[PATCH v3 05/12] mm: cleanup sparse_init_one_section() return value

From: Dan Williams
Date: Thu Jan 19 2017 - 17:24:00 EST


We mark and check that the section is present under a spin_lock() in
sparse_add_one_section(), so the lock ensures it will not change between
those 2 events. Also, we do not check the -EBUSY return value in
sparse_init(). Just make sparse_init_one_section() return void and clean
up the error handling.

Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Logan Gunthorpe <logang@xxxxxxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Stephen Bates <stephen.bates@xxxxxxxxxxxxx>
Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
---
mm/sparse.c | 21 ++++++---------------
1 file changed, 6 insertions(+), 15 deletions(-)

diff --git a/mm/sparse.c b/mm/sparse.c
index 91e1908db23d..59966a3e8ff0 100644
--- a/mm/sparse.c
+++ b/mm/sparse.c
@@ -231,19 +231,14 @@ struct page *sparse_decode_mem_map(unsigned long coded_mem_map, unsigned long pn
return ((struct page *)coded_mem_map) + section_nr_to_pfn(pnum);
}

-static int __meminit sparse_init_one_section(struct mem_section *ms,
+static void __meminit sparse_init_one_section(struct mem_section *ms,
unsigned long pnum, struct page *mem_map,
struct mem_section_usage *usage)
{
- if (!present_section(ms))
- return -EINVAL;
-
ms->section_mem_map &= ~SECTION_MAP_MASK;
ms->section_mem_map |= sparse_encode_mem_map(mem_map, pnum) |
SECTION_HAS_MEM_MAP;
ms->usage = usage;
-
- return 1;
}

unsigned long usemap_size(void)
@@ -690,11 +685,6 @@ static void free_map_bootmem(struct page *memmap)
#endif /* CONFIG_MEMORY_HOTREMOVE */
#endif /* CONFIG_SPARSEMEM_VMEMMAP */

-/*
- * returns the number of sections whose mem_maps were properly
- * set. If this is <=0, then that means that the passed-in
- * map was not consumed and must be freed.
- */
int __meminit sparse_add_one_section(struct zone *zone, unsigned long start_pfn)
{
unsigned long section_nr = pfn_to_section_nr(start_pfn);
@@ -725,7 +715,7 @@ int __meminit sparse_add_one_section(struct zone *zone, unsigned long start_pfn)

ms = __pfn_to_section(start_pfn);
if (ms->section_mem_map & SECTION_MARKED_PRESENT) {
- ret = -EEXIST;
+ ret = -EBUSY;
goto out;
}

@@ -733,15 +723,16 @@ int __meminit sparse_add_one_section(struct zone *zone, unsigned long start_pfn)

ms->section_mem_map |= SECTION_MARKED_PRESENT;

- ret = sparse_init_one_section(ms, section_nr, memmap, usage);
+ sparse_init_one_section(ms, section_nr, memmap, usage);

out:
pgdat_resize_unlock(pgdat, &flags);
- if (ret <= 0) {
+ if (ret < 0 && ret != -EEXIST) {
kfree(usage);
__kfree_section_memmap(memmap);
+ return ret;
}
- return ret;
+ return 0;
}

#ifdef CONFIG_MEMORY_HOTREMOVE