct page *page)
u |= 1 << KPF_BALLOON;
if (PageVmalloc(page))
u |= 1 << KPF_VMALLOC;
+ if (PageTable(page))
+ u |= 1 << KPF_PGTABLE;
if (page_is_idle(page))
u |= 1 << KPF_IDLE;
diff --git a/include/linux/mm.h b/include/linux/mm.h
index ad06d42adb1a..7a15042d6828 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1829,6 +1829,7 @@ 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;
}
@@ -1836,6 +1837,7 @@ 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);
}
diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
index 1503d314bb3d..aa5c8c1c6d38 100644
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -644,6 +644,7 @@ PAGEFLAG_FALSE(DoubleMap)
#define PG_balloon 0x00000100
#define PG_kmemcg 0x00000200
#define PG_vmalloc 0x00000400
+#define PG_table 0x00000800
#define PageType(page, flag) \
((page->page_type & (PAGE_TYPE_BASE | flag)) == PAGE_TYPE_BASE)
@@ -687,6 +688,11 @@ PAGE_TYPE_OPS(Kmemcg, kmemcg)
*/
PAGE_TYPE_OPS(Vmalloc, vmalloc)
+/*
+ * 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);
diff --git a/include/uapi/linux/kernel-page-flags.h
b/include/uapi/linux/kernel-page-flags.h
index 5f1735ff05b3..3c51d8bf8b7b 100644
--- a/include/uapi/linux/kernel-page-flags.h
+++ b/include/uapi/linux/kernel-page-flags.h
@@ -36,5 +36,6 @@
#define KPF_ZERO_PAGE 24
#define KPF_IDLE 25
#define KPF_VMALLOC 26
+#define KPF_PGTABLE 27
#endif /* _UAPILINUX_KERNEL_PAGE_FLAGS_H */
diff --git a/tools/vm/page-types.c b/tools/vm/page-types.c
index 116f59eff5e2..bbb992694f05 100644
--- a/tools/vm/page-types.c
+++ b/tools/vm/page-types.c
@@ -132,6 +132,7 @@ static const char * const page_flag_names[] = {
[KPF_THP] = "t:thp",
[KPF_BALLOON] = "o:balloon",
[KPF_VMALLOC] = "V:vmalloc",
+ [KPF_PGTABLE] = "g:pgtable",
[KPF_ZERO_PAGE] = "z:zero_page",
[KPF_IDLE] = "i:idle_page",
--
2.16.1
