[PATCH 1/2] Docs/ABI: document transparent_hugepage/shrink_underused
From: Song Hu
Date: Wed Aug 12 2026 - 04:12:37 EST
The shrink_underused knob was added in commit 81d3ff3c6f76 ("mm: add
sysfs entry to disable splitting underused THPs") but is missing from
Documentation/ABI/testing/sysfs-kernel-mm-transparent-hugepage, although
transhuge.rst already documents it. Add the ABI entry.
Signed-off-by: Song Hu <husong@xxxxxxxxxx>
---
.../ABI/testing/sysfs-kernel-mm-transparent-hugepage | 10 ++++++++++
1 file changed, 10 insertions(+)
diff --git a/Documentation/ABI/testing/sysfs-kernel-mm-transparent-hugepage b/Documentation/ABI/testing/sysfs-kernel-mm-transparent-hugepage
index 7bfbb9cc2c11..bbdfae2c0caa 100644
--- a/Documentation/ABI/testing/sysfs-kernel-mm-transparent-hugepage
+++ b/Documentation/ABI/testing/sysfs-kernel-mm-transparent-hugepage
@@ -10,9 +10,19 @@ Description:
- hpage_pmd_size
- khugepaged
- shmem_enabled
+ - shrink_underused
- use_zero_page
- subdirectories of the form hugepages-<size>kB, where <size>
is the page size of the hugepages supported by the kernel/CPU
combination.
See Documentation/admin-guide/mm/transhuge.rst for details.
+
+What: /sys/kernel/mm/transparent_hugepage/shrink_underused
+Date: Sep 2024
+Contact: Linux memory management mailing list <linux-mm@xxxxxxxxx>
+Description: Reading and writing this file controls whether khugepaged
+ splits underused transparent huge pages (THPs) under memory
+ pressure. A THP is considered underused when its number of
+ zero-filled pages is above max_ptes_none. Enabled by default;
+ writing 0 disables the splitting and 1 enables it.
--
2.43.0