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mm/idle_page_tracking: make PG_idle reusable 

PG_idle and PG_young allow the two PTE Accessed bit users, Idle Page
Tracking and the reclaim logic concurrently work while not interfering
with each other.  That is, when they need to clear the Accessed bit, they
set PG_young to represent the previous state of the bit, respectively.
And when they need to read the bit, if the bit is cleared, they further
read the PG_young to know whether the other has cleared the bit meanwhile
or not.

For yet another user of the PTE Accessed bit, we could add another page
flag, or extend the mechanism to use the flags.  For the DAMON usecase,
however, we don't need to do that just yet.  IDLE_PAGE_TRACKING and DAMON
are mutually exclusive, so there's only ever going to be one user of the
current set of flags.

In this commit, we split out the CONFIG options to allow for the use of
PG_young and PG_idle outside of idle page tracking.

In the next commit, DAMON's reference implementation of the virtual memory
address space monitoring primitives will use it.

[sjpark@amazon.de: set PAGE_EXTENSION for non-64BIT]
  Link: https://lkml.kernel.org/r/20210806095153.6444-1-sj38.park@gmail.com
[akpm@linux-foundation.org: tweak Kconfig text]
[sjpark@amazon.de: hide PAGE_IDLE_FLAG from users]
  Link: https://lkml.kernel.org/r/20210813081238.34705-1-sj38.park@gmail.com

Link: https://lkml.kernel.org/r/20210716081449.22187-5-sj38.park@gmail.com
Signed-off-by: SeongJae Park <sjpark@amazon.de>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Reviewed-by: Fernand Sieber <sieberf@amazon.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Amit Shah <amit@kernel.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Brendan Higgins <brendanhiggins@google.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: David Woodhouse <dwmw@amazon.com>
Cc: Fan Du <fan.du@intel.com>
Cc: Greg Kroah-Hartman <greg@kroah.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Joe Perches <joe@perches.com>
Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Leonard Foerster <foersleo@amazon.de>
Cc: Marco Elver <elver@google.com>
Cc: Markus Boehme <markubo@amazon.de>
Cc: Maximilian Heyne <mheyne@amazon.de>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Steven Rostedt (VMware) <rostedt@goodmis.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
SeongJae Park 2021-09-07 19:56:40 -07:00 committed by Linus Torvalds
parent b9a6ac4e4e
commit 1c676e0d9b
7 changed files with 27 additions and 19 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
include/linux/page-flags.h
View File

@ -131,7 +131,7 @@ enum pageflags {
#ifdef CONFIG_MEMORY_FAILURE
PG_hwpoison, /* hardware poisoned page. Don't touch */
#endif
#if defined(CONFIG_IDLE_PAGE_TRACKING) && defined(CONFIG_64BIT)
#if defined(CONFIG_PAGE_IDLE_FLAG) && defined(CONFIG_64BIT)
PG_young,
PG_idle,
#endif
@ -441,7 +441,7 @@ PAGEFLAG_FALSE(HWPoison)
#define __PG_HWPOISON 0
#endif
#if defined(CONFIG_IDLE_PAGE_TRACKING) && defined(CONFIG_64BIT)
#if defined(CONFIG_PAGE_IDLE_FLAG) && defined(CONFIG_64BIT)
TESTPAGEFLAG(Young, young, PF_ANY)
SETPAGEFLAG(Young, young, PF_ANY)
TESTCLEARFLAG(Young, young, PF_ANY)

2
include/linux/page_ext.h
View File

@ -19,7 +19,7 @@ struct page_ext_operations {
enum page_ext_flags {
PAGE_EXT_OWNER,
PAGE_EXT_OWNER_ALLOCATED,
#if defined(CONFIG_IDLE_PAGE_TRACKING) && !defined(CONFIG_64BIT)
#if defined(CONFIG_PAGE_IDLE_FLAG) && !defined(CONFIG_64BIT)
PAGE_EXT_YOUNG,
PAGE_EXT_IDLE,
#endif

6
include/linux/page_idle.h
View File

@ -6,7 +6,7 @@
#include <linux/page-flags.h>
#include <linux/page_ext.h>
#ifdef CONFIG_IDLE_PAGE_TRACKING
#ifdef CONFIG_PAGE_IDLE_FLAG
#ifdef CONFIG_64BIT
static inline bool page_is_young(struct page *page)
@ -106,7 +106,7 @@ static inline void clear_page_idle(struct page *page)
}
#endif /* CONFIG_64BIT */
#else /* !CONFIG_IDLE_PAGE_TRACKING */
#else /* !CONFIG_PAGE_IDLE_FLAG */
static inline bool page_is_young(struct page *page)
{
@ -135,6 +135,6 @@ static inline void clear_page_idle(struct page *page)
{
}
#endif /* CONFIG_IDLE_PAGE_TRACKING */
#endif /* CONFIG_PAGE_IDLE_FLAG */
#endif /* _LINUX_MM_PAGE_IDLE_H */

2
include/trace/events/mmflags.h
View File

@ -75,7 +75,7 @@
#define IF_HAVE_PG_HWPOISON(flag,string)
#endif
#if defined(CONFIG_IDLE_PAGE_TRACKING) && defined(CONFIG_64BIT)
#if defined(CONFIG_PAGE_IDLE_FLAG) && defined(CONFIG_64BIT)
#define IF_HAVE_PG_IDLE(flag,string) ,{1UL << flag, string}
#else
#define IF_HAVE_PG_IDLE(flag,string)

10
mm/Kconfig
View File

@ -739,10 +739,18 @@ config DEFERRED_STRUCT_PAGE_INIT
lifetime of the system until these kthreads finish the
initialisation.
config PAGE_IDLE_FLAG
bool
select PAGE_EXTENSION if !64BIT
help
This adds PG_idle and PG_young flags to 'struct page'. PTE Accessed
bit writers can set the state of the bit in the flags so that PTE
Accessed bit readers may avoid disturbance.
config IDLE_PAGE_TRACKING
bool "Enable idle page tracking"
depends on SYSFS && MMU
select PAGE_EXTENSION if !64BIT
select PAGE_IDLE_FLAG
help
This feature allows to estimate the amount of user pages that have
not been touched during a given period of time. This information can

12
mm/page_ext.c
View File

@ -58,11 +58,21 @@
* can utilize this callback to initialize the state of it correctly.
*/
#if defined(CONFIG_PAGE_IDLE_FLAG) && !defined(CONFIG_64BIT)
static bool need_page_idle(void)
{
return true;
}
struct page_ext_operations page_idle_ops = {
.need = need_page_idle,
};
#endif
static struct page_ext_operations *page_ext_ops[] = {
#ifdef CONFIG_PAGE_OWNER
&page_owner_ops,
#endif
#if defined(CONFIG_IDLE_PAGE_TRACKING) && !defined(CONFIG_64BIT)
#if defined(CONFIG_PAGE_IDLE_FLAG) && !defined(CONFIG_64BIT)
&page_idle_ops,
#endif
};

10
mm/page_idle.c
View File

@ -207,16 +207,6 @@ static const struct attribute_group page_idle_attr_group = {
.name = "page_idle",
};
#ifndef CONFIG_64BIT
static bool need_page_idle(void)
{
return true;
}
struct page_ext_operations page_idle_ops = {
.need = need_page_idle,
};
#endif
static int __init page_idle_init(void)
{
int err;