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| author | Baoquan He <bhe@redhat.com> | 2020-06-03 15:58:52 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2020-06-03 20:09:44 -0700 |
| commit | f63661566fad43c0884ad879e6ff07c55ed890f4 (patch) | |
| tree | 4d6806c5a385979541dcfc1da1ce3406f3dc3a51 /mm/page_alloc.c | |
| parent | 86aaf255437af88c0ff5d20a3c98e2b42fb0beda (diff) | |
| download | linux-f63661566fad43c0884ad879e6ff07c55ed890f4.tar.gz linux-f63661566fad43c0884ad879e6ff07c55ed890f4.tar.xz | |
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>
Diffstat (limited to 'mm/page_alloc.c')
| -rw-r--r-- | mm/page_alloc.c | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/mm/page_alloc.c b/mm/page_alloc.c index f3d5f0eb6159..5b8d0966d429 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -7704,8 +7704,10 @@ static void setup_per_zone_lowmem_reserve(void) idx--; lower_zone = pgdat->node_zones + idx; - if (!sysctl_lowmem_reserve_ratio[idx]) { + if (!sysctl_lowmem_reserve_ratio[idx] || + !zone_managed_pages(lower_zone)) { lower_zone->lowmem_reserve[j] = 0; + continue; } else { lower_zone->lowmem_reserve[j] = managed_pages / sysctl_lowmem_reserve_ratio[idx]; |