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>
6cdb18ad98