linux-kernel - [PATCH 2/5] huge_memory: add huge_zero_page_shrinker

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Message-ID: <20250612105100.59144-3-p.raghav@samsung.com>
Date: Thu, 12 Jun 2025 12:50:57 +0200
From: Pankaj Raghav <p.raghav@...sung.com>
To: Suren Baghdasaryan <surenb@...gle.com>,
	Ryan Roberts <ryan.roberts@....com>,
	Mike Rapoport <rppt@...nel.org>,
	Michal Hocko <mhocko@...e.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Nico Pache <npache@...hat.com>,
	Dev Jain <dev.jain@....com>,
	Baolin Wang <baolin.wang@...ux.alibaba.com>,
	Borislav Petkov <bp@...en8.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H . Peter Anvin" <hpa@...or.com>,
	Vlastimil Babka <vbabka@...e.cz>,
	Zi Yan <ziy@...dia.com>,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	David Hildenbrand <david@...hat.com>,
	Lorenzo Stoakes <lorenzo.stoakes@...cle.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	"Liam R . Howlett" <Liam.Howlett@...cle.com>,
	Jens Axboe <axboe@...nel.dk>
Cc: linux-kernel@...r.kernel.org,
	linux-mm@...ck.org,
	willy@...radead.org,
	x86@...nel.org,
	linux-block@...r.kernel.org,
	linux-fsdevel@...r.kernel.org,
	"Darrick J . Wong" <djwong@...nel.org>,
	mcgrof@...nel.org,
	gost.dev@...sung.com,
	kernel@...kajraghav.com,
	hch@....de,
	Pankaj Raghav <p.raghav@...sung.com>
Subject: [PATCH 2/5] huge_memory: add huge_zero_page_shrinker_(init|exit) function

Add huge_zero_page_shrinker_init() and huge_zero_page_shrinker_exit().
As shrinker will not be needed when static PMD zero page is enabled,
these two functions can be a no-op.

This is a preparation patch for static PMD zero page. No functional
changes.

Signed-off-by: Pankaj Raghav <p.raghav@...sung.com>
---
 mm/huge_memory.c | 38 +++++++++++++++++++++++++++-----------
 1 file changed, 27 insertions(+), 11 deletions(-)

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index d3e66136e41a..101b67ab2eb6 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -289,6 +289,24 @@ static unsigned long shrink_huge_zero_page_scan(struct shrinker *shrink,
 }
 
 static struct shrinker *huge_zero_page_shrinker;
+static int huge_zero_page_shrinker_init(void)
+{
+	huge_zero_page_shrinker = shrinker_alloc(0, "thp-zero");
+	if (!huge_zero_page_shrinker)
+		return -ENOMEM;
+
+	huge_zero_page_shrinker->count_objects = shrink_huge_zero_page_count;
+	huge_zero_page_shrinker->scan_objects = shrink_huge_zero_page_scan;
+	shrinker_register(huge_zero_page_shrinker);
+	return 0;
+}
+
+static void huge_zero_page_shrinker_exit(void)
+{
+	shrinker_free(huge_zero_page_shrinker);
+	return;
+}
+
 
 #ifdef CONFIG_SYSFS
 static ssize_t enabled_show(struct kobject *kobj,
@@ -850,33 +868,31 @@ static inline void hugepage_exit_sysfs(struct kobject *hugepage_kobj)
 
 static int __init thp_shrinker_init(void)
 {
-	huge_zero_page_shrinker = shrinker_alloc(0, "thp-zero");
-	if (!huge_zero_page_shrinker)
-		return -ENOMEM;
+	int ret = 0;
 
 	deferred_split_shrinker = shrinker_alloc(SHRINKER_NUMA_AWARE |
 						 SHRINKER_MEMCG_AWARE |
 						 SHRINKER_NONSLAB,
 						 "thp-deferred_split");
-	if (!deferred_split_shrinker) {
-		shrinker_free(huge_zero_page_shrinker);
+	if (!deferred_split_shrinker)
 		return -ENOMEM;
-	}
-
-	huge_zero_page_shrinker->count_objects = shrink_huge_zero_page_count;
-	huge_zero_page_shrinker->scan_objects = shrink_huge_zero_page_scan;
-	shrinker_register(huge_zero_page_shrinker);
 
 	deferred_split_shrinker->count_objects = deferred_split_count;
 	deferred_split_shrinker->scan_objects = deferred_split_scan;
 	shrinker_register(deferred_split_shrinker);
 
+	ret = huge_zero_page_shrinker_init();
+	if (ret) {
+		shrinker_free(deferred_split_shrinker);
+		return ret;
+	}
+
 	return 0;
 }
 
 static void __init thp_shrinker_exit(void)
 {
-	shrinker_free(huge_zero_page_shrinker);
+	huge_zero_page_shrinker_exit();
 	shrinker_free(deferred_split_shrinker);
 }
 
-- 
2.49.0