The patch titled
Subject: mm, memory_hotplug: be more verbose for memory offline failures
has been added to the -mm tree. Its filename is
mm-memory_hotplug-be-more-verbose-for-memory-offline-failures.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-memory_hotplug-be-more-verbose-for-memory-offline-failures.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-memory_hotplug-be-more-verbose-for-memory-offline-failures.patch
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------------------------------------------------------
From: Michal Hocko <mhocko@xxxxxxxx>
Subject: mm, memory_hotplug: be more verbose for memory offline failures
There is only very limited information printed when the memory offlining
fails:
[ 1984.506184] rac1 kernel: memory offlining [mem 0x82600000000-0x8267fffffff] failed due to signal backoff
This tells us that the failure is triggered by the userspace intervention
but it doesn't tell us much more about the underlying reason. It might be
that the page migration failes repeatedly and the userspace timeout
expires and send a signal or it might be some of the earlier steps
(isolation, memory notifier) takes too long.
If the migration failes then it would be really helpful to see which page
that and its state. The same applies to the isolation phase. If we fail
to isolate a page from the allocator then knowing the state of the page
would be helpful as well.
Dump the page state that fails to get isolated or migrated. This will
tell us more about the failure and what to focus on during debugging.
Link: http://lkml.kernel.org/r/20181107101830.17405-6-mhocko@xxxxxxxxxx
Signed-off-by: Michal Hocko <mhocko@xxxxxxxx>
Reviewed-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Baoquan He <bhe@xxxxxxxxxx>
Cc: Oscar Salvador <OSalvador@xxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/memory_hotplug.c | 12 ++++++++----
mm/page_alloc.c | 1 +
2 files changed, 9 insertions(+), 4 deletions(-)
--- a/mm/memory_hotplug.c~mm-memory_hotplug-be-more-verbose-for-memory-offline-failures
+++ a/mm/memory_hotplug.c
@@ -1388,10 +1388,8 @@ do_migrate_range(unsigned long start_pfn
page_is_file_cache(page));
} else {
-#ifdef CONFIG_DEBUG_VM
- pr_alert("failed to isolate pfn %lx\n", pfn);
+ pr_warn("failed to isolate pfn %lx\n", pfn);
dump_page(page, "isolation failed");
-#endif
put_page(page);
/* Because we don't have big zone->lock. we should
check this again here. */
@@ -1411,8 +1409,14 @@ do_migrate_range(unsigned long start_pfn
/* Allocate a new page from the nearest neighbor node */
ret = migrate_pages(&source, new_node_page, NULL, 0,
MIGRATE_SYNC, MR_MEMORY_HOTPLUG);
- if (ret)
+ if (ret) {
+ list_for_each_entry(page, &source, lru) {
+ pr_warn("migrating pfn %lx failed ",
+ page_to_pfn(page), ret);
+ dump_page(page, NULL);
+ }
putback_movable_pages(&source);
+ }
}
out:
return ret;
--- a/mm/page_alloc.c~mm-memory_hotplug-be-more-verbose-for-memory-offline-failures
+++ a/mm/page_alloc.c
@@ -7977,6 +7977,7 @@ bool has_unmovable_pages(struct zone *zo
return false;
unmovable:
WARN_ON_ONCE(zone_idx(zone) == ZONE_MOVABLE);
+ dump_page(pfn_to_page(pfn+iter), "has_unmovable_pages");
return true;
}
_
Patches currently in -mm which might be from mhocko@xxxxxxxx are
mm-memory_hotplug-check-zone_movable-in-has_unmovable_pages.patch
mm-print-more-information-about-mapping-in-__dump_page.patch
mm-lower-the-printk-loglevel-for-__dump_page-messages.patch
mm-memory_hotplug-drop-pointless-block-alignment-checks-from-__offline_pages.patch
mm-memory_hotplug-print-reason-for-the-offlining-failure.patch
mm-memory_hotplug-be-more-verbose-for-memory-offline-failures.patch
