From: Breno Leitao <leitao@debian.org>
To: Andrew Morton <akpm@linux-foundation.org>,
David Hildenbrand <david@kernel.org>,
Lorenzo Stoakes <lorenzo.stoakes@oracle.com>,
Zi Yan <ziy@nvidia.com>,
Baolin Wang <baolin.wang@linux.alibaba.com>,
"Liam R. Howlett" <Liam.Howlett@oracle.com>,
Nico Pache <npache@redhat.com>,
Ryan Roberts <ryan.roberts@arm.com>, Dev Jain <dev.jain@arm.com>,
Barry Song <baohua@kernel.org>,
Lance Yang <lance.yang@linux.dev>,
Vlastimil Babka <vbabka@kernel.org>,
Suren Baghdasaryan <surenb@google.com>,
Michal Hocko <mhocko@suse.com>,
Brendan Jackman <jackmanb@google.com>,
Johannes Weiner <hannes@cmpxchg.org>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
usamaarif642@gmail.com, kas@kernel.org, kernel-team@meta.com,
Breno Leitao <leitao@debian.org>
Subject: [PATCH 2/2] mm: thp: avoid calling start_stop_khugepaged() in enabled_store()
Date: Wed, 04 Mar 2026 02:22:34 -0800 [thread overview]
Message-ID: <20260304-thp_logs-v1-2-59038218a253@debian.org> (raw)
In-Reply-To: <20260304-thp_logs-v1-0-59038218a253@debian.org>
Avoid calling start_stop_khugepaged() at the top-level enabled_store()
for /sys/kernel/mm/transparent_hugepage/enabled. Use test_and_set_bit()
and test_and_clear_bit() to detect whether the configuration
actually changed before calling start_stop_khugepaged().
This avoid calling start_stop_khugepaged() unnecessary.
Signed-off-by: Breno Leitao <leitao@debian.org>
---
mm/huge_memory.c | 21 ++++++++++++++-------
1 file changed, 14 insertions(+), 7 deletions(-)
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 9abfb115e9329..b6ed44b6e8c02 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -320,21 +320,28 @@ static ssize_t enabled_store(struct kobject *kobj,
struct kobj_attribute *attr,
const char *buf, size_t count)
{
+ bool changed = false;
ssize_t ret = count;
if (sysfs_streq(buf, "always")) {
- clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags);
- set_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags);
+ changed = test_and_clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
+ &transparent_hugepage_flags);
+ changed |= !test_and_set_bit(TRANSPARENT_HUGEPAGE_FLAG,
+ &transparent_hugepage_flags);
} else if (sysfs_streq(buf, "madvise")) {
- clear_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags);
- set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags);
+ changed = test_and_clear_bit(TRANSPARENT_HUGEPAGE_FLAG,
+ &transparent_hugepage_flags);
+ changed |= !test_and_set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
+ &transparent_hugepage_flags);
} else if (sysfs_streq(buf, "never")) {
- clear_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags);
- clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags);
+ changed = test_and_clear_bit(TRANSPARENT_HUGEPAGE_FLAG,
+ &transparent_hugepage_flags);
+ changed |= test_and_clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
+ &transparent_hugepage_flags);
} else
ret = -EINVAL;
- if (ret > 0) {
+ if (ret > 0 && changed) {
int err = start_stop_khugepaged();
if (err)
ret = err;
--
2.47.3
next prev parent reply other threads:[~2026-03-04 10:23 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-03-04 10:22 [PATCH 0/2] mm: thp: reduce unnecessary start_stop_khugepaged() calls Breno Leitao
2026-03-04 10:22 ` [PATCH 1/2] mm: thp: avoid calling start_stop_khugepaged() in anon_enabled_store() Breno Leitao
2026-03-04 10:22 ` Breno Leitao [this message]
2026-03-04 11:18 ` [PATCH 0/2] mm: thp: reduce unnecessary start_stop_khugepaged() calls Kiryl Shutsemau
2026-03-04 11:53 ` Breno Leitao
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