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authorHeiko Carstens <heiko.carstens@de.ibm.com>2015-12-30 01:54:32 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2015-12-30 04:45:49 +0300
commit6cdb18ad98a49f7e9b95d538a0614cde827404b8 (patch)
treefb698abbb79de2d8b90d1042517bd08ba375c988 /include/linux/vmstat.h
parentcc28d6d80f6ab494b10f0e2ec949eacd610f66e3 (diff)
downloadlinux-6cdb18ad98a49f7e9b95d538a0614cde827404b8.tar.xz
mm/vmstat: fix overflow in mod_zone_page_state()
mod_zone_page_state() takes a "delta" integer argument. delta contains the number of pages that should be added or subtracted from a struct zone's vm_stat field. If a zone is larger than 8TB this will cause overflows. E.g. for a zone with a size slightly larger than 8TB the line mod_zone_page_state(zone, NR_ALLOC_BATCH, zone->managed_pages); in mm/page_alloc.c:free_area_init_core() will result in a negative result for the NR_ALLOC_BATCH entry within the zone's vm_stat, since 8TB contain 0x8xxxxxxx pages which will be sign extended to a negative value. Fix this by changing the delta argument to long type. This could fix an early boot problem seen on s390, where we have a 9TB system with only one node. ZONE_DMA contains 2GB and ZONE_NORMAL the rest. The system is trying to allocate a GFP_DMA page but ZONE_DMA is completely empty, so it tries to reclaim pages in an endless loop. This was seen on a heavily patched 3.10 kernel. One possible explaination seem to be the overflows caused by mod_zone_page_state(). Unfortunately I did not have the chance to verify that this patch actually fixes the problem, since I don't have access to the system right now. However the overflow problem does exist anyway. Given the description that a system with slightly less than 8TB does work, this seems to be a candidate for the observed problem. Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Christoph Lameter <cl@linux.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include/linux/vmstat.h')
-rw-r--r--include/linux/vmstat.h6
1 files changed, 3 insertions, 3 deletions
diff --git a/include/linux/vmstat.h b/include/linux/vmstat.h
index 5dbc8b0ee567..3e5d9075960f 100644
--- a/include/linux/vmstat.h
+++ b/include/linux/vmstat.h
@@ -176,11 +176,11 @@ extern void zone_statistics(struct zone *, struct zone *, gfp_t gfp);
#define sub_zone_page_state(__z, __i, __d) mod_zone_page_state(__z, __i, -(__d))
#ifdef CONFIG_SMP
-void __mod_zone_page_state(struct zone *, enum zone_stat_item item, int);
+void __mod_zone_page_state(struct zone *, enum zone_stat_item item, long);
void __inc_zone_page_state(struct page *, enum zone_stat_item);
void __dec_zone_page_state(struct page *, enum zone_stat_item);
-void mod_zone_page_state(struct zone *, enum zone_stat_item, int);
+void mod_zone_page_state(struct zone *, enum zone_stat_item, long);
void inc_zone_page_state(struct page *, enum zone_stat_item);
void dec_zone_page_state(struct page *, enum zone_stat_item);
@@ -205,7 +205,7 @@ void set_pgdat_percpu_threshold(pg_data_t *pgdat,
* The functions directly modify the zone and global counters.
*/
static inline void __mod_zone_page_state(struct zone *zone,
- enum zone_stat_item item, int delta)
+ enum zone_stat_item item, long delta)
{
zone_page_state_add(delta, zone, item);
}