Commit 0c04015d authored by Ye Liu's avatar Ye Liu Committed by Andrew Morton
Browse files

mm/page_alloc: simplify lowmem_reserve max calculation 

Use max() to find the maximum lowmem_reserve value and min_t() to cap it
to managed_pages in calculate_totalreserve_pages(), instead of open-coding
the comparisons.  No functional change.

[liuye@kylinos.cn: fix layout, use min_t]
  Link: https://lkml.kernel.org/r/20250815024509.37900-1-ye.liu@linux.dev
Link: https://lkml.kernel.org/r/20250814090053.22241-1-ye.liu@linux.dev


Signed-off-by: default avatarYe Liu <liuye@kylinos.cn>
Acked-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
Acked-by: default avatarZi Yan <ziy@nvidia.com>
Reviewed-by: default avatarWei Yang <richard.weiyang@gmail.com>
Cc: Brendan Jackman <jackmanb@google.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent a3f451ad

mm/page_alloc.c

+3 −6
Original line number Diff line number Diff line
@@ -6236,16 +6236,13 @@ static void calculate_totalreserve_pages(void) 
			unsigned long managed_pages = zone_managed_pages(zone);



			/* Find valid and maximum lowmem_reserve in the zone */

			for (j = i; j < MAX_NR_ZONES; j++) {

				if (zone->lowmem_reserve[j] > max)

					max = zone->lowmem_reserve[j];

			}

			for (j = i; j < MAX_NR_ZONES; j++)

				max = max(max, zone->lowmem_reserve[j]);



			/* we treat the high watermark as reserved pages. */

			max += high_wmark_pages(zone);



			if (max > managed_pages)

				max = managed_pages;

			max = min_t(unsigned long, max, managed_pages);



			pgdat->totalreserve_pages += max;