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| author |   Oscar Salvador <osalvador@suse.de> | 2018-10-26 15:03:58 -0700 |
|---|---|---|
| committer |   Linus Torvalds <torvalds@linux-foundation.org> | 2018-10-26 16:25:19 -0700 |
| commit | 7b0e0c0e35f5c7eca719404ca0e38bc964657330 (patch) | |
| tree | b5fcc54c93c369533547b1d91619f326eebc2f1b /mm/page_alloc.c | |
| parent | mm/swapfile.c: clear si->swap_map[] in swap_free_cluster() (diff) | |
| download | linux-dev-7b0e0c0e35f5c7eca719404ca0e38bc964657330.tar.xz linux-dev-7b0e0c0e35f5c7eca719404ca0e38bc964657330.zip | |
mm/page_alloc.c: clean up check_for_memory()
check_for_memory() looks a bit confusing. First of all, we have this:
if (N_MEMORY == N_NORMAL_MEMORY)
return;
Checking the ENUM declaration, looks like N_MEMORY canot be equal to
N_NORMAL_MEMORY.
I could not find where N_MEMORY is set to N_NORMAL_MEMORY, or the other
way around either, so unless I am missing something, this condition will
never evaluate to true. It makes sense to get rid of it.
Moving forward, the operations within the loop look a bit confusing as
well.
We set N_HIGH_MEMORY unconditionally, and then we set N_NORMAL_MEMORY in
case we have CONFIG_HIGHMEM (N_NORMAL_MEMORY != N_HIGH_MEMORY) and zone <=
ZONE_NORMAL. (N_HIGH_MEMORY falls back to N_NORMAL_MEMORY on
!CONFIG_HIGHMEM systems, and that is why we can just go ahead and set
N_HIGH_MEMORY unconditionally)
Although this works, it is a bit subtle.
I think that this could be easier to follow:
First, we should only set N_HIGH_MEMORY in case we have CONFIG_HIGHMEM.
And then we should set N_NORMAL_MEMORY in case zone <= ZONE_NORMAL,
without further checking whether we have CONFIG_HIGHMEM or not.
Link: http://lkml.kernel.org/r/20180828210158.4617-1-osalvador@techadventures.net
Signed-off-by: Oscar Salvador <osalvador@suse.de>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Michael Hocko <mhocko@suse.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Pavel Tatashin <pavel.tatashin@microsoft.com
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/page_alloc.c')
| -rw-r--r-- | mm/page_alloc.c | 9 |
1 files changed, 3 insertions, 6 deletions
diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 7e2fb6e38f34..747031c2352d 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -6803,15 +6803,12 @@ static void check_for_memory(pg_data_t *pgdat, int nid) { enum zone_type zone_type; - if (N_MEMORY == N_NORMAL_MEMORY) - return; - for (zone_type = 0; zone_type <= ZONE_MOVABLE - 1; zone_type++) { struct zone *zone = &pgdat->node_zones[zone_type]; if (populated_zone(zone)) { - node_set_state(nid, N_HIGH_MEMORY); - if (N_NORMAL_MEMORY != N_HIGH_MEMORY && - zone_type <= ZONE_NORMAL) + if (IS_ENABLED(CONFIG_HIGHMEM)) + node_set_state(nid, N_HIGH_MEMORY); + if (zone_type <= ZONE_NORMAL) node_set_state(nid, N_NORMAL_MEMORY); break; } |