From ca215086b14b89a0e70fc211314944aa6ce50020 Mon Sep 17 00:00:00 2001
From: David Hildenbrand <david@redhat.com>
Date: Tue, 5 Mar 2019 15:42:23 -0800
Subject: [PATCH] mm: convert PG_balloon to PG_offline
PG_balloon was introduced to implement page migration/compaction for
pages inflated in virtio-balloon. Nowadays, it is only a marker that a
page is part of virtio-balloon and therefore logically offline.
We also want to make use of this flag in other balloon drivers - for
inflated pages or when onlining a section but keeping some pages offline
(e.g. used right now by XEN and Hyper-V via set_online_page_callback()).
We are going to expose this flag to dump tools like makedumpfile. But
instead of exposing PG_balloon, let's generalize the concept of marking
pages as logically offline, so it can be reused for other purposes later
on.
Rename PG_balloon to PG_offline. This is an indicator that the page is
logically offline, the content stale and that it should not be touched
(e.g. a hypervisor would have to allocate backing storage in order for
the guest to dump an unused page). We can then e.g. exclude such pages
from dumps.
We replace and reuse KPF_BALLOON (23), as this shouldn't really harm
(and for now the semantics stay the same). In following patches, we
will make use of this bit also in other balloon drivers. While at it,
document PGTABLE.
[akpm@linux-foundation.org: fix comment text, per David]
Link: http://lkml.kernel.org/r/20181119101616.8901-3-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Acked-by: Konstantin Khlebnikov <koct9i@gmail.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Pankaj gupta <pagupta@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Christian Hansen <chansen3@cisco.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Pavel Tatashin <pasha.tatashin@oracle.com>
Cc: Alexander Duyck <alexander.h.duyck@linux.intel.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Miles Chen <miles.chen@mediatek.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Kazuhito Hagio <k-hagio@ab.jp.nec.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Baoquan He <bhe@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Haiyang Zhang <haiyangz@microsoft.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Julien Freche <jfreche@vmware.com>
Cc: Kairui Song <kasong@redhat.com>
Cc: "K. Y. Srinivasan" <kys@microsoft.com>
Cc: Len Brown <len.brown@intel.com>
Cc: Lianbo Jiang <lijiang@redhat.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Nadav Amit <namit@vmware.com>
Cc: Omar Sandoval <osandov@fb.com>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Stefano Stabellini <sstabellini@kernel.org>
Cc: Stephen Hemminger <sthemmin@microsoft.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: Xavier Deguillard <xdeguillard@vmware.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
Documentation/admin-guide/mm/pagemap.rst | 9 ++++++---
fs/proc/page.c | 4 ++--
include/linux/balloon_compaction.h | 8 ++++----
include/linux/page-flags.h | 11 +++++++----
include/uapi/linux/kernel-page-flags.h | 2 +-
tools/vm/page-types.c | 2 +-
6 files changed, 21 insertions(+), 15 deletions(-)
diff --git a/Documentation/admin-guide/mm/pagemap.rst b/Documentation/admin-guide/mm/pagemap.rst
index 3f7bade2c231e..340a5aee9b802 100644
--- a/Documentation/admin-guide/mm/pagemap.rst
+++ b/Documentation/admin-guide/mm/pagemap.rst
@@ -75,9 +75,10 @@ number of times a page is mapped.
20. NOPAGE
21. KSM
22. THP
- 23. BALLOON
+ 23. OFFLINE
24. ZERO_PAGE
25. IDLE
+ 26. PGTABLE
* ``/proc/kpagecgroup``. This file contains a 64-bit inode number of the
memory cgroup each page is charged to, indexed by PFN. Only available when
@@ -118,8 +119,8 @@ Short descriptions to the page flags
identical memory pages dynamically shared between one or more processes
22 - THP
contiguous pages which construct transparent hugepages
-23 - BALLOON
- balloon compaction page
+23 - OFFLINE
+ page is logically offline
24 - ZERO_PAGE
zero page for pfn_zero or huge_zero page
25 - IDLE
@@ -128,6 +129,8 @@ Short descriptions to the page flags
Note that this flag may be stale in case the page was accessed via
a PTE. To make sure the flag is up-to-date one has to read
``/sys/kernel/mm/page_idle/bitmap`` first.
+26 - PGTABLE
+ page is in use as a page table
IO related page flags
---------------------
diff --git a/fs/proc/page.c b/fs/proc/page.c
index 40b05e0d42746..544d1ee15aeec 100644
--- a/fs/proc/page.c
+++ b/fs/proc/page.c
@@ -152,8 +152,8 @@ u64 stable_page_flags(struct page *page)
else if (page_count(page) == 0 && is_free_buddy_page(page))
u |= 1 << KPF_BUDDY;
- if (PageBalloon(page))
- u |= 1 << KPF_BALLOON;
+ if (PageOffline(page))
+ u |= 1 << KPF_OFFLINE;
if (PageTable(page))
u |= 1 << KPF_PGTABLE;
diff --git a/include/linux/balloon_compaction.h b/include/linux/balloon_compaction.h
index cbe50da5a59d4..f111c780ef1df 100644
--- a/include/linux/balloon_compaction.h
+++ b/include/linux/balloon_compaction.h
@@ -95,7 +95,7 @@ extern int balloon_page_migrate(struct address_space *mapping,
static inline void balloon_page_insert(struct balloon_dev_info *balloon,
struct page *page)
{
- __SetPageBalloon(page);
+ __SetPageOffline(page);
__SetPageMovable(page, balloon->inode->i_mapping);
set_page_private(page, (unsigned long)balloon);
list_add(&page->lru, &balloon->pages);
@@ -111,7 +111,7 @@ static inline void balloon_page_insert(struct balloon_dev_info *balloon,
*/
static inline void balloon_page_delete(struct page *page)
{
- __ClearPageBalloon(page);
+ __ClearPageOffline(page);
__ClearPageMovable(page);
set_page_private(page, 0);
/*
@@ -141,13 +141,13 @@ static inline gfp_t balloon_mapping_gfp_mask(void)
static inline void balloon_page_insert(struct balloon_dev_info *balloon,
struct page *page)
{
- __SetPageBalloon(page);
+ __SetPageOffline(page);
list_add(&page->lru, &balloon->pages);
}
static inline void balloon_page_delete(struct page *page)
{
- __ClearPageBalloon(page);
+ __ClearPageOffline(page);
list_del(&page->lru);
}
diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
index 39b4494e29f1f..808b4183e30d0 100644
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -671,7 +671,7 @@ PAGEFLAG_FALSE(DoubleMap)
/* Reserve 0x0000007f to catch underflows of page_mapcount */
#define PAGE_MAPCOUNT_RESERVE -128
#define PG_buddy 0x00000080
-#define PG_balloon 0x00000100
+#define PG_offline 0x00000100
#define PG_kmemcg 0x00000200
#define PG_table 0x00000400
@@ -706,10 +706,13 @@ static __always_inline void __ClearPage##uname(struct page *page) \
PAGE_TYPE_OPS(Buddy, buddy)
/*
- * PageBalloon() is true for pages that are on the balloon page list
- * (see mm/balloon_compaction.c).
+ * PageOffline() indicates that the page is logically offline although the
+ * containing section is online. (e.g. inflated in a balloon driver or
+ * not onlined when onlining the section).
+ * The content of these pages is effectively stale. Such pages should not
+ * be touched (read/write/dump/save) except by their owner.
*/
-PAGE_TYPE_OPS(Balloon, balloon)
+PAGE_TYPE_OPS(Offline, offline)
/*
* If kmemcg is enabled, the buddy allocator will set PageKmemcg() on
diff --git a/include/uapi/linux/kernel-page-flags.h b/include/uapi/linux/kernel-page-flags.h
index 21b9113c69da4..6f2f2720f3ac2 100644
--- a/include/uapi/linux/kernel-page-flags.h
+++ b/include/uapi/linux/kernel-page-flags.h
@@ -32,7 +32,7 @@
#define KPF_KSM 21
#define KPF_THP 22
-#define KPF_BALLOON 23
+#define KPF_OFFLINE 23
#define KPF_ZERO_PAGE 24
#define KPF_IDLE 25
#define KPF_PGTABLE 26
diff --git a/tools/vm/page-types.c b/tools/vm/page-types.c
index 1ff3a6c0367b0..6f64b2b932342 100644
--- a/tools/vm/page-types.c
+++ b/tools/vm/page-types.c
@@ -133,7 +133,7 @@ static const char * const page_flag_names[] = {
[KPF_NOPAGE] = "n:nopage",
[KPF_KSM] = "x:ksm",
[KPF_THP] = "t:thp",
- [KPF_BALLOON] = "o:balloon",
+ [KPF_OFFLINE] = "o:offline",
[KPF_PGTABLE] = "g:pgtable",
[KPF_ZERO_PAGE] = "z:zero_page",
[KPF_IDLE] = "i:idle_page",
--
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