+ mm-distinguish-vmalloc-pages.patch added to -mm tree

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The patch titled
     Subject: mm: distinguish VMalloc pages
has been added to the -mm tree.  Its filename is
     mm-distinguish-vmalloc-pages.patch

This patch should soon appear at
    http://ozlabs.org/~akpm/mmots/broken-out/mm-distinguish-vmalloc-pages.patch
and later at
    http://ozlabs.org/~akpm/mmotm/broken-out/mm-distinguish-vmalloc-pages.patch

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*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***

The -mm tree is included into linux-next and is updated
there every 3-4 working days

------------------------------------------------------
From: Matthew Wilcox <mawilcox@xxxxxxxxxxxxx>
Subject: mm: distinguish VMalloc pages

For diagnosing various performance and memory-leak problems, it is helpful
to be able to distinguish pages which are in use as VMalloc pages. 
Unfortunately, we cannot use the page_type field in struct page, as this
is in use for mapcount by some drivers which map vmalloced pages to
userspace.

Use a special page->mapping value to distinguish VMalloc pages from other
kinds of pages.  Also record a pointer to the vm_struct and the offset
within the area in struct page to help reconstruct exactly what this page
is being used for.

Link: http://lkml.kernel.org/r/20180518194519.3820-18-willy@xxxxxxxxxxxxx
Signed-off-by: Matthew Wilcox <mawilcox@xxxxxxxxxxxxx>
Cc: Christoph Lameter <cl@xxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Cc: Jérôme Glisse <jglisse@xxxxxxxxxx>
Cc: "Kirill A . Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Lai Jiangshan <jiangshanlai@xxxxxxxxx>
Cc: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
Cc: Pekka Enberg <penberg@xxxxxxxxxx>
Cc: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---

 fs/proc/page.c                         |    2 +
 include/linux/mm_types.h               |    5 ++++
 include/linux/page-flags.h             |   25 +++++++++++++++++++++++
 include/uapi/linux/kernel-page-flags.h |    1 
 mm/vmalloc.c                           |    5 +++-
 tools/vm/page-types.c                  |    1 
 6 files changed, 38 insertions(+), 1 deletion(-)

diff -puN fs/proc/page.c~mm-distinguish-vmalloc-pages fs/proc/page.c
--- a/fs/proc/page.c~mm-distinguish-vmalloc-pages
+++ a/fs/proc/page.c
@@ -156,6 +156,8 @@ u64 stable_page_flags(struct page *page)
 		u |= 1 << KPF_BALLOON;
 	if (PageTable(page))
 		u |= 1 << KPF_PGTABLE;
+	if (PageVMalloc(page))
+		u |= 1 << KPF_VMALLOC;
 
 	if (page_is_idle(page))
 		u |= 1 << KPF_IDLE;
diff -puN include/linux/mm_types.h~mm-distinguish-vmalloc-pages include/linux/mm_types.h
--- a/include/linux/mm_types.h~mm-distinguish-vmalloc-pages
+++ a/include/linux/mm_types.h
@@ -146,6 +146,11 @@ struct page {
 			spinlock_t ptl;
 #endif
 		};
+		struct {	/* VMalloc pages */
+			struct vm_struct *vm_area;
+			unsigned long vm_offset;
+			unsigned long _vm_id;	/* MAPPING_VMalloc */
+		};
 		struct {	/* ZONE_DEVICE pages */
 			/** @pgmap: Points to the hosting device page map. */
 			struct dev_pagemap *pgmap;
diff -puN include/linux/page-flags.h~mm-distinguish-vmalloc-pages include/linux/page-flags.h
--- a/include/linux/page-flags.h~mm-distinguish-vmalloc-pages
+++ a/include/linux/page-flags.h
@@ -699,6 +699,31 @@ PAGE_TYPE_OPS(Kmemcg, kmemcg)
  */
 PAGE_TYPE_OPS(Table, table)
 
+/*
+ * vmalloc pages may be mapped to userspace, so we need some other way
+ * to distinguish them from other kinds of pages.  Use page->mapping
+ * for this purpose.  Values below 0x1000 cannot be real pointers.
+ */
+#define MAPPING_VMalloc		(void *)0x440
+
+#define PAGE_MAPPING_OPS(name)						\
+static __always_inline int Page##name(struct page *page)		\
+{									\
+	return page->mapping == MAPPING_##name;				\
+}									\
+static __always_inline void __SetPage##name(struct page *page)		\
+{									\
+	VM_BUG_ON_PAGE(page->mapping != NULL, page);			\
+	page->mapping = MAPPING_##name;					\
+}									\
+static __always_inline void __ClearPage##name(struct page *page)	\
+{									\
+	VM_BUG_ON_PAGE(page->mapping != MAPPING_##name, page);		\
+	page->mapping = NULL;						\
+}
+
+PAGE_MAPPING_OPS(VMalloc)
+
 extern bool is_free_buddy_page(struct page *page);
 
 __PAGEFLAG(Isolated, isolated, PF_ANY);
diff -puN include/uapi/linux/kernel-page-flags.h~mm-distinguish-vmalloc-pages include/uapi/linux/kernel-page-flags.h
--- a/include/uapi/linux/kernel-page-flags.h~mm-distinguish-vmalloc-pages
+++ a/include/uapi/linux/kernel-page-flags.h
@@ -36,5 +36,6 @@
 #define KPF_ZERO_PAGE		24
 #define KPF_IDLE		25
 #define KPF_PGTABLE		26
+#define KPF_VMALLOC		27
 
 #endif /* _UAPILINUX_KERNEL_PAGE_FLAGS_H */
diff -puN mm/vmalloc.c~mm-distinguish-vmalloc-pages mm/vmalloc.c
--- a/mm/vmalloc.c~mm-distinguish-vmalloc-pages
+++ a/mm/vmalloc.c
@@ -1522,7 +1522,7 @@ static void __vunmap(const void *addr, i
 		for (i = 0; i < area->nr_pages; i++) {
 			struct page *page = area->pages[i];
 
-			BUG_ON(!page);
+			__ClearPageVMalloc(page);
 			__free_pages(page, 0);
 		}
 
@@ -1692,6 +1692,9 @@ static void *__vmalloc_area_node(struct
 			area->nr_pages = i;
 			goto fail;
 		}
+		__SetPageVMalloc(page);
+		page->vm_area = area;
+		page->vm_offset = i;
 		area->pages[i] = page;
 		if (gfpflags_allow_blocking(gfp_mask|highmem_mask))
 			cond_resched();
diff -puN tools/vm/page-types.c~mm-distinguish-vmalloc-pages tools/vm/page-types.c
--- a/tools/vm/page-types.c~mm-distinguish-vmalloc-pages
+++ a/tools/vm/page-types.c
@@ -132,6 +132,7 @@ static const char * const page_flag_name
 	[KPF_THP]		= "t:thp",
 	[KPF_BALLOON]		= "o:balloon",
 	[KPF_PGTABLE]		= "g:pgtable",
+	[KPF_VMALLOC]		= "V:vmalloc",
 	[KPF_ZERO_PAGE]		= "z:zero_page",
 	[KPF_IDLE]              = "i:idle_page",
 
_

Patches currently in -mm which might be from mawilcox@xxxxxxxxxxxxx are

lib-test_bitmapc-fix-bitmap-optimisation-tests-to-report-errors-correctly.patch
slab-__gfp_zero-is-incompatible-with-a-constructor.patch
s390-use-_refcount-for-pgtables.patch
mm-split-page_type-out-from-_mapcount.patch
mm-mark-pages-in-use-for-page-tables.patch
mm-switch-s_mem-and-slab_cache-in-struct-page.patch
mm-move-private-union-within-struct-page.patch
mm-move-_refcount-out-of-struct-page-union.patch
mm-combine-first-three-unions-in-struct-page.patch
mm-use-page-deferred_list.patch
mm-move-lru-union-within-struct-page.patch
mm-combine-lru-and-main-union-in-struct-page.patch
mm-improve-struct-page-documentation.patch
mm-add-pt_mm-to-struct-page.patch
mm-add-hmm_data-to-struct-page.patch
slabslub-remove-rcu_head-size-checks.patch
slub-remove-kmem_cache-reserved.patch
slub-remove-reserved-file-from-sysfs.patch
mm-distinguish-vmalloc-pages.patch
ida-remove-simple_ida_lock.patch

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