The patch titled
Subject: mm: page_alloc: dump migrate-failed pages
has been added to the -mm tree. Its filename is
mm-page_alloc-dump-migrate-failed-pages.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/mm-page_alloc-dump-migrate-failed-pages.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/mm-page_alloc-dump-migrate-failed-pages.patch
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------------------------------------------------------
From: Minchan Kim <minchan@xxxxxxxxxx>
Subject: mm: page_alloc: dump migrate-failed pages
Currently, debugging CMA allocation failures is quite limited. The most
common source of these failures seems to be page migration which doesn't
provide any useful information on the reason of the failure by itself.
alloc_contig_range can report those failures as it holds a list of
migrate-failed pages.
The information logged by dump_page() has already proven helpful for
debugging allocation issues, like identifying long-term pinnings on
ZONE_MOVABLE or MIGRATE_CMA.
Let's use the dynamic debugging infrastructure, such that we avoid
flooding the logs and creating a lot of noise on frequent
alloc_contig_range() calls. This information is helpful for debugging
only.
There are two ifdefery conditions to support common dyndbg options:
- CONFIG_DYNAMIC_DEBUG_CORE && DYNAMIC_DEBUG_MODULE
It aims for supporting the feature with only specific file with
adding ccflags.
- CONFIG_DYNAMIC_DEBUG
It aims for supporting the feature with system wide globally.
A simple example to enable the feature:
Admin could enable the dump like this(by default, disabled)
echo "func alloc_contig_dump_pages +p" > control
Admin could disable it.
echo "func alloc_contig_dump_pages =_" > control
Detail goes Documentation/admin-guide/dynamic-debug-howto.rst
A concern is utility functions in dump_page use inconsistent
loglevels. In the future, we might want to make the loglevels
used inside dump_page() consistent and eventually rework the way
we log the information here. See [1].
[1] https://lore.kernel.org/linux-mm/YEh4doXvyuRl5BDB@xxxxxxxxxx/
Link: https://lkml.kernel.org/r/20210311194042.825152-1-minchan@xxxxxxxxxx
Signed-off-by: Minchan Kim <minchan@xxxxxxxxxx>
Reviewed-by: David Hildenbrand <david@xxxxxxxxxx>
Cc: John Dias <joaodias@xxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: Jason Baron <jbaron@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/page_alloc.c | 22 ++++++++++++++++++++++
1 file changed, 22 insertions(+)
--- a/mm/page_alloc.c~mm-page_alloc-dump-migrate-failed-pages
+++ a/mm/page_alloc.c
@@ -8473,6 +8473,27 @@ static unsigned long pfn_max_align_up(un
pageblock_nr_pages));
}
+#if defined(CONFIG_DYNAMIC_DEBUG) || \
+ (defined(CONFIG_DYNAMIC_DEBUG_CORE) && defined(DYNAMIC_DEBUG_MODULE))
+/* Usage: See admin-guide/dynamic-debug-howto.rst */
+static void alloc_contig_dump_pages(struct list_head *page_list)
+{
+ DEFINE_DYNAMIC_DEBUG_METADATA(descriptor, "migrate failure");
+
+ if (DYNAMIC_DEBUG_BRANCH(descriptor)) {
+ struct page *page;
+
+ dump_stack();
+ list_for_each_entry(page, page_list, lru)
+ dump_page(page, "migration failure");
+ }
+}
+#else
+static inline void alloc_contig_dump_pages(struct list_head *page_list)
+{
+}
+#endif
+
/* [start, end) must belong to a single zone. */
static int __alloc_contig_migrate_range(struct compact_control *cc,
unsigned long start, unsigned long end)
@@ -8516,6 +8537,7 @@ static int __alloc_contig_migrate_range(
NULL, (unsigned long)&mtc, cc->mode, MR_CONTIG_RANGE);
}
if (ret < 0) {
+ alloc_contig_dump_pages(&cc->migratepages);
putback_movable_pages(&cc->migratepages);
return ret;
}
_
Patches currently in -mm which might be from minchan@xxxxxxxxxx are
mm-remove-lru_add_drain_all-in-alloc_contig_range.patch
mm-page_alloc-dump-migrate-failed-pages.patch
mm-vmstat-add-cma-statistics.patch
