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mm, page_owner: track and print last migrate reason

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During migration, page_owner info is now copied with the rest of the
page, so the stacktrace leading to free page allocation during migration
is overwritten.  For debugging purposes, it might be however useful to
know that the page has been migrated since its initial allocation.  This
might happen many times during the lifetime for different reasons and
fully tracking this, especially with stacktraces would incur extra
memory costs.  As a compromise, store and print the migrate_reason of
the last migration that occurred to the page.  This is enough to
distinguish compaction, numa balancing etc.

Example page_owner entry after the patch:

  Page allocated via order 0, mask 0x24200ca(GFP_HIGHUSER_MOVABLE)
  PFN 628753 type Movable Block 1228 type Movable Flags 0x1fffff80040030(dirty|lru|swapbacked)
   [<ffffffff811682c4>] __alloc_pages_nodemask+0x134/0x230
   [<ffffffff811b6325>] alloc_pages_vma+0xb5/0x250
   [<ffffffff81177491>] shmem_alloc_page+0x61/0x90
   [<ffffffff8117a438>] shmem_getpage_gfp+0x678/0x960
   [<ffffffff8117c2b9>] shmem_fallocate+0x329/0x440
   [<ffffffff811de600>] vfs_fallocate+0x140/0x230
   [<ffffffff811df434>] SyS_fallocate+0x44/0x70
   [<ffffffff8158cc2e>] entry_SYSCALL_64_fastpath+0x12/0x71
  Page has been migrated, last migrate reason: compaction

Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Vlastimil Babka 2016-03-15 14:56:18 -07:00 committed by Linus Torvalds
parent d435edca92
commit 7cd12b4abf
6 changed files with 50 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
include/linux/migrate.h
View File

@ -23,9 +23,13 @@ enum migrate_reason {
MR_SYSCALL, /* also applies to cpusets */
MR_MEMPOLICY_MBIND,
MR_NUMA_MISPLACED,
MR_CMA
MR_CMA,
MR_TYPES
};
/* In mm/debug.c; also keep sync with include/trace/events/migrate.h */
extern char *migrate_reason_names[MR_TYPES];
#ifdef CONFIG_MIGRATION
extern void putback_movable_pages(struct list_head *l);

1
include/linux/page_ext.h
View File

@ -45,6 +45,7 @@ struct page_ext {
unsigned int order;
gfp_t gfp_mask;
unsigned int nr_entries;
int last_migrate_reason;
unsigned long trace_entries[8];
#endif
};

9
include/linux/page_owner.h
View File

@ -12,6 +12,7 @@ extern void __set_page_owner(struct page *page,
unsigned int order, gfp_t gfp_mask);
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);
static inline void reset_page_owner(struct page *page, unsigned int order)
{
@ -38,6 +39,11 @@ static inline void copy_page_owner(struct page *oldpage, struct page *newpage)
if (static_branch_unlikely(&page_owner_inited))
__copy_page_owner(oldpage, newpage);
}
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);
}
#else
static inline void reset_page_owner(struct page *page, unsigned int order)
{
@ -53,5 +59,8 @@ static inline gfp_t get_page_owner_gfp(struct page *page)
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)
{
}
#endif /* CONFIG_PAGE_OWNER */
#endif /* __LINUX_PAGE_OWNER_H */

11
mm/debug.c
View File

@ -10,9 +10,20 @@
#include <linux/trace_events.h>
#include <linux/memcontrol.h>
#include <trace/events/mmflags.h>
#include <linux/migrate.h>
#include "internal.h"
char *migrate_reason_names[MR_TYPES] = {
"compaction",
"memory_failure",
"memory_hotplug",
"syscall_or_cpuset",
"mempolicy_mbind",
"numa_misplaced",
"cma",
};
const struct trace_print_flags pageflag_names[] = {
__def_pageflag_names,
{0, NULL}

10
mm/migrate.c
View File

@ -955,8 +955,10 @@ static ICE_noinline int unmap_and_move(new_page_t get_new_page,
}
rc = __unmap_and_move(page, newpage, force, mode);
if (rc == MIGRATEPAGE_SUCCESS)
if (rc == MIGRATEPAGE_SUCCESS) {
put_new_page = NULL;
set_page_owner_migrate_reason(newpage, reason);
}
out:
if (rc != -EAGAIN) {
@ -1021,7 +1023,7 @@ out:
static int unmap_and_move_huge_page(new_page_t get_new_page,
free_page_t put_new_page, unsigned long private,
struct page *hpage, int force,
enum migrate_mode mode)
enum migrate_mode mode, int reason)
{
int rc = -EAGAIN;
int *result = NULL;
@ -1079,6 +1081,7 @@ put_anon:
if (rc == MIGRATEPAGE_SUCCESS) {
hugetlb_cgroup_migrate(hpage, new_hpage);
put_new_page = NULL;
set_page_owner_migrate_reason(new_hpage, reason);
}
unlock_page(hpage);
@ -1151,7 +1154,7 @@ int migrate_pages(struct list_head *from, new_page_t get_new_page,
if (PageHuge(page))
rc = unmap_and_move_huge_page(get_new_page,
put_new_page, private, page,
pass > 2, mode);
pass > 2, mode, reason);
else
rc = unmap_and_move(get_new_page, put_new_page,
private, page, pass > 2, mode,
@ -1842,6 +1845,7 @@ fail_putback:
set_page_memcg(new_page, page_memcg(page));
set_page_memcg(page, NULL);
page_remove_rmap(page, true);
set_page_owner_migrate_reason(new_page, MR_NUMA_MISPLACED);
spin_unlock(ptl);
mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);

17
mm/page_owner.c
View File

@ -6,6 +6,7 @@
#include <linux/stacktrace.h>
#include <linux/page_owner.h>
#include <linux/jump_label.h>
#include <linux/migrate.h>
#include "internal.h"
static bool page_owner_disabled = true;
@ -73,10 +74,18 @@ void __set_page_owner(struct page *page, unsigned int order, gfp_t gfp_mask)
page_ext->order = order;
page_ext->gfp_mask = gfp_mask;
page_ext->nr_entries = trace.nr_entries;
page_ext->last_migrate_reason = -1;
__set_bit(PAGE_EXT_OWNER, &page_ext->flags);
}
void __set_page_owner_migrate_reason(struct page *page, int reason)
{
struct page_ext *page_ext = lookup_page_ext(page);
page_ext->last_migrate_reason = reason;
}
gfp_t __get_page_owner_gfp(struct page *page)
{
struct page_ext *page_ext = lookup_page_ext(page);
@ -151,6 +160,14 @@ print_page_owner(char __user *buf, size_t count, unsigned long pfn,
if (ret >= count)
goto err;
if (page_ext->last_migrate_reason != -1) {
ret += snprintf(kbuf + ret, count - ret,
"Page has been migrated, last migrate reason: %s\n",
migrate_reason_names[page_ext->last_migrate_reason]);
if (ret >= count)
goto err;
}
ret += snprintf(kbuf + ret, count - ret, "\n");
if (ret >= count)
goto err;