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Subject[PATCH v5 3/4] mm: Mark pages allocated through vmalloc
Date
From: Matthew Wilcox <mawilcox@microsoft.com>

Use a bit in page_type to mark pages which have been allocated through
vmalloc. 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.

Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
---
fs/proc/page.c | 2 ++
include/linux/page-flags.h | 6 ++++++
include/uapi/linux/kernel-page-flags.h | 2 +-
mm/vmalloc.c | 2 ++
tools/vm/page-types.c | 1 +
5 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/fs/proc/page.c b/fs/proc/page.c
index 1491918a33c3..c9757af919a3 100644
--- a/fs/proc/page.c
+++ b/fs/proc/page.c
@@ -154,6 +154,8 @@ u64 stable_page_flags(struct page *page)

if (PageBalloon(page))
u |= 1 << KPF_BALLOON;
+ if (PageVmalloc(page))
+ u |= 1 << KPF_VMALLOC;

if (page_is_idle(page))
u |= 1 << KPF_IDLE;
diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
index be3cd45efeb6..1503d314bb3d 100644
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -643,6 +643,7 @@ PAGEFLAG_FALSE(DoubleMap)
#define PG_buddy 0x00000080
#define PG_balloon 0x00000100
#define PG_kmemcg 0x00000200
+#define PG_vmalloc 0x00000400

#define PageType(page, flag) \
((page->page_type & (PAGE_TYPE_BASE | flag)) == PAGE_TYPE_BASE)
@@ -681,6 +682,11 @@ PAGE_TYPE_OPS(Balloon, balloon)
*/
PAGE_TYPE_OPS(Kmemcg, kmemcg)

+/*
+ * Pages allocated through vmalloc are tagged with this bit.
+ */
+PAGE_TYPE_OPS(Vmalloc, vmalloc)
+
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 fa139841ec18..5f1735ff05b3 100644
--- a/include/uapi/linux/kernel-page-flags.h
+++ b/include/uapi/linux/kernel-page-flags.h
@@ -35,6 +35,6 @@
#define KPF_BALLOON 23
#define KPF_ZERO_PAGE 24
#define KPF_IDLE 25
-
+#define KPF_VMALLOC 26

#endif /* _UAPILINUX_KERNEL_PAGE_FLAGS_H */
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index ebff729cc956..3bc0538fc21b 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -1536,6 +1536,7 @@ static void __vunmap(const void *addr, int deallocate_pages)
struct page *page = area->pages[i];

BUG_ON(!page);
+ __ClearPageVmalloc(page);
__free_pages(page, 0);
}

@@ -1705,6 +1706,7 @@ static void *__vmalloc_area_node(struct vm_struct *area, gfp_t gfp_mask,
area->nr_pages = i;
goto fail;
}
+ __SetPageVmalloc(page);
area->pages[i] = page;
if (gfpflags_allow_blocking(gfp_mask|highmem_mask))
cond_resched();
diff --git a/tools/vm/page-types.c b/tools/vm/page-types.c
index a8783f48f77f..116f59eff5e2 100644
--- a/tools/vm/page-types.c
+++ b/tools/vm/page-types.c
@@ -131,6 +131,7 @@ static const char * const page_flag_names[] = {
[KPF_KSM] = "x:ksm",
[KPF_THP] = "t:thp",
[KPF_BALLOON] = "o:balloon",
+ [KPF_VMALLOC] = "V:vmalloc",
[KPF_ZERO_PAGE] = "z:zero_page",
[KPF_IDLE] = "i:idle_page",

--
2.16.1
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