[PATCH v5 07/14] memory-hotplug: move pgdat_resize_lock into sparse_remove_one_section()

[Tang Chen]

In __remove_section(), we locked pgdat_resize_lock when calling
sparse_remove_one_section(). This lock will disable irq. But we don't need
to lock the whole function. If we do some work to free pagetables in
free_section_usemap(), we need to call flush_tlb_all(), which need
irq enabled. Otherwise the WARN_ON_ONCE() in smp_call_function_many()
will be triggered.

Signed-off-by: Tang Chen <tangchen@xxxxxxxxxxxxxx>
Signed-off-by: Lai Jiangshan <laijs@xxxxxxxxxxxxxx>
Signed-off-by: Wen Congyang <wency@xxxxxxxxxxxxxx>
---
 mm/memory_hotplug.c |    4 ----
 mm/sparse.c         |    5 ++++-
 2 files changed, 4 insertions(+), 5 deletions(-)

diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 34c656b..c12bd55 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -442,8 +442,6 @@ static int __remove_section(struct zone *zone, struct mem_section *ms)
 #else
 static int __remove_section(struct zone *zone, struct mem_section *ms)
 {
-	unsigned long flags;
-	struct pglist_data *pgdat = zone->zone_pgdat;
 	int ret = -EINVAL;
 
 	if (!valid_section(ms))
@@ -453,9 +451,7 @@ static int __remove_section(struct zone *zone, struct mem_section *ms)
 	if (ret)
 		return ret;
 
-	pgdat_resize_lock(pgdat, &flags);
 	sparse_remove_one_section(zone, ms);
-	pgdat_resize_unlock(pgdat, &flags);
 	return 0;
 }
 #endif
diff --git a/mm/sparse.c b/mm/sparse.c
index aadbb2a..05ca73a 100644
--- a/mm/sparse.c
+++ b/mm/sparse.c
@@ -796,8 +796,10 @@ static inline void clear_hwpoisoned_pages(struct page *memmap, int nr_pages)
 void sparse_remove_one_section(struct zone *zone, struct mem_section *ms)
 {
 	struct page *memmap = NULL;
-	unsigned long *usemap = NULL;
+	unsigned long *usemap = NULL, flags;
+	struct pglist_data *pgdat = zone->zone_pgdat;
 
+	pgdat_resize_lock(pgdat, &flags);
 	if (ms->section_mem_map) {
 		usemap = ms->pageblock_flags;
 		memmap = sparse_decode_mem_map(ms->section_mem_map,
@@ -805,6 +807,7 @@ void sparse_remove_one_section(struct zone *zone, struct mem_section *ms)
 		ms->section_mem_map = 0;
 		ms->pageblock_flags = NULL;
 	}
+	pgdat_resize_unlock(pgdat, &flags);
 
 	clear_hwpoisoned_pages(memmap, PAGES_PER_SECTION);
 	free_section_usemap(memmap, usemap);
-- 
1.7.1

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