From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-181.mta1.migadu.com (out-181.mta1.migadu.com [95.215.58.181]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E273D3597A for ; Fri, 18 Jul 2025 02:42:13 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.181 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752806537; cv=none; b=E7/3EutPkt8XYbqTOAbBwWsxWM2tMlqE9k0+tlK0ZO4/4TgnAxrfJ/R6pwr74iDBCnW+p/UZiE9NES8J0P0Pa8Amcd7dCerpJypOUOPw1Snbe5Y7CRLws1kh97OM3QJkVVWLe/+EijNfqEYZFqfFEtGF3PBV7WMYa0dMM9688nk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752806537; c=relaxed/simple; bh=1q9nTy6bjkYnpdPdD5bIaq1harlEkcTnLyzp577t9Xs=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=HTQVz96tlP3Z1Aba6JYEg42NSv2XvcdVeWsKFeIvpAFK897SDB770mSn3EPyKSmJE+tZ5cCQxDbF2ksEEuuRI+ljcbMBrYi8Yq5RhLG+FZsdzLZNaKQosibn/01RJKlUrAulY8DcA13NuD1nqBmShjN3OIDhr6+ygYpimq8ZdGA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=C+z0v/Bt; arc=none smtp.client-ip=95.215.58.181 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="C+z0v/Bt" X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1752806531; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=165mTwuoOHXsCCkCN512tFxf4UxYV8qKAC9hxkL+/Lk=; b=C+z0v/BtEiiH9bIvE3RyS1HXloAmCIbAStbntjBf2mzpaCnw8iYPm5/ned/zGKD+pvLvtb 0Q4d6uYcc7MHKk3uuNZ5T1hA/mtaOkIqc1xQhfbN62oCCmiUeuMA2fvAkJjqtY6Jx0EbXK 2itEeFIJViPwTpLZiavmpOzp9/s1548= From: Ye Liu To: Andrew Morton , David Hildenbrand , Davidlohr Bueso , "Paul E. McKenney" , Josh Triplett , Frederic Weisbecker , Neeraj Upadhyay , Joel Fernandes , Boqun Feng , Uladzislau Rezki , Ingo Molnar , Peter Zijlstra , Juri Lelli , Vincent Guittot , Lorenzo Stoakes Cc: Ye Liu , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Steven Rostedt , Mathieu Desnoyers , Lai Jiangshan , Zqiang , Dietmar Eggemann , Ben Segall , Mel Gorman , Valentin Schneider , Zi Yan , Baolin Wang , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Kemeng Shi , Kairui Song , Nhat Pham , Baoquan He , Chris Li , linux-mm@kvack.org, linux-kernel@vger.kernel.org, rcu@vger.kernel.org Subject: [PATCH] mm: Replace (20 - PAGE_SHIFT) with common macros for pages<->MB conversion Date: Fri, 18 Jul 2025 10:41:32 +0800 Message-ID: <20250718024134.1304745-1-ye.liu@linux.dev> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT From: Ye Liu 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. Signed-off-by: Ye Liu --- include/linux/mm.h | 9 +++++++++ kernel/rcu/rcuscale.c | 2 +- kernel/sched/fair.c | 5 ++--- mm/backing-dev.c | 2 +- mm/huge_memory.c | 2 +- mm/swap.c | 2 +- 6 files changed, 15 insertions(+), 7 deletions(-) diff --git a/include/linux/mm.h b/include/linux/mm.h index 957acde6ae62..0c1b2c074142 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -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 diff --git a/kernel/rcu/rcuscale.c b/kernel/rcu/rcuscale.c index b521d0455992..7484d8ad5767 100644 --- a/kernel/rcu/rcuscale.c +++ b/kernel/rcu/rcuscale.c @@ -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. */ diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index b9b4bbbf0af6..ae1d9a7ef202 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -1489,7 +1489,7 @@ 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; @@ -1926,8 +1926,7 @@ 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; diff --git a/mm/backing-dev.c b/mm/backing-dev.c index 783904d8c5ef..e4d578e6121c 100644 --- a/mm/backing-dev.c +++ b/mm/backing-dev.c @@ -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) diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 389620c65a5f..dcc33d9c300f 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -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; } diff --git a/mm/swap.c b/mm/swap.c index 3632dd061beb..cb164f9ef9e3 100644 --- a/mm/swap.c +++ b/mm/swap.c @@ -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) -- 2.43.0