The page_owner mechanism is useful for dealing with memory leaks. By reading
/sys/kernel/debug/page_owner one can determine the stack traces leading to
allocations of all pages, and find e.g. a buggy driver.
This information might be also potentially useful for debugging, such as the
VM_BUG_ON_PAGE() calls to dump_page(). So let's print the stored info from
dump_page().
Example output:
page:ffffea0002868a00 count:1 mapcount:0 mapping:ffff8800bba8e958 index:0x63a22c
flags: 0x1fffff80000060(lru|active)
page dumped because: VM_BUG_ON_PAGE(1)
page->mem_cgroup:ffff880138efdc00
page allocated via order 0, migratetype Movable, gfp_mask 0x2420848(GFP_NOFS|GFP_NOFAIL|GFP_HARDWALL|GFP_MOVABLE)
[<ffffffff81164e8a>] __alloc_pages_nodemask+0x15a/0xa30
[<ffffffff811ab808>] alloc_pages_current+0x88/0x120
[<ffffffff8115bc36>] __page_cache_alloc+0xe6/0x120
[<ffffffff8115c226>] pagecache_get_page+0x56/0x200
[<ffffffff812058c2>] __getblk_slow+0xd2/0x2b0
[<ffffffff81205ae0>] __getblk_gfp+0x40/0x50
[<ffffffffa0283abe>] jbd2_journal_get_descriptor_buffer+0x3e/0x90 [jbd2]
[<ffffffffa027c793>] jbd2_journal_commit_transaction+0x8e3/0x1870 [jbd2]
page has been migrated, last migrate reason: compaction
Signed-off-by: Vlastimil Babka <vbabka@xxxxxxx>
Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
Cc: Minchan Kim <minchan@xxxxxxxxxx>
Cc: Sasha Levin <sasha.levin@xxxxxxxxxx>
Cc: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxx>
Acked-by: Michal Hocko <mhocko@xxxxxxxx>
---
include/linux/page_owner.h | 9 +++++++++
mm/debug.c | 2 ++
mm/page_alloc.c | 1 +
mm/page_owner.c | 25 +++++++++++++++++++++++++
4 files changed, 37 insertions(+)
diff --git a/include/linux/page_owner.h b/include/linux/page_owner.h
index 555893bf13d7..46f1b939948c 100644
--- a/include/linux/page_owner.h
+++ b/include/linux/page_owner.h
@@ -13,6 +13,7 @@ extern void __set_page_owner(struct page *page,
extern gfp_t __get_page_owner_gfp(struct page *page);
extern void __copy_page_owner(struct page *oldpage, struct page *newpage);
extern void __set_page_owner_migrate_reason(struct page *page, int reason);
+extern void __dump_page_owner(struct page *page);
static inline void reset_page_owner(struct page *page, unsigned int order)
{
@@ -44,6 +45,11 @@ static inline void set_page_owner_migrate_reason(struct page *page, int reason)
if (static_branch_unlikely(&page_owner_inited))
__set_page_owner_migrate_reason(page, reason);
}
+static inline void dump_page_owner(struct page *page)
+{
+ if (static_branch_unlikely(&page_owner_inited))
+ __dump_page_owner(page);
+}
#else
static inline void reset_page_owner(struct page *page, unsigned int order)
{
@@ -62,5 +68,8 @@ static inline void copy_page_owner(struct page *oldpage, struct page *newpage)
static inline void set_page_owner_migrate_reason(struct page *page, int reason)
{
}
+static inline void dump_page_owner(struct page *page)
+{
+}
#endif /* CONFIG_PAGE_OWNER */
#endif /* __LINUX_PAGE_OWNER_H */
diff --git a/mm/debug.c b/mm/debug.c
index f13778ae84a2..7260644d8cc1 100644
--- a/mm/debug.c
+++ b/mm/debug.c
@@ -11,6 +11,7 @@
#include <linux/memcontrol.h>
#include <trace/events/mmflags.h>
#include <linux/migrate.h>
+#include <linux/page_owner.h>
#include "internal.h"
@@ -67,6 +68,7 @@ void dump_page_badflags(struct page *page, const char *reason,
void dump_page(struct page *page, const char *reason)
{
dump_page_badflags(page, reason, 0);
+ dump_page_owner(page);
}
EXPORT_SYMBOL(dump_page);
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 67538b58e478..7718ee40726a 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -441,6 +441,7 @@ static void bad_page(struct page *page, const char *reason,
printk(KERN_ALERT "BUG: Bad page state in process %s pfn:%05lx\n",
current->comm, page_to_pfn(page));
dump_page_badflags(page, reason, bad_flags);
+ dump_page_owner(page);
print_modules();
dump_stack();
diff --git a/mm/page_owner.c b/mm/page_owner.c
index 58ce2816e2c2..011377548b4f 100644
--- a/mm/page_owner.c
+++ b/mm/page_owner.c
@@ -183,6 +183,31 @@ print_page_owner(char __user *buf, size_t count, unsigned long pfn,
return -ENOMEM;
}
+void __dump_page_owner(struct page *page)
+{
+ struct page_ext *page_ext = lookup_page_ext(page);
+ struct stack_trace trace = {
+ .nr_entries = page_ext->nr_entries,
+ .entries = &page_ext->trace_entries[0],
+ };
+ gfp_t gfp_mask = page_ext->gfp_mask;
+ int mt = gfpflags_to_migratetype(gfp_mask);
+
+ if (!test_bit(PAGE_EXT_OWNER, &page_ext->flags)) {
+ pr_alert("page_owner info is not active (free page?)\n");
+ return;
+ }
+
+ pr_alert("page allocated via order %u, migratetype %s, "
+ "gfp_mask %#x(%pgg)\n", page_ext->order,
+ migratetype_names[mt], gfp_mask, &gfp_mask);
+ print_stack_trace(&trace, 0);
+
+ if (page_ext->last_migrate_reason != -1)
+ pr_alert("page has been migrated, last migrate reason: %s\n",
+ migrate_reason_names[page_ext->last_migrate_reason]);
+}
+
static ssize_t
read_page_owner(struct file *file, char __user *buf, size_t count, loff_t *ppos)
{
--
2.6.3
--
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