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Date:   Tue, 31 Jul 2018 10:45:45 -0400
From:   Pavel Tatashin <pasha.tatashin@oracle.com>
To:     Oscar Salvador <osalvador@techadventures.net>
Cc:     Andrew Morton <akpm@linux-foundation.org>,
        Michal Hocko <mhocko@suse.com>,
        Vlastimil Babka <vbabka@suse.cz>,
        kirill.shutemov@linux.intel.com, iamjoonsoo.kim@lge.com,
        Mel Gorman <mgorman@suse.de>,
        Souptick Joarder <jrdr.linux@gmail.com>,
        Linux Memory Management List <linux-mm@kvack.org>,
        LKML <linux-kernel@vger.kernel.org>, osalvador@suse.de
Subject: Re: [PATCH] mm: make __paginginit based on CONFIG_MEMORY_HOTPLUG
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On 18-07-31 16:41:57, Oscar Salvador wrote:
> On Tue, Jul 31, 2018 at 08:49:11AM -0400, Pavel Tatashin wrote:
> > Hi Oscar,
> > 
> > Have you looked into replacing __paginginit via __meminit ? What is
> > the reason to keep both?
> Hi Pavel,
> 
> Actually, thinking a bit more about this, it might make sense to remove
> __paginginit altogether and keep only __meminit.
> Looking at the original commit, I think that it was put as a way to abstract it.
> 
> After the patchset [1] has been applied, only two functions marked as __paginginit
> remain, so it will be less hassle to replace that with __meminit.
> 
> I will send a v2 tomorrow to be applied on top of [1].
> 
> [1] https://patchwork.kernel.org/patch/10548861/
> 
> Thanks
> -- 
> Oscar Salvador
> SUSE L3
> 

Here the patch would look like this:

From e640b32dbd329bba5a785cc60050d5d7e1ca18ce Mon Sep 17 00:00:00 2001
From: Pavel Tatashin <pasha.tatashin@oracle.com>
Date: Tue, 31 Jul 2018 10:37:44 -0400
Subject: [PATCH] mm: remove __paginginit

__paginginit is the same thing as __meminit except for platforms without
sparsemem, there it is defined as __init.

Remove __paginginit and use __meminit. Use __ref in one single function
that merges __meminit and __init sections: setup_usemap().

Signed-off-by: Pavel Tatashin <pasha.tatashin@oracle.com>
---
 mm/internal.h   | 12 ------------
 mm/page_alloc.c | 19 ++++++++++---------
 2 files changed, 10 insertions(+), 21 deletions(-)

diff --git a/mm/internal.h b/mm/internal.h
index 33c22754d282..87256ae1bef8 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -389,18 +389,6 @@ static inline struct page *mem_map_next(struct page *iter,
 	return iter + 1;
 }
 
-/*
- * FLATMEM and DISCONTIGMEM configurations use alloc_bootmem_node,
- * so all functions starting at paging_init should be marked __init
- * in those cases. SPARSEMEM, however, allows for memory hotplug,
- * and alloc_bootmem_node is not used.
- */
-#ifdef CONFIG_SPARSEMEM
-#define __paginginit __meminit
-#else
-#define __paginginit __init
-#endif
-
 /* Memory initialisation debug and verification */
 enum mminit_level {
 	MMINIT_WARNING,
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 02e4b84038f8..92abe3eb151d 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -6122,7 +6122,7 @@ static unsigned long __init usemap_size(unsigned long zone_start_pfn, unsigned l
 	return usemapsize / 8;
 }
 
-static void __init setup_usemap(struct pglist_data *pgdat,
+static void __ref setup_usemap(struct pglist_data *pgdat,
 				struct zone *zone,
 				unsigned long zone_start_pfn,
 				unsigned long zonesize)
@@ -6142,7 +6142,7 @@ static inline void setup_usemap(struct pglist_data *pgdat, struct zone *zone,
 #ifdef CONFIG_HUGETLB_PAGE_SIZE_VARIABLE
 
 /* Initialise the number of pages represented by NR_PAGEBLOCK_BITS */
-void __paginginit set_pageblock_order(void)
+void __meminit set_pageblock_order(void)
 {
 	unsigned int order;
 
@@ -6170,14 +6170,14 @@ void __paginginit set_pageblock_order(void)
  * include/linux/pageblock-flags.h for the values of pageblock_order based on
  * the kernel config
  */
-void __paginginit set_pageblock_order(void)
+void __meminit set_pageblock_order(void)
 {
 }
 
 #endif /* CONFIG_HUGETLB_PAGE_SIZE_VARIABLE */
 
-static unsigned long __paginginit calc_memmap_size(unsigned long spanned_pages,
-						   unsigned long present_pages)
+static unsigned long __meminit calc_memmap_size(unsigned long spanned_pages,
+						unsigned long present_pages)
 {
 	unsigned long pages = spanned_pages;
 
@@ -6204,7 +6204,7 @@ static unsigned long __paginginit calc_memmap_size(unsigned long spanned_pages,
  *
  * NOTE: pgdat should get zeroed by caller.
  */
-static void __paginginit free_area_init_core(struct pglist_data *pgdat)
+static void __meminit free_area_init_core(struct pglist_data *pgdat)
 {
 	enum zone_type j;
 	int nid = pgdat->node_id;
@@ -6344,8 +6344,9 @@ static void __ref alloc_node_mem_map(struct pglist_data *pgdat)
 static void __ref alloc_node_mem_map(struct pglist_data *pgdat) { }
 #endif /* CONFIG_FLAT_NODE_MEM_MAP */
 
-void __paginginit free_area_init_node(int nid, unsigned long *zones_size,
-		unsigned long node_start_pfn, unsigned long *zholes_size)
+void __meminit free_area_init_node(int nid, unsigned long *zones_size,
+				   unsigned long node_start_pfn,
+				   unsigned long *zholes_size)
 {
 	pg_data_t *pgdat = NODE_DATA(nid);
 	unsigned long start_pfn = 0;
@@ -6390,7 +6391,7 @@ void __paginginit free_area_init_node(int nid, unsigned long *zones_size,
  * may be accessed (for example page_to_pfn() on some configuration accesses
  * flags). We must explicitly zero those struct pages.
  */
-void __paginginit zero_resv_unavail(void)
+void __meminit zero_resv_unavail(void)
 {
 	phys_addr_t start, end;
 	unsigned long pfn;
-- 
2.18.0