@@ -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;
@@ -141,6 +141,11 @@ struct page {
spinlock_t ptl;
#endif
};
+ struct { /* VMalloc pages */
+ struct vm_struct *vm_area;
+ unsigned long vm_offset;
+ unsigned long _vm_id; /* MAPPING_VMalloc */
+ };
/** @rcu_head: You can use this to free a page by RCU. */
struct rcu_head rcu_head;
@@ -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);
@@ -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 */
@@ -1535,7 +1535,7 @@ static void __vunmap(const void *addr, int deallocate_pages)
for (i = 0; i < area->nr_pages; i++) {
struct page *page = area->pages[i];
- BUG_ON(!page);
+ __ClearPageVMalloc(page);
__free_pages(page, 0);
}
@@ -1704,6 +1704,9 @@ static void *__vmalloc_area_node(struct vm_struct *area, gfp_t gfp_mask,
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))
cond_resched();
@@ -132,6 +132,7 @@ static const char * const page_flag_names[] = {
[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",
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. Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com> --- This patch would be a superset of Igor's patch to add an ->area field to struct page. It's on top of my recent series to rearrange struct page. I think it's a nice demonstration of how you don't have to go hunting around for fields that may or may not be in use; you just add your own little struct to the union, and you're done. As well as being *really* useful for debugging, of course! 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(-)