Re: [-next] lots of messages due to "mm, memory_hotplug: be more verbose for memory offline failures"

Michal Hocko
2018-12-17T16:39:55Z

On Mon 17-12-18 17:03:50, Michal Hocko wrote:
> On Mon 17-12-18 16:59:22, Heiko Carstens wrote:
> > Hi Michal,
> >
> > with linux-next as of today on s390 I see tons of messages like
> >
> > [ 20.536664] page dumped because: has_unmovable_pages
> > [ 20.536792] page:000003d081ff4080 count:1 mapcount:0 mapping:000000008ff88600 index:0x0 compound_mapcount: 0
> > [ 20.536794] flags: 0x3fffe0000010200(slab|head)
> > [ 20.536795] raw: 03fffe0000010200 0000000000000100 0000000000000200 000000008ff88600
> > [ 20.536796] raw: 0000000000000000 0020004100000000 ffffffff00000001 0000000000000000
> > [ 20.536797] page dumped because: has_unmovable_pages
> > [ 20.536814] page:000003d0823b0000 count:1 mapcount:0 mapping:0000000000000000 index:0x0
> > [ 20.536815] flags: 0x7fffe0000000000()
> > [ 20.536817] raw: 07fffe0000000000 0000000000000100 0000000000000200 0000000000000000
> > [ 20.536818] raw: 0000000000000000 0000000000000000 ffffffff00000001 0000000000000000
> >
> > bisect points to b323c049a999 ("mm, memory_hotplug: be more verbose for memory offline failures")
> > which is the first commit with which the messages appear.
>
> I would bet this is CMA allocator. How much is tons? Maybe we want a
> rate limit or the other user is not really interested in them at all?

In other words, this should silence those messages.

diff --git a/include/linux/page-isolation.h b/include/linux/page-isolation.h
index 4ae347cbc36d..4eb26d278046 100644
--- a/include/linux/page-isolation.h
+++ b/include/linux/page-isolation.h
@@ -30,8 +30,11 @@ static inline bool is_migrate_isolate(int migratetype)
}
#endif

+#define SKIP_HWPOISON 0x1
+#define REPORT_FAILURE 0x2
+
bool has_unmovable_pages(struct zone *zone, struct page *page, int count,
- int migratetype, bool skip_hwpoisoned_pages);
+ int migratetype, int flags);
void set_pageblock_migratetype(struct page *page, int migratetype);
int move_freepages_block(struct zone *zone, struct page *page,
int migratetype, int *num_movable);
@@ -44,10 +47,14 @@ int move_freepages_block(struct zone *zone, struct page *page,
* For isolating all pages in the range finally, the caller have to
* free all pages in the range. test_page_isolated() can be used for
* test it.
+ *
+ * The following flags are allowed (they can be combined in a bit mask)
+ * SKIP_HWPOISON - ignore hwpoison pages
+ * REPORT_FAILURE - report details about the failure to isolate the range
*/
int
start_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn,
- unsigned migratetype, bool skip_hwpoisoned_pages);
+ unsigned migratetype, int flags);

/*
* Changes MIGRATE_ISOLATE to MIGRATE_MOVABLE.
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index c82193db4be6..8537429d33a6 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -1226,7 +1226,7 @@ static bool is_pageblock_removable_nolock(struct page *page)
if (!zone_spans_pfn(zone, pfn))
return false;

- return !has_unmovable_pages(zone, page, 0, MIGRATE_MOVABLE, true);
+ return !has_unmovable_pages(zone, page, 0, MIGRATE_MOVABLE, SKIP_HWPOISON);
}

/* Checks if this range of memory is likely to be hot-removable. */
@@ -1577,7 +1577,8 @@ static int __ref __offline_pages(unsigned long start_pfn,

/* set above range as isolated */
ret = start_isolate_page_range(start_pfn, end_pfn,
- MIGRATE_MOVABLE, true);
+ MIGRATE_MOVABLE,
+ SKIP_HWPOISON | REPORT_FAILURE);
if (ret) {
mem_hotplug_done();
reason = "failure to isolate range";
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index ec2c7916dc2d..ee4043419791 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -7754,8 +7754,7 @@ void *__init alloc_large_system_hash(const char *tablename,
* race condition. So you can't expect this function should be exact.
*/
bool has_unmovable_pages(struct zone *zone, struct page *page, int count,
- int migratetype,
- bool skip_hwpoisoned_pages)
+ int migratetype, int flags)
{
unsigned long pfn, iter, found;

@@ -7818,7 +7817,7 @@ 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 (skip_hwpoisoned_pages && PageHWPoison(page))
+ if ((flags & SKIP_HWPOISON) && PageHWPoison(page))
continue;

if (__PageMovable(page))
@@ -7845,7 +7844,8 @@ bool has_unmovable_pages(struct zone *zone, struct page *page, int count,
return false;
unmovable:
WARN_ON_ONCE(zone_idx(zone) == ZONE_MOVABLE);
- dump_page(pfn_to_page(pfn+iter), "unmovable page");
+ if (flags & REPORT_FAILURE)
+ dump_page(pfn_to_page(pfn+iter), "unmovable page");
return true;
}

@@ -7972,8 +7972,7 @@ int alloc_contig_range(unsigned long start, unsigned long end,
*/

ret = start_isolate_page_range(pfn_max_align_down(start),
- pfn_max_align_up(end), migratetype,
- false);
+ pfn_max_align_up(end), migratetype, 0);
if (ret)
return ret;

diff --git a/mm/page_isolation.c b/mm/page_isolation.c
index 43e085608846..ce323e56b34d 100644
--- a/mm/page_isolation.c
+++ b/mm/page_isolation.c
@@ -15,8 +15,7 @@
#define CREATE_TRACE_POINTS
#include <trace/events/page_isolation.h>

-static int set_migratetype_isolate(struct page *page, int migratetype,
- bool skip_hwpoisoned_pages)
+static int set_migratetype_isolate(struct page *page, int migratetype, int isol_flags)
{
struct zone *zone;
unsigned long flags, pfn;
@@ -60,8 +59,7 @@ static int set_migratetype_isolate(struct page *page, int migratetype,
* FIXME: Now, memory hotplug doesn't call shrink_slab() by itself.
* We just check MOVABLE pages.
*/
- if (!has_unmovable_pages(zone, page, arg.pages_found, migratetype,
- skip_hwpoisoned_pages))
+ if (!has_unmovable_pages(zone, page, arg.pages_found, migratetype, flags))
ret = 0;

/*
@@ -185,7 +183,7 @@ __first_valid_page(unsigned long pfn, unsigned long nr_pages)
* prevents two threads from simultaneously working on overlapping ranges.
*/
int start_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn,
- unsigned migratetype, bool skip_hwpoisoned_pages)
+ unsigned migratetype, int flags)
{
unsigned long pfn;
unsigned long undo_pfn;
@@ -199,7 +197,7 @@ int start_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn,
pfn += pageblock_nr_pages) {
page = __first_valid_page(pfn, pageblock_nr_pages);
if (page &&
- set_migratetype_isolate(page, migratetype, skip_hwpoisoned_pages)) {
+ set_migratetype_isolate(page, migratetype, flags)) {
undo_pfn = pfn;
goto undo;
}
--
Michal Hocko
SUSE Labs