diff mbox series

[v3,1/2] mm: pass page count and reserved to __init_single_page

Message ID 20230926023341.991124-2-yajun.deng@linux.dev
State New
Headers
Series mm: Don't set and reset page count in MEMINIT_EARLY |

Commit Message

Yajun Deng Sept. 26, 2023, 2:33 a.m. UTC 
  When we init a single page, we need to mark this page reserved if it
does. And some pages may not need to set page count, such as compound
pages.

Introduce enum init_page_flags, the caller init page count and mark page
reserved by passing INIT_PAGE_COUNT and INIT_PAGE_RESERVED.

Signed-off-by: Yajun Deng <yajun.deng@linux.dev>
---
v3: Introduce enum init_page_flags.
v2: Introduce INIT_PAGE_COUNT and INIT_PAGE_RESERVED.
v1: https://lore.kernel.org/all/20230922070923.355656-1-yajun.deng@linux.dev/
---
 mm/hugetlb.c  |  2 +-
 mm/internal.h |  8 +++++++-
 mm/mm_init.c  | 31 +++++++++++++++++--------------
 3 files changed, 25 insertions(+), 16 deletions(-)

Comments

Yajun Deng Sept. 26, 2023, 7:57 a.m. UTC | #1 
On 2023/9/26 15:44, David Hildenbrand wrote:
> On 26.09.23 04:33, Yajun Deng wrote:
>> When we init a single page, we need to mark this page reserved if it
>> does. 
>
> I failed to parse the last part of this sentence.
>
>> And some pages may not need to set page count, such as compound
>> pages.
>
> Usually, the refcount of all tail pages *must* be zero. Otherwise, 
> get_page_unless_zero() would work on tail pages.
>
> Can you elaborate why it should be okay here?
>
>
It means the following code in memmap_init_compound().

-               __init_zone_device_page(page, pfn, zone_idx, nid, pgmap);
+               __init_zone_device_page(page, pfn, zone_idx, nid, pgmap, 0);
                 prep_compound_tail(head, pfn - head_pfn);
                 set_page_count(page, 0);

As we can see, it will reset the page count by 'set_page_count(page, 0)'.

Therefore, we don't need to set page count in __init_zone_device_page(). 
I wasn't clear enough in the commit.

Maybe we can remove the 'set_page_count(page, 0)',  But I didn't do 
that, just to be safe.
Mike Rapoport Sept. 28, 2023, 5:30 a.m. UTC | #2 
On Tue, Sep 26, 2023 at 10:33:40AM +0800, Yajun Deng wrote:
> When we init a single page, we need to mark this page reserved if it
> does. And some pages may not need to set page count, such as compound
> pages.
> 
> Introduce enum init_page_flags, the caller init page count and mark page
> reserved by passing INIT_PAGE_COUNT and INIT_PAGE_RESERVED.
> 
> Signed-off-by: Yajun Deng <yajun.deng@linux.dev>
> ---
> v3: Introduce enum init_page_flags.
> v2: Introduce INIT_PAGE_COUNT and INIT_PAGE_RESERVED.
> v1: https://lore.kernel.org/all/20230922070923.355656-1-yajun.deng@linux.dev/
> ---
>  mm/hugetlb.c  |  2 +-
>  mm/internal.h |  8 +++++++-
>  mm/mm_init.c  | 31 +++++++++++++++++--------------
>  3 files changed, 25 insertions(+), 16 deletions(-)
> 
> diff --git a/mm/mm_init.c b/mm/mm_init.c
> index 06a72c223bce..07fe7e489769 100644
> --- a/mm/mm_init.c
> +++ b/mm/mm_init.c
> @@ -1041,7 +1043,7 @@ static void __ref memmap_init_compound(struct page *head,
>  	for (pfn = head_pfn + 1; pfn < end_pfn; pfn++) {
>  		struct page *page = pfn_to_page(pfn);
>  
> -		__init_zone_device_page(page, pfn, zone_idx, nid, pgmap);
> +		__init_zone_device_page(page, pfn, zone_idx, nid, pgmap, 0);

I think the first patch should not contain any functional changes, but only
add the flags parameter to __init_single_page().

>  		prep_compound_tail(head, pfn - head_pfn);
>  		set_page_count(page, 0);
>
diff mbox series

Patch

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index de220e3ff8be..cb282eadc729 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -3196,7 +3196,7 @@  static void __init hugetlb_folio_init_tail_vmemmap(struct folio *folio,
 	for (pfn = head_pfn + start_page_number; pfn < end_pfn; pfn++) {
 		struct page *page = pfn_to_page(pfn);
 
-		__init_single_page(page, pfn, zone, nid);
+		__init_single_page(page, pfn, zone, nid, INIT_PAGE_COUNT);
 		prep_compound_tail((struct page *)folio, pfn - head_pfn);
 		ret = page_ref_freeze(page, 1);
 		VM_BUG_ON(!ret);
diff --git a/mm/internal.h b/mm/internal.h
index d7916f1e9e98..449891ad7fdb 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -1209,8 +1209,14 @@  struct vma_prepare {
 	struct vm_area_struct *remove2;
 };
 
+enum init_page_flags {
+	INIT_PAGE_COUNT    = (1 << 0),
+	INIT_PAGE_RESERVED = (1 << 1),
+};
+
 void __meminit __init_single_page(struct page *page, unsigned long pfn,
-				unsigned long zone, int nid);
+				  unsigned long zone, int nid,
+				  enum init_page_flags flags);
 
 /* shrinker related functions */
 unsigned long shrink_slab(gfp_t gfp_mask, int nid, struct mem_cgroup *memcg,
diff --git a/mm/mm_init.c b/mm/mm_init.c
index 06a72c223bce..07fe7e489769 100644
--- a/mm/mm_init.c
+++ b/mm/mm_init.c
@@ -557,11 +557,11 @@  static void __init find_zone_movable_pfns_for_nodes(void)
 }
 
 void __meminit __init_single_page(struct page *page, unsigned long pfn,
-				unsigned long zone, int nid)
+				  unsigned long zone, int nid,
+				  enum init_page_flags flags)
 {
 	mm_zero_struct_page(page);
 	set_page_links(page, zone, nid, pfn);
-	init_page_count(page);
 	page_mapcount_reset(page);
 	page_cpupid_reset_last(page);
 	page_kasan_tag_reset(page);
@@ -572,6 +572,10 @@  void __meminit __init_single_page(struct page *page, unsigned long pfn,
 	if (!is_highmem_idx(zone))
 		set_page_address(page, __va(pfn << PAGE_SHIFT));
 #endif
+	if (flags & INIT_PAGE_COUNT)
+		init_page_count(page);
+	if (flags & INIT_PAGE_RESERVED)
+		__SetPageReserved(page);
 }
 
 #ifdef CONFIG_NUMA
@@ -714,7 +718,7 @@  static void __meminit init_reserved_page(unsigned long pfn, int nid)
 		if (zone_spans_pfn(zone, pfn))
 			break;
 	}
-	__init_single_page(pfn_to_page(pfn), pfn, zid, nid);
+	__init_single_page(pfn_to_page(pfn), pfn, zid, nid, INIT_PAGE_COUNT);
 }
 #else
 static inline void pgdat_set_deferred_range(pg_data_t *pgdat) {}
@@ -821,8 +825,8 @@  static void __init init_unavailable_range(unsigned long spfn,
 			pfn = pageblock_end_pfn(pfn) - 1;
 			continue;
 		}
-		__init_single_page(pfn_to_page(pfn), pfn, zone, node);
-		__SetPageReserved(pfn_to_page(pfn));
+		__init_single_page(pfn_to_page(pfn), pfn, zone, node,
+				   INIT_PAGE_COUNT | INIT_PAGE_RESERVED);
 		pgcnt++;
 	}
 
@@ -884,7 +888,7 @@  void __meminit memmap_init_range(unsigned long size, int nid, unsigned long zone
 		}
 
 		page = pfn_to_page(pfn);
-		__init_single_page(page, pfn, zone, nid);
+		__init_single_page(page, pfn, zone, nid, INIT_PAGE_COUNT);
 		if (context == MEMINIT_HOTPLUG)
 			__SetPageReserved(page);
 
@@ -965,11 +969,9 @@  static void __init memmap_init(void)
 #ifdef CONFIG_ZONE_DEVICE
 static void __ref __init_zone_device_page(struct page *page, unsigned long pfn,
 					  unsigned long zone_idx, int nid,
-					  struct dev_pagemap *pgmap)
+					  struct dev_pagemap *pgmap,
+					  unsigned int flags)
 {
-
-	__init_single_page(page, pfn, zone_idx, nid);
-
 	/*
 	 * Mark page reserved as it will need to wait for onlining
 	 * phase for it to be fully associated with a zone.
@@ -977,7 +979,7 @@  static void __ref __init_zone_device_page(struct page *page, unsigned long pfn,
 	 * We can use the non-atomic __set_bit operation for setting
 	 * the flag as we are still initializing the pages.
 	 */
-	__SetPageReserved(page);
+	__init_single_page(page, pfn, zone_idx, nid, flags | INIT_PAGE_RESERVED);
 
 	/*
 	 * ZONE_DEVICE pages union ->lru with a ->pgmap back pointer
@@ -1041,7 +1043,7 @@  static void __ref memmap_init_compound(struct page *head,
 	for (pfn = head_pfn + 1; pfn < end_pfn; pfn++) {
 		struct page *page = pfn_to_page(pfn);
 
-		__init_zone_device_page(page, pfn, zone_idx, nid, pgmap);
+		__init_zone_device_page(page, pfn, zone_idx, nid, pgmap, 0);
 		prep_compound_tail(head, pfn - head_pfn);
 		set_page_count(page, 0);
 
@@ -1084,7 +1086,8 @@  void __ref memmap_init_zone_device(struct zone *zone,
 	for (pfn = start_pfn; pfn < end_pfn; pfn += pfns_per_compound) {
 		struct page *page = pfn_to_page(pfn);
 
-		__init_zone_device_page(page, pfn, zone_idx, nid, pgmap);
+		__init_zone_device_page(page, pfn, zone_idx, nid, pgmap,
+					INIT_PAGE_COUNT);
 
 		if (pfns_per_compound == 1)
 			continue;
@@ -2058,7 +2061,7 @@  static unsigned long  __init deferred_init_pages(struct zone *zone,
 		} else {
 			page++;
 		}
-		__init_single_page(page, pfn, zid, nid);
+		__init_single_page(page, pfn, zid, nid, INIT_PAGE_COUNT);
 		nr_pages++;
 	}
 	return (nr_pages);