[PATCH v2] mm: introduce PAGEFLAGS_MASK to replace ((1UL << NR_PAGEFLAGS) - 1)

Muchun Song
2021-08-19T15:07:29Z

Instead of hard-coding ((1UL << NR_PAGEFLAGS) - 1) everywhere, introducing
PAGEFLAGS_MASK to make the code clear to get the page flags.

Signed-off-by: Muchun Song <songmuchun@bytedance.com>
---
Change log in v2:
1. Revert PAGEFLAGS_MASK

include/linux/page-flags.h | 4 +++-
include/trace/events/page_ref.h | 4 ++--
lib/test_printf.c | 2 +-
lib/vsprintf.c | 2 +-
4 files changed, 7 insertions(+), 5 deletions(-)

diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
index 54c4af35c628..8e1d97d8f3bd 100644
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -180,6 +180,8 @@ enum pageflags {
PG_reported = PG_uptodate,
};

+#define PAGEFLAGS_MASK ((1UL << NR_PAGEFLAGS) - 1)
+
#ifndef __GENERATING_BOUNDS_H

static inline unsigned long _compound_head(const struct page *page)
@@ -975,7 +977,7 @@ static inline void ClearPageSlabPfmemalloc(struct page *page)
* alloc-free cycle to prevent from reusing the page.
*/
#define PAGE_FLAGS_CHECK_AT_PREP \
- (((1UL << NR_PAGEFLAGS) - 1) & ~__PG_HWPOISON)
+ (PAGEFLAGS_MASK & ~__PG_HWPOISON)

#define PAGE_FLAGS_PRIVATE \
(1UL << PG_private | 1UL << PG_private_2)
diff --git a/include/trace/events/page_ref.h b/include/trace/events/page_ref.h
index 5d2ea93956ce..8a99c1cd417b 100644
--- a/include/trace/events/page_ref.h
+++ b/include/trace/events/page_ref.h
@@ -38,7 +38,7 @@ DECLARE_EVENT_CLASS(page_ref_mod_template,

TP_printk("pfn=0x%lx flags=%s count=%d mapcount=%d mapping=%p mt=%d val=%d",
__entry->pfn,
- show_page_flags(__entry->flags & ((1UL << NR_PAGEFLAGS) - 1)),
+ show_page_flags(__entry->flags & PAGEFLAGS_MASK),
__entry->count,
__entry->mapcount, __entry->mapping, __entry->mt,
__entry->val)
@@ -88,7 +88,7 @@ DECLARE_EVENT_CLASS(page_ref_mod_and_test_template,

TP_printk("pfn=0x%lx flags=%s count=%d mapcount=%d mapping=%p mt=%d val=%d ret=%d",
__entry->pfn,
- show_page_flags(__entry->flags & ((1UL << NR_PAGEFLAGS) - 1)),
+ show_page_flags(__entry->flags & PAGEFLAGS_MASK),
__entry->count,
__entry->mapcount, __entry->mapping, __entry->mt,
__entry->val, __entry->ret)
diff --git a/lib/test_printf.c b/lib/test_printf.c
index 8ac71aee46af..ec69953cf80c 100644
--- a/lib/test_printf.c
+++ b/lib/test_printf.c
@@ -614,7 +614,7 @@ page_flags_test(int section, int node, int zone, int last_cpupid,
bool append = false;
int i;

- flags &= BIT(NR_PAGEFLAGS) - 1;
+ flags &= PAGEFLAGS_MASK;
if (flags) {
page_flags |= flags;
snprintf(cmp_buf + size, BUF_SIZE - size, "%s", name);
diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index dd006adfe853..42ad16327c75 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -2019,7 +2019,7 @@ static const struct page_flags_fields pff[] = {
static
char *format_page_flags(char *buf, char *end, unsigned long flags)
{
- unsigned long main_flags = flags & (BIT(NR_PAGEFLAGS) - 1);
+ unsigned long main_flags = flags & PAGEFLAGS_MASK;
bool append = false;
int i;

--
2.11.0