* [PATCH v5 1/2] mm: allow optional initialization of page count and PG_reserved flag
2023-09-29 17:00 [PATCH v5 0/2] mm: Don't init and clear page count when MEMINIT_EARLY Yajun Deng
@ 2023-09-29 17:00 ` Yajun Deng
2023-09-29 17:00 ` [PATCH v5 2/2] mm: Init page count in reserve_bootmem_region when MEMINIT_EARLY Yajun Deng
1 sibling, 0 replies; 3+ messages in thread
From: Yajun Deng @ 2023-09-29 17:00 UTC (permalink / raw)
To: akpm, rppt
Cc: mike.kravetz, muchun.song, willy, david, linux-mm, linux-kernel,
Yajun Deng
__init_single_page() unconditionally resets page count which is
unnecessary for reserved pages.
To allow skipping page count initialization and marking a page reserved
in one go add flags parameter to __init_single_page().
No functional changes.
Signed-off-by: Yajun Deng <yajun.deng@linux.dev>
---
v5: change the subject and commit.
v4: remove the changes of __init_zone_device_page().
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 | 24 +++++++++++++-----------
3 files changed, 21 insertions(+), 13 deletions(-)
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 32dbb4f82470..9c22297d9c57 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -3064,7 +3064,7 @@ 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..536bbaa11be1 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -1209,8 +1209,14 @@ struct vma_prepare {
struct vm_area_struct *remove2;
};
+enum page_init_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 page_init_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..0549e7c3d588 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 page_init_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);
@@ -967,9 +971,6 @@ static void __ref __init_zone_device_page(struct page *page, unsigned long pfn,
unsigned long zone_idx, int nid,
struct dev_pagemap *pgmap)
{
-
- __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 +978,8 @@ 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,
+ INIT_PAGE_COUNT | INIT_PAGE_RESERVED);
/*
* ZONE_DEVICE pages union ->lru with a ->pgmap back pointer
@@ -2058,7 +2060,7 @@ 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);
--
2.25.1
^ permalink raw reply [flat|nested] 3+ messages in thread* [PATCH v5 2/2] mm: Init page count in reserve_bootmem_region when MEMINIT_EARLY
2023-09-29 17:00 [PATCH v5 0/2] mm: Don't init and clear page count when MEMINIT_EARLY Yajun Deng
2023-09-29 17:00 ` [PATCH v5 1/2] mm: allow optional initialization of page count and PG_reserved flag Yajun Deng
@ 2023-09-29 17:00 ` Yajun Deng
1 sibling, 0 replies; 3+ messages in thread
From: Yajun Deng @ 2023-09-29 17:00 UTC (permalink / raw)
To: akpm, rppt
Cc: mike.kravetz, muchun.song, willy, david, linux-mm, linux-kernel,
Yajun Deng
memmap_init_range() would init page count of all pages, but the free
pages count would be reset in __free_pages_core(). There are opposite
operations. It's unnecessary and time-consuming when it's MEMINIT_EARLY
context.
Init page count in reserve_bootmem_region when in MEMINIT_EARLY context,
and check the page count before reset it.
At the same time, the INIT_LIST_HEAD in reserve_bootmem_region isn't
need, as it already done in __init_single_page.
The following data was tested on an x86 machine with 190GB of RAM.
before:
free_low_memory_core_early() 341ms
after:
free_low_memory_core_early() 285ms
Signed-off-by: Yajun Deng <yajun.deng@linux.dev>
---
v5: add flags in memmap_init_range.
v4: same with v2.
v3: same with v2.
v2: check page count instead of check context before reset it.
v1: https://lore.kernel.org/all/20230922070923.355656-1-yajun.deng@linux.dev/
---
mm/mm_init.c | 20 +++++++++++++++-----
mm/page_alloc.c | 20 ++++++++++++--------
2 files changed, 27 insertions(+), 13 deletions(-)
diff --git a/mm/mm_init.c b/mm/mm_init.c
index 0549e7c3d588..f84f1ede57c6 100644
--- a/mm/mm_init.c
+++ b/mm/mm_init.c
@@ -718,7 +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_PAGE_COUNT);
+ __init_single_page(pfn_to_page(pfn), pfn, zid, nid, 0);
}
#else
static inline void pgdat_set_deferred_range(pg_data_t *pgdat) {}
@@ -756,8 +756,11 @@ void __meminit reserve_bootmem_region(phys_addr_t start,
init_reserved_page(start_pfn, nid);
- /* Avoid false-positive PageTail() */
- INIT_LIST_HEAD(&page->lru);
+ /*
+ * We didn't init page count in memmap_init_range when
+ * MEMINIT_EARLY, so it must init page count here.
+ */
+ init_page_count(page);
/*
* no need for atomic set_bit because the struct
@@ -850,6 +853,7 @@ void __meminit memmap_init_range(unsigned long size, int nid, unsigned long zone
struct vmem_altmap *altmap, int migratetype)
{
unsigned long pfn, end_pfn = start_pfn + size;
+ enum page_init_flags flags = 0;
struct page *page;
if (highest_memmap_pfn < end_pfn - 1)
@@ -888,9 +892,15 @@ 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_PAGE_COUNT);
+
+ /* If the context is MEMINIT_EARLY, we will init page count and
+ * mark page reserved in reserve_bootmem_region, the free region
+ * wouldn't have page count and we will check the pages count
+ * in __free_pages_core.
+ */
if (context == MEMINIT_HOTPLUG)
- __SetPageReserved(page);
+ flags = INIT_PAGE_COUNT | INIT_PAGE_RESERVED;
+ __init_single_page(page, pfn, zone, nid, flags);
/*
* Usually, we want to mark the pageblock MIGRATE_MOVABLE,
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 7df77b58a961..bc68b5452d01 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1289,18 +1289,22 @@ void __free_pages_core(struct page *page, unsigned int order)
unsigned int loop;
/*
- * When initializing the memmap, __init_single_page() sets the refcount
- * of all pages to 1 ("allocated"/"not free"). We have to set the
- * refcount of all involved pages to 0.
+ * When initializing the memmap, memmap_init_range sets the refcount
+ * of all pages to 1 ("reserved" and "free") in hotplug context. We
+ * have to set the refcount of all involved pages to 0. Otherwise,
+ * we don't do it, as reserve_bootmem_region only set the refcount on
+ * reserve region ("reserved") in early context.
*/
- prefetchw(p);
- for (loop = 0; loop < (nr_pages - 1); loop++, p++) {
- prefetchw(p + 1);
+ if (page_count(page)) {
+ prefetchw(p);
+ for (loop = 0; loop < (nr_pages - 1); loop++, p++) {
+ prefetchw(p + 1);
+ __ClearPageReserved(p);
+ set_page_count(p, 0);
+ }
__ClearPageReserved(p);
set_page_count(p, 0);
}
- __ClearPageReserved(p);
- set_page_count(p, 0);
atomic_long_add(nr_pages, &page_zone(page)->managed_pages);
--
2.25.1
^ permalink raw reply [flat|nested] 3+ messages in thread