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authorBaoquan He <bhe@redhat.com>2020-06-03 15:58:48 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2020-06-03 20:09:44 -0700
commit86aaf255437af88c0ff5d20a3c98e2b42fb0beda (patch)
treeedea7ba19fd7ace219199496351a5fe29550bec8
parent4ca7be24eeb3198dffdae9472d7464c8b8cadadb (diff)
mm/page_alloc.c: only tune sysctl_lowmem_reserve_ratio value once when changing it
Patch series "improvements about lowmem_reserve and /proc/zoneinfo", v2. This patch (of 3): When people write to /proc/sys/vm/lowmem_reserve_ratio to change sysctl_lowmem_reserve_ratio[], setup_per_zone_lowmem_reserve() is called to recalculate all ->lowmem_reserve[] for each zone of all nodes as below: static void setup_per_zone_lowmem_reserve(void) { ... for_each_online_pgdat(pgdat) { for (j = 0; j < MAX_NR_ZONES; j++) { ... while (idx) { ... if (sysctl_lowmem_reserve_ratio[idx] < 1) { sysctl_lowmem_reserve_ratio[idx] = 0; lower_zone->lowmem_reserve[j] = 0; } else { ... } } } } Meanwhile, here, sysctl_lowmem_reserve_ratio[idx] will be tuned if its value is smaller than '1'. As we know, sysctl_lowmem_reserve_ratio[] is set for zone without regarding to which node it belongs to. That means the tuning will be done on all nodes, even though it has been done in the first node. And the tuning will be done too even when init_per_zone_wmark_min() calls setup_per_zone_lowmem_reserve(), where actually nobody tries to change sysctl_lowmem_reserve_ratio[]. So now move the tuning into lowmem_reserve_ratio_sysctl_handler(), to make code logic more reasonable. Signed-off-by: Baoquan He <bhe@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Baoquan He <bhe@redhat.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: David Rientjes <rientjes@google.com> Link: http://lkml.kernel.org/r/20200402140113.3696-1-bhe@redhat.com Link: http://lkml.kernel.org/r/20200402140113.3696-2-bhe@redhat.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--mm/page_alloc.c11
1 files changed, 9 insertions, 2 deletions
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index a1a4f883b7f5..f3d5f0eb6159 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -7704,8 +7704,7 @@ static void setup_per_zone_lowmem_reserve(void)
idx--;
lower_zone = pgdat->node_zones + idx;
- if (sysctl_lowmem_reserve_ratio[idx] < 1) {
- sysctl_lowmem_reserve_ratio[idx] = 0;
+ if (!sysctl_lowmem_reserve_ratio[idx]) {
lower_zone->lowmem_reserve[j] = 0;
} else {
lower_zone->lowmem_reserve[j] =
@@ -7970,7 +7969,15 @@ int sysctl_min_slab_ratio_sysctl_handler(struct ctl_table *table, int write,
int lowmem_reserve_ratio_sysctl_handler(struct ctl_table *table, int write,
void __user *buffer, size_t *length, loff_t *ppos)
{
+ int i;
+
proc_dointvec_minmax(table, write, buffer, length, ppos);
+
+ for (i = 0; i < MAX_NR_ZONES; i++) {
+ if (sysctl_lowmem_reserve_ratio[i] < 1)
+ sysctl_lowmem_reserve_ratio[i] = 0;
+ }
+
setup_per_zone_lowmem_reserve();
return 0;
}