This is useful to diagnose the reason for page allocation failure for
cases where there appear to be several free pages.
Example, with this alloc_pages(GFP_ATOMIC) failure:
swapper/0: page allocation failure: order:0, mode:0x0
...
Mem-info:
Normal per-cpu:
CPU 0: hi: 90, btch: 15 usd: 48
CPU 1: hi: 90, btch: 15 usd: 21
active_anon:0 inactive_anon:0 isolated_anon:0
active_file:0 inactive_file:84 isolated_file:0
unevictable:0 dirty:0 writeback:0 unstable:0
free:4026 slab_reclaimable:75 slab_unreclaimable:484
mapped:0 shmem:0 pagetables:0 bounce:0
Normal free:16104kB min:2296kB low:2868kB high:3444kB active_anon:0kB
inactive_anon:0kB active_file:0kB inactive_file:336kB unevictable:0kB
isolated(anon):0kB isolated(file):0kB present:331776kB mlocked:0kB
dirty:0kB writeback:0kB mapped:0kB shmem:0kB slab_reclaimable:300kB
slab_unreclaimable:1936kB kernel_stack:328kB pagetables:0kB unstable:0kB
bounce:0kB writeback_tmp:0kB pages_scanned:0 all_unreclaimable? no
lowmem_reserve[]: 0 0
Before the patch, it's hard (for me, at least) to say why all these free
chunks weren't considered for allocation:
Normal: 0*4kB 0*8kB 0*16kB 0*32kB 0*64kB 0*128kB 1*256kB 1*512kB
1*1024kB 1*2048kB 3*4096kB = 16128kB
After the patch, it's obvious that the reason is that all of these are
in the MIGRATE_CMA (C) freelist:
Normal: 0*4kB 0*8kB 0*16kB 0*32kB 0*64kB 0*128kB 1*256kB (C) 1*512kB
(C) 1*1024kB (C) 1*2048kB (C) 3*4096kB (C) = 16128kB
Signed-off-by: Rabin Vincent <rabin.vincent@xxxxxxxxxxxxxx>
---
mm/page_alloc.c | 42 ++++++++++++++++++++++++++++++++++++++++--
1 file changed, 40 insertions(+), 2 deletions(-)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index c13ea75..cbe5373 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -2818,6 +2818,31 @@ out:
#define K(x) ((x) << (PAGE_SHIFT-10))
+static void show_migration_types(unsigned char type)
+{
+ static const char types[MIGRATE_TYPES] = {
+ [MIGRATE_UNMOVABLE] = 'U',
+ [MIGRATE_RECLAIMABLE] = 'E',
+ [MIGRATE_MOVABLE] = 'M',
+ [MIGRATE_RESERVE] = 'R',
+#ifdef CONFIG_CMA
+ [MIGRATE_CMA] = 'C',
+#endif
+ [MIGRATE_ISOLATE] = 'I',
+ };
+ char tmp[MIGRATE_TYPES + 1];
+ char *p = tmp;
+ int i;
+
+ for (i = 0; i < MIGRATE_TYPES; i++) {
+ if (type & (1 << i))
+ *p++ = types[i];
+ }
+
+ *p = '\0';
+ printk("(%s) ", tmp);
+}
+
/*
* Show free area list (used inside shift_scroll-lock stuff)
* We also calculate the percentage fragmentation. We do this by counting the
@@ -2942,6 +2967,7 @@ void show_free_areas(unsigned int filter)
for_each_populated_zone(zone) {
unsigned long nr[MAX_ORDER], flags, order, total = 0;
+ unsigned char types[MAX_ORDER];
if (skip_free_areas_node(filter, zone_to_nid(zone)))
continue;
@@ -2950,12 +2976,24 @@ void show_free_areas(unsigned int filter)
spin_lock_irqsave(&zone->lock, flags);
for (order = 0; order < MAX_ORDER; order++) {
- nr[order] = zone->free_area[order].nr_free;
+ struct free_area *area = &zone->free_area[order];
+ int type;
+
+ nr[order] = area->nr_free;
total += nr[order] << order;
+
+ types[order] = 0;
+ for (type = 0; type < MIGRATE_TYPES; type++) {
+ if (!list_empty(&area->free_list[type]))
+ types[order] |= 1 << type;
+ }
}
spin_unlock_irqrestore(&zone->lock, flags);
- for (order = 0; order < MAX_ORDER; order++)
+ for (order = 0; order < MAX_ORDER; order++) {
printk("%lu*%lukB ", nr[order], K(1UL) << order);
+ if (nr[order])
+ show_migration_types(types[order]);
+ }
printk("= %lukB\n", K(total));
}
--
1.7.11.3
--
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