[RFC PATCH v2 03/12] mm: replace MAX_ORDER when it is used to indicate max physical contiguity.
From: Zi Yan
Date: Thu Aug 11 2022 - 19:17:06 EST
From: Zi Yan <ziy@xxxxxxxxxx>
MAX_ORDER is limited at a memory section size, thus widely used as
a variable to indicate maximum physically contiguous page size. But this
limitation is no longer necessary as kernel only supports sparse memory
model. Add a new variable MAX_PHYS_CONTIG_ORDER to replace such uses of
MAX_ORDER.
Signed-off-by: Zi Yan <ziy@xxxxxxxxxx>
---
Documentation/admin-guide/kernel-parameters.txt | 2 +-
arch/sparc/mm/tsb.c | 4 ++--
arch/um/kernel/um_arch.c | 4 ++--
include/linux/pageblock-flags.h | 12 ++++++++++++
kernel/dma/pool.c | 8 ++++----
mm/hugetlb.c | 2 +-
mm/internal.h | 8 ++++----
mm/memory.c | 4 ++--
mm/memory_hotplug.c | 6 +++---
mm/page_isolation.c | 2 +-
mm/page_reporting.c | 4 ++--
11 files changed, 34 insertions(+), 22 deletions(-)
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index ff33971e1630..ec519225b671 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -3899,7 +3899,7 @@
[KNL] Minimal page reporting order
Format: <integer>
Adjust the minimal page reporting order. The page
- reporting is disabled when it exceeds MAX_ORDER.
+ reporting is disabled when it exceeds MAX_PHYS_CONTIG_ORDER.
panic= [KNL] Kernel behaviour on panic: delay <timeout>
timeout > 0: seconds before rebooting
diff --git a/arch/sparc/mm/tsb.c b/arch/sparc/mm/tsb.c
index 912205787161..15c31d050dab 100644
--- a/arch/sparc/mm/tsb.c
+++ b/arch/sparc/mm/tsb.c
@@ -402,8 +402,8 @@ void tsb_grow(struct mm_struct *mm, unsigned long tsb_index, unsigned long rss)
unsigned long new_rss_limit;
gfp_t gfp_flags;
- if (max_tsb_size > (PAGE_SIZE << MAX_ORDER))
- max_tsb_size = (PAGE_SIZE << MAX_ORDER);
+ if (max_tsb_size > (PAGE_SIZE << MAX_PHYS_CONTIG_ORDER))
+ max_tsb_size = (PAGE_SIZE << MAX_PHYS_CONTIG_ORDER);
new_cache_index = 0;
for (new_size = 8192; new_size < max_tsb_size; new_size <<= 1UL) {
diff --git a/arch/um/kernel/um_arch.c b/arch/um/kernel/um_arch.c
index e0de60e503b9..52a474f4f1c7 100644
--- a/arch/um/kernel/um_arch.c
+++ b/arch/um/kernel/um_arch.c
@@ -368,10 +368,10 @@ int __init linux_main(int argc, char **argv)
max_physmem = TASK_SIZE - uml_physmem - iomem_size - MIN_VMALLOC;
/*
- * Zones have to begin on a 1 << MAX_ORDER page boundary,
+ * Zones have to begin on a 1 << MAX_PHYS_CONTIG_ORDER page boundary,
* so this makes sure that's true for highmem
*/
- max_physmem &= ~((1 << (PAGE_SHIFT + MAX_ORDER)) - 1);
+ max_physmem &= ~((1 << (PAGE_SHIFT + MAX_PHYS_CONTIG_ORDER)) - 1);
if (physmem_size + iomem_size > max_physmem) {
highmem = physmem_size + iomem_size - max_physmem;
physmem_size -= highmem;
diff --git a/include/linux/pageblock-flags.h b/include/linux/pageblock-flags.h
index 940efcffd374..358b871b07ca 100644
--- a/include/linux/pageblock-flags.h
+++ b/include/linux/pageblock-flags.h
@@ -54,6 +54,18 @@ extern unsigned int pageblock_order;
#define pageblock_nr_pages (1UL << pageblock_order)
+/*
+ * memory section is only defined in sparsemem and in flatmem, pages are always
+ * physically contiguous, but we use MAX_ORDER since all users assume so.
+ */
+#ifdef CONFIG_FLATMEM
+#define MAX_PHYS_CONTIG_ORDER MAX_ORDER
+#else /* SPARSEMEM */
+#define MAX_PHYS_CONTIG_ORDER (min(PFN_SECTION_SHIFT, MAX_ORDER))
+#endif /* CONFIG_FLATMEM */
+
+#define MAX_PHYS_CONTIG_NR_PAGES (1UL << MAX_PHYS_CONTIG_ORDER)
+
/* Forward declaration */
struct page;
diff --git a/kernel/dma/pool.c b/kernel/dma/pool.c
index e20f168a34c7..b10f1dd52871 100644
--- a/kernel/dma/pool.c
+++ b/kernel/dma/pool.c
@@ -84,8 +84,8 @@ static int atomic_pool_expand(struct gen_pool *pool, size_t pool_size,
void *addr;
int ret = -ENOMEM;
- /* Cannot allocate larger than MAX_ORDER */
- order = min(get_order(pool_size), MAX_ORDER);
+ /* Cannot allocate larger than MAX_PHYS_CONTIG_ORDER */
+ order = min(get_order(pool_size), MAX_PHYS_CONTIG_ORDER);
do {
pool_size = 1 << (PAGE_SHIFT + order);
@@ -190,11 +190,11 @@ static int __init dma_atomic_pool_init(void)
/*
* If coherent_pool was not used on the command line, default the pool
- * sizes to 128KB per 1GB of memory, min 128KB, max MAX_ORDER.
+ * sizes to 128KB per 1GB of memory, min 128KB, max MAX_PHYS_CONTIG_ORDER.
*/
if (!atomic_pool_size) {
unsigned long pages = totalram_pages() / (SZ_1G / SZ_128K);
- pages = min_t(unsigned long, pages, MAX_ORDER_NR_PAGES);
+ pages = min_t(unsigned long, pages, MAX_PHYS_CONTIG_NR_PAGES);
atomic_pool_size = max_t(size_t, pages << PAGE_SHIFT, SZ_128K);
}
INIT_WORK(&atomic_pool_work, atomic_pool_work_fn);
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 15ff582687a3..36eedeed1b22 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -1903,7 +1903,7 @@ pgoff_t hugetlb_basepage_index(struct page *page)
pgoff_t index = page_index(page_head);
unsigned long compound_idx;
- if (compound_order(page_head) > MAX_ORDER)
+ if (compound_order(page_head) > MAX_PHYS_CONTIG_ORDER)
compound_idx = page_to_pfn(page) - page_to_pfn(page_head);
else
compound_idx = page - page_head;
diff --git a/mm/internal.h b/mm/internal.h
index 4df67b6b8cce..1433e3a6fdd0 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -302,7 +302,7 @@ static inline bool page_is_buddy(struct page *page, struct page *buddy,
* satisfies the following equation:
* P = B & ~(1 << O)
*
- * Assumption: *_mem_map is contiguous at least up to MAX_ORDER
+ * Assumption: *_mem_map is contiguous at least up to MAX_PHYS_CONTIG_ORDER
*/
static inline unsigned long
__find_buddy_pfn(unsigned long page_pfn, unsigned int order)
@@ -642,11 +642,11 @@ static inline void vunmap_range_noflush(unsigned long start, unsigned long end)
/*
* Return the mem_map entry representing the 'offset' subpage within
* the maximally aligned gigantic page 'base'. Handle any discontiguity
- * in the mem_map at MAX_ORDER_NR_PAGES boundaries.
+ * in the mem_map at MAX_PHYS_CONTIG_NR_PAGES boundaries.
*/
static inline struct page *mem_map_offset(struct page *base, int offset)
{
- if (unlikely(offset >= MAX_ORDER_NR_PAGES))
+ if (unlikely(offset >= MAX_PHYS_CONTIG_NR_PAGES))
return nth_page(base, offset);
return base + offset;
}
@@ -658,7 +658,7 @@ static inline struct page *mem_map_offset(struct page *base, int offset)
static inline struct page *mem_map_next(struct page *iter,
struct page *base, int offset)
{
- if (unlikely((offset & (MAX_ORDER_NR_PAGES - 1)) == 0)) {
+ if (unlikely((offset & (MAX_PHYS_CONTIG_NR_PAGES - 1)) == 0)) {
unsigned long pfn = page_to_pfn(base) + offset;
if (!pfn_valid(pfn))
return NULL;
diff --git a/mm/memory.c b/mm/memory.c
index bd8e7e79be99..3b82945aaa3d 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -5660,7 +5660,7 @@ void clear_huge_page(struct page *page,
unsigned long addr = addr_hint &
~(((unsigned long)pages_per_huge_page << PAGE_SHIFT) - 1);
- if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) {
+ if (unlikely(pages_per_huge_page > MAX_PHYS_CONTIG_NR_PAGES)) {
clear_gigantic_page(page, addr, pages_per_huge_page);
return;
}
@@ -5713,7 +5713,7 @@ void copy_user_huge_page(struct page *dst, struct page *src,
.vma = vma,
};
- if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) {
+ if (unlikely(pages_per_huge_page > MAX_PHYS_CONTIG_NR_PAGES)) {
copy_user_gigantic_page(dst, src, addr, vma,
pages_per_huge_page);
return;
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 5540499007ae..8930823e5067 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -596,16 +596,16 @@ static void online_pages_range(unsigned long start_pfn, unsigned long nr_pages)
unsigned long pfn;
/*
- * Online the pages in MAX_ORDER aligned chunks. The callback might
+ * Online the pages in MAX_PHYS_CONTIG_ORDER aligned chunks. The callback might
* decide to not expose all pages to the buddy (e.g., expose them
* later). We account all pages as being online and belonging to this
* zone ("present").
* When using memmap_on_memory, the range might not be aligned to
- * MAX_ORDER_NR_PAGES - 1, but pageblock aligned. __ffs() will detect
+ * MAX_PHYS_CONTIG_NR_PAGES - 1, but pageblock aligned. __ffs() will detect
* this and the first chunk to online will be pageblock_nr_pages.
*/
for (pfn = start_pfn; pfn < end_pfn;) {
- int order = min_t(unsigned long, MAX_ORDER, __ffs(pfn));
+ int order = min_t(unsigned long, MAX_PHYS_CONTIG_ORDER, __ffs(pfn));
(*online_page_callback)(pfn_to_page(pfn), order);
pfn += (1UL << order);
diff --git a/mm/page_isolation.c b/mm/page_isolation.c
index 8d33120a81b2..801835f91c44 100644
--- a/mm/page_isolation.c
+++ b/mm/page_isolation.c
@@ -226,7 +226,7 @@ static void unset_migratetype_isolate(struct page *page, int migratetype)
*/
if (PageBuddy(page)) {
order = buddy_order(page);
- if (order >= pageblock_order && order <= MAX_ORDER) {
+ if (order >= pageblock_order && order <= MAX_PHYS_CONTIG_ORDER) {
buddy = find_buddy_page_pfn(page, page_to_pfn(page),
order, NULL);
if (buddy && !is_migrate_isolate_page(buddy)) {
diff --git a/mm/page_reporting.c b/mm/page_reporting.c
index d52a55bca6d5..b48d6ad82998 100644
--- a/mm/page_reporting.c
+++ b/mm/page_reporting.c
@@ -11,7 +11,7 @@
#include "page_reporting.h"
#include "internal.h"
-unsigned int page_reporting_order = MAX_ORDER + 1;
+unsigned int page_reporting_order = MAX_PHYS_CONTIG_ORDER + 1;
module_param(page_reporting_order, uint, 0644);
MODULE_PARM_DESC(page_reporting_order, "Set page reporting order");
@@ -244,7 +244,7 @@ page_reporting_process_zone(struct page_reporting_dev_info *prdev,
return err;
/* Process each free list starting from lowest order/mt */
- for (order = page_reporting_order; order <= MAX_ORDER; order++) {
+ for (order = page_reporting_order; order <= MAX_PHYS_CONTIG_ORDER; order++) {
for (mt = 0; mt < MIGRATE_TYPES; mt++) {
/* We do not pull pages from the isolate free list */
if (is_migrate_isolate(mt))
--
2.35.1