mm/page_alloc.c: clear out zone->lowmem_reserve[] if the zone is empty
When requesting memory allocation from a specific zone is not satisfied,
it will fall to lower zone to try allocating memory. In this case, lower
zone's ->lowmem_reserve[] will help protect its own memory resource. The
higher the relevant ->lowmem_reserve[] is, the harder the upper zone can
get memory from this lower zone.
However, this protection mechanism should be applied to populated zone,
but not an empty zone. So filling ->lowmem_reserve[] for empty zone is
not necessary, and may mislead people that it's valid data in that zone.
Node 2, zone DMA
pages free 0
min 0
low 0
high 0
spanned 0
present 0
managed 0
protection: (0, 0, 1024, 1024)
Node 2, zone DMA32
pages free 0
min 0
low 0
high 0
spanned 0
present 0
managed 0
protection: (0, 0, 1024, 1024)
Node 2, zone Normal
per-node stats
nr_inactive_anon 0
nr_active_anon 143
nr_inactive_file 0
nr_active_file 0
nr_unevictable 0
nr_slab_reclaimable 45
nr_slab_unreclaimable 254
Here clear out zone->lowmem_reserve[] if zone is empty.
Signed-off-by: Baoquan He <bhe@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/20200402140113.3696-3-bhe@redhat.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1 file changed