From: Nico Pache <npache@redhat.com>
Date: Wed, 25 Mar 2026 11:40:20 +0000 (-0600)
Subject: mm/khugepaged: define KHUGEPAGED_MAX_PTES_LIMIT as HPAGE_PMD_NR - 1
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=36da8a88fd3b519fd31b2f31bbea1b189df6cd8c;p=thirdparty%2Fkernel%2Flinux.git

mm/khugepaged: define KHUGEPAGED_MAX_PTES_LIMIT as HPAGE_PMD_NR - 1

The value (HPAGE_PMD_NR - 1) is used often in the khugepaged code to
signify the limit of the max_ptes_* values.  Add a define for this to
increase code readability and reuse.

Link: https://lkml.kernel.org/r/20260325114022.444081-4-npache@redhat.com
Signed-off-by: Nico Pache <npache@redhat.com>
Acked-by: Pedro Falcato <pfalcato@suse.de>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Suggested-by: Lorenzo Stoakes (Oracle) <ljs@kernel.org>
Reviewed-by: Lorenzo Stoakes (Oracle) <ljs@kernel.org>
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Brendan Jackman <jackmanb@google.com>
Cc: Byungchul Park <byungchul@sk.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Gregory Price <gourry@gourry.net>
Cc: "Huang, Ying" <ying.huang@linux.alibaba.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jann Horn <jannh@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Joshua Hahn <joshua.hahnjy@gmail.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Matthew Brost <matthew.brost@intel.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Nanyong Sun <sunnanyong@huawei.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Rafael Aquini <raquini@redhat.com>
Cc: Rakie Kim <rakie.kim@sk.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Shivank Garg <shivankg@amd.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Takashi Iwai (SUSE) <tiwai@suse.de>
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Cc: Usama Arif <usamaarif642@gmail.com>
Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: Will Deacon <will@kernel.org>
Cc: Yang Shi <yang@os.amperecomputing.com>
Cc: Zach O'Keefe <zokeefe@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index c6a5d9d1f252d..322964d07c1d6 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -89,6 +89,7 @@ static DECLARE_WAIT_QUEUE_HEAD(khugepaged_wait);
  *
  * Note that these are only respected if collapse was initiated by khugepaged.
  */
+#define KHUGEPAGED_MAX_PTES_LIMIT (HPAGE_PMD_NR - 1)
 unsigned int khugepaged_max_ptes_none __read_mostly;
 static unsigned int khugepaged_max_ptes_swap __read_mostly;
 static unsigned int khugepaged_max_ptes_shared __read_mostly;
@@ -259,7 +260,7 @@ static ssize_t max_ptes_none_store(struct kobject *kobj,
 	unsigned long max_ptes_none;
 
 	err = kstrtoul(buf, 10, &max_ptes_none);
-	if (err || max_ptes_none > HPAGE_PMD_NR - 1)
+	if (err || max_ptes_none > KHUGEPAGED_MAX_PTES_LIMIT)
 		return -EINVAL;
 
 	khugepaged_max_ptes_none = max_ptes_none;
@@ -284,7 +285,7 @@ static ssize_t max_ptes_swap_store(struct kobject *kobj,
 	unsigned long max_ptes_swap;
 
 	err  = kstrtoul(buf, 10, &max_ptes_swap);
-	if (err || max_ptes_swap > HPAGE_PMD_NR - 1)
+	if (err || max_ptes_swap > KHUGEPAGED_MAX_PTES_LIMIT)
 		return -EINVAL;
 
 	khugepaged_max_ptes_swap = max_ptes_swap;
@@ -310,7 +311,7 @@ static ssize_t max_ptes_shared_store(struct kobject *kobj,
 	unsigned long max_ptes_shared;
 
 	err  = kstrtoul(buf, 10, &max_ptes_shared);
-	if (err || max_ptes_shared > HPAGE_PMD_NR - 1)
+	if (err || max_ptes_shared > KHUGEPAGED_MAX_PTES_LIMIT)
 		return -EINVAL;
 
 	khugepaged_max_ptes_shared = max_ptes_shared;
@@ -382,7 +383,7 @@ int __init khugepaged_init(void)
 		return -ENOMEM;
 
 	khugepaged_pages_to_scan = HPAGE_PMD_NR * 8;
-	khugepaged_max_ptes_none = HPAGE_PMD_NR - 1;
+	khugepaged_max_ptes_none = KHUGEPAGED_MAX_PTES_LIMIT;
 	khugepaged_max_ptes_swap = HPAGE_PMD_NR / 8;
 	khugepaged_max_ptes_shared = HPAGE_PMD_NR / 2;