From 3c381db1fac80373f2cc0d8c1d0bcfbf8bd4fb57 Mon Sep 17 00:00:00 2001
From: David Hildenbrand <david@redhat.com>
Date: Thu, 25 Feb 2021 17:16:40 -0800
Subject: [PATCH] mm/page_alloc: count CMA pages per zone and print them in
/proc/zoneinfo
Let's count the number of CMA pages per zone and print them in
/proc/zoneinfo.
Having access to the total number of CMA pages per zone is helpful for
debugging purposes to know where exactly the CMA pages ended up, and to
figure out how many pages of a zone might behave differently, even after
some of these pages might already have been allocated.
As one example, CMA pages part of a kernel zone cannot be used for
ordinary kernel allocations but instead behave more like ZONE_MOVABLE.
For now, we are only able to get the global nr+free cma pages from
/proc/meminfo and the free cma pages per zone from /proc/zoneinfo.
Example after this patch when booting a 6 GiB QEMU VM with
"hugetlb_cma=2G":
# cat /proc/zoneinfo | grep cma
cma 0
nr_free_cma 0
cma 0
nr_free_cma 0
cma 524288
nr_free_cma 493016
cma 0
cma 0
# cat /proc/meminfo | grep Cma
CmaTotal: 2097152 kB
CmaFree: 1972064 kB
Note: We print even without CONFIG_CMA, just like "nr_free_cma"; this way,
one can be sure when spotting "cma 0", that there are definetly no
CMA pages located in a zone.
[david@redhat.com: v2]
Link: https://lkml.kernel.org/r/20210128164533.18566-1-david@redhat.com
[david@redhat.com: v3]
Link: https://lkml.kernel.org/r/20210129113451.22085-1-david@redhat.com
Link: https://lkml.kernel.org/r/20210127101813.6370-3-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "Peter Zijlstra (Intel)" <peterz@infradead.org>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Wei Yang <richard.weiyang@linux.alibaba.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
include/linux/mmzone.h | 15 +++++++++++++++
mm/page_alloc.c | 1 +
mm/vmstat.c | 6 ++++--
3 files changed, 20 insertions(+), 2 deletions(-)
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 9198b7ade85ff..5f9c4dad73eda 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -503,6 +503,9 @@ struct zone {
* bootmem allocator):
* managed_pages = present_pages - reserved_pages;
*
+ * cma pages is present pages that are assigned for CMA use
+ * (MIGRATE_CMA).
+ *
* So present_pages may be used by memory hotplug or memory power
* management logic to figure out unmanaged pages by checking
* (present_pages - managed_pages). And managed_pages should be used
@@ -527,6 +530,9 @@ struct zone {
atomic_long_t managed_pages;
unsigned long spanned_pages;
unsigned long present_pages;
+#ifdef CONFIG_CMA
+ unsigned long cma_pages;
+#endif
const char *name;
@@ -624,6 +630,15 @@ static inline unsigned long zone_managed_pages(struct zone *zone)
return (unsigned long)atomic_long_read(&zone->managed_pages);
}
+static inline unsigned long zone_cma_pages(struct zone *zone)
+{
+#ifdef CONFIG_CMA
+ return zone->cma_pages;
+#else
+ return 0;
+#endif
+}
+
static inline unsigned long zone_end_pfn(const struct zone *zone)
{
return zone->zone_start_pfn + zone->spanned_pages;
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index ddccc59f2f72a..3e4b29ee2b1e4 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -2168,6 +2168,7 @@ void __init init_cma_reserved_pageblock(struct page *page)
}
adjust_managed_page_count(page, pageblock_nr_pages);
+ page_zone(page)->cma_pages += pageblock_nr_pages;
}
#endif
diff --git a/mm/vmstat.c b/mm/vmstat.c
index a0e9495422044..6cdf789ced5ea 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -1637,14 +1637,16 @@ static void zoneinfo_show_print(struct seq_file *m, pg_data_t *pgdat,
"\n high %lu"
"\n spanned %lu"
"\n present %lu"
- "\n managed %lu",
+ "\n managed %lu"
+ "\n cma %lu",
zone_page_state(zone, NR_FREE_PAGES),
min_wmark_pages(zone),
low_wmark_pages(zone),
high_wmark_pages(zone),
zone->spanned_pages,
zone->present_pages,
- zone_managed_pages(zone));
+ zone_managed_pages(zone),
+ zone_cma_pages(zone));
seq_printf(m,
"\n protection: (%ld",
--
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