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mm: replace (20 - PAGE_SHIFT) with common macros for pages<->MB conversion 

Replace repeated (20 - PAGE_SHIFT) calculations with standard macros:
- MB_TO_PAGES(mb)    converts MB to page count
- PAGES_TO_MB(pages) converts pages to MB

No functional change.

[akpm@linux-foundation.org: remove arc's private PAGES_TO_MB, remove its unused PAGES_TO_KB]
[akpm@linux-foundation.org: don't include mm.h due to include file ordering mess]
Link: https://lkml.kernel.org/r/20250718024134.1304745-1-ye.liu@linux.dev
Signed-off-by: Ye Liu <liuye@kylinos.cn>
Acked-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: Dev Jain <dev.jain@arm.com>
Acked-by: David Hildenbrand <david@redhat.com>
Acked-by: Chris Li <chrisl@kernel.org>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Ben Segall <bsegall@google.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Frederic Weisbecker <frederic@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Kairui Song <kasong@tencent.com>
Cc: Kemeng Shi <shikemeng@huaweicloud.com>
Cc: Lai jiangshan <jiangshanlai@gmail.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Mariano Pache <npache@redhat.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Mel Gorman <mgorman <mgorman@suse.de>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: "Paul E . McKenney" <paulmck@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: "Uladzislau Rezki (Sony)" <urezki@gmail.com>
Cc: Valentin Schneider <vschneid@redhat.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Ye Liu 2025-07-18 10:41:32 +08:00 committed by Andrew Morton
parent 849d5cff4d
commit 79e1c24285
7 changed files with 15 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
arch/arc/include/asm/arcregs.h
View File

@ -151,9 +151,6 @@
/* Helpers */
#define TO_KB(bytes) ((bytes) >> 10)
#define TO_MB(bytes) (TO_KB(bytes) >> 10)
#define PAGES_TO_KB(n_pages) ((n_pages) << (PAGE_SHIFT - 10))
#define PAGES_TO_MB(n_pages) (PAGES_TO_KB(n_pages) >> 10)
/*
***************************************************************

9
include/linux/mm.h
View File

@ -69,6 +69,15 @@ static inline void totalram_pages_add(long count)
extern void * high_memory;
/*
* Convert between pages and MB
* 20 is the shift for 1MB (2^20 = 1MB)
* PAGE_SHIFT is the shift for page size (e.g., 12 for 4KB pages)
* So (20 - PAGE_SHIFT) converts between pages and MB
*/
#define PAGES_TO_MB(pages) ((pages) >> (20 - PAGE_SHIFT))
#define MB_TO_PAGES(mb) ((mb) << (20 - PAGE_SHIFT))
#ifdef CONFIG_SYSCTL
extern int sysctl_legacy_va_layout;
#else

2
kernel/rcu/rcuscale.c
View File

@ -796,7 +796,7 @@ kfree_scale_thread(void *arg)
pr_alert("Total time taken by all kfree'ers: %llu ns, loops: %d, batches: %ld, memory footprint: %lldMB\n",
(unsigned long long)(end_time - start_time), kfree_loops,
rcuscale_seq_diff(b_rcu_gp_test_finished, b_rcu_gp_test_started),
(mem_begin - mem_during) >> (20 - PAGE_SHIFT));
PAGES_TO_MB(mem_begin - mem_during));
if (shutdown) {
smp_mb(); /* Assign before wake. */

5
kernel/sched/fair.c
View File

@ -1495,7 +1495,7 @@ static unsigned int task_nr_scan_windows(struct task_struct *p)
* by the PTE scanner and NUMA hinting faults should be trapped based
* on resident pages
*/
nr_scan_pages = sysctl_numa_balancing_scan_size << (20 - PAGE_SHIFT);
nr_scan_pages = MB_TO_PAGES(sysctl_numa_balancing_scan_size);
rss = get_mm_rss(p->mm);
if (!rss)
rss = nr_scan_pages;
@ -1934,8 +1934,7 @@ bool should_numa_migrate_memory(struct task_struct *p, struct folio *folio,
}
def_th = sysctl_numa_balancing_hot_threshold;
rate_limit = sysctl_numa_balancing_promote_rate_limit << \
(20 - PAGE_SHIFT);
rate_limit = MB_TO_PAGES(sysctl_numa_balancing_promote_rate_limit);
numa_promotion_adjust_threshold(pgdat, rate_limit, def_th);
th = pgdat->nbp_threshold ? : def_th;

2
mm/backing-dev.c
View File

@ -510,7 +510,7 @@ static void wb_update_bandwidth_workfn(struct work_struct *work)
/*
* Initial write bandwidth: 100 MB/s
*/
#define INIT_BW (100 << (20 - PAGE_SHIFT))
#define INIT_BW MB_TO_PAGES(100)
static int wb_init(struct bdi_writeback *wb, struct backing_dev_info *bdi,
gfp_t gfp)

2
mm/huge_memory.c
View File

@ -911,7 +911,7 @@ static int __init hugepage_init(void)
* where the extra memory used could hurt more than TLB overhead
* is likely to save. The admin can still enable it through /sys.
*/
if (totalram_pages() < (512 << (20 - PAGE_SHIFT))) {
if (totalram_pages() < MB_TO_PAGES(512)) {
transparent_hugepage_flags = 0;
return 0;
}

2
mm/swap.c
View File

@ -1096,7 +1096,7 @@ static const struct ctl_table swap_sysctl_table[] = {
*/
void __init swap_setup(void)
{
unsigned long megs = totalram_pages() >> (20 - PAGE_SHIFT);
unsigned long megs = PAGES_TO_MB(totalram_pages());
/* Use a smaller cluster for small-memory machines */
if (megs < 16)