On 21.10.19 17:02, Michal Hocko wrote:
On Mon 21-10-19 16:19:26, David Hildenbrand wrote:
We have two types of users of page isolation:
1. Memory offlining: Offline memory so it can be unplugged. Memory won't
be touched.
2. Memory allocation: Allocate memory (e.g., alloc_contig_range()) to
become the owner of the memory and make use of it.
For example, in case we want to offline memory, we can ignore (skip over)
PageHWPoison() pages, as the memory won't get used. We can allow to
offline memory. In contrast, we don't want to allow to allocate such
memory.
Let's generalize the approach so we can special case other types of
pages we want to skip over in case we offline memory. While at it, also
pass the same flags to test_pages_isolated().
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Oscar Salvador <osalvador@xxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Anshuman Khandual <anshuman.khandual@xxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: Pingfan Liu <kernelfans@xxxxxxxxx>
Cc: Qian Cai <cai@xxxxxx>
Cc: Pavel Tatashin <pasha.tatashin@xxxxxxxxxx>
Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
Cc: Mike Rapoport <rppt@xxxxxxxxxxxxxxxxxx>
Cc: Alexander Duyck <alexander.h.duyck@xxxxxxxxxxxxxxx>
Suggested-by: Michal Hocko <mhocko@xxxxxxxx>
Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>
Yes, a highlevel flag makes more sense than requesting specific types of
pages to skip over.
Acked-by: Michal Hocko <mhocko@xxxxxxxx>
Please make the code easier to follow ...
---
include/linux/page-isolation.h | 4 ++--
mm/memory_hotplug.c | 8 +++++---
mm/page_alloc.c | 4 ++--
mm/page_isolation.c | 12 ++++++------
4 files changed, 15 insertions(+), 13 deletions(-)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index bf6b21f02154..b44712c7fdd7 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -8270,7 +8270,7 @@ bool has_unmovable_pages(struct zone *zone, struct page *page, int count,
* The HWPoisoned page may be not in buddy system, and
* page_count() is not 0.
*/
- if ((flags & SKIP_HWPOISON) && PageHWPoison(page))
+ if (flags & MEMORY_OFFLINE && PageHWPoison(page))
continue;
if (__PageMovable(page))
[...]
@@ -257,7 +258,7 @@ void undo_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn,
*/
static unsigned long
__test_page_isolated_in_pageblock(unsigned long pfn, unsigned long end_pfn,
- bool skip_hwpoisoned_pages)
+ int flags)
{
struct page *page;
@@ -274,7 +275,7 @@ __test_page_isolated_in_pageblock(unsigned long pfn, unsigned long end_pfn,
* simple way to verify that as VM_BUG_ON(), though.
*/
pfn += 1 << page_order(page);
- else if (skip_hwpoisoned_pages && PageHWPoison(page))
+ else if (flags & MEMORY_OFFLINE && PageHWPoison(page))
/* A HWPoisoned page cannot be also PageBuddy */
pfn++;
else
.. and use parentheses for the flag check.
Can do if you prefer :)
Thanks!
I'll resend both patches.
--
Thanks,
David / dhildenb
