online_pages()/offline_pages() theoretically allows us to work on
sub-section sizes. This is especially relevant in the context of
virtualization. It e.g. allows us to add/remove memory to Linux in a VM in
4MB chunks.
While the whole section is marked as online/offline, we have to know
the state of each page. E.g. to not read memory that is not online
during kexec() or to properly mark a section as offline as soon as all
contained pages are offline.
Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>
---
include/linux/page-flags.h | 10 ++++++++++
include/trace/events/mmflags.h | 9 ++++++++-
2 files changed, 18 insertions(+), 1 deletion(-)
diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
index e34a27727b9a..8ebc4bad7824 100644
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -49,6 +49,9 @@
* PG_hwpoison indicates that a page got corrupted in hardware and contains
* data with incorrect ECC bits that triggered a machine check. Accessing is
* not safe since it may cause another machine check. Don't touch!
+ *
+ * PG_offline indicates that a page is offline and the backing storage
+ * might already have been removed (virtualization). Don't touch!
*/
/*
@@ -100,6 +103,9 @@ enum pageflags {
#if defined(CONFIG_IDLE_PAGE_TRACKING) && defined(CONFIG_64BIT)
PG_young,
PG_idle,
+#endif
+#ifdef CONFIG_MEMORY_HOTPLUG
+ PG_offline, /* Page is offline. Don't touch */
#endif
__NR_PAGEFLAGS,
@@ -381,6 +387,10 @@ TESTCLEARFLAG(Young, young, PF_ANY)
PAGEFLAG(Idle, idle, PF_ANY)
#endif
+#ifdef CONFIG_MEMORY_HOTPLUG
+PAGEFLAG(Offline, offline, PF_ANY)
+#endif
+
/*
* On an anonymous page mapped into a user virtual memory area,
* page->mapping points to its anon_vma, not to a struct address_space;
diff --git a/include/trace/events/mmflags.h b/include/trace/events/mmflags.h
index a81cffb76d89..14c31209e34a 100644
--- a/include/trace/events/mmflags.h
+++ b/include/trace/events/mmflags.h
@@ -79,6 +79,12 @@
#define IF_HAVE_PG_IDLE(flag,string)
#endif
+#ifdef CONFIG_MEMORY_HOTPLUG
+#define IF_HAVE_PG_OFFLINE(flag,string) ,{1UL << flag, string}
+#else
+#define IF_HAVE_PG_OFFLINE(flag,string)
+#endif
+
#define __def_pageflag_names \
{1UL << PG_locked, "locked" }, \
{1UL << PG_waiters, "waiters" }, \
@@ -104,7 +110,8 @@ IF_HAVE_PG_MLOCK(PG_mlocked, "mlocked" ) \
IF_HAVE_PG_UNCACHED(PG_uncached, "uncached" ) \
IF_HAVE_PG_HWPOISON(PG_hwpoison, "hwpoison" ) \
IF_HAVE_PG_IDLE(PG_young, "young" ) \
-IF_HAVE_PG_IDLE(PG_idle, "idle" )
+IF_HAVE_PG_IDLE(PG_idle, "idle" ) \
+IF_HAVE_PG_OFFLINE(PG_offline, "offline" )
#define show_page_flags(flags) \
(flags) ? __print_flags(flags, "|", \
--
2.14.3
