From: Wei Yang <richard.weiyang@gmail.com>
Date: Fri, 14 Nov 2025 03:00:26 +0000 (+0000)
Subject: mm/khugepaged: remove redundant clearing of struct collapse_control
X-Git-Tag: v6.19-rc1~112^2~54
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=eaa4c8063f7c3b78617c3f5af14d35a782c88144;p=thirdparty%2Flinux.git

mm/khugepaged: remove redundant clearing of struct collapse_control

Patch series "unify PMD scan results and remove redundant cleanup", v2.

This small series addresses two minor cleanup opportunities in the
hugepage collapse logic.

The initial motivation arose during a code review of madvise_collapse(),
where it was noted that the function was missing a handler for
SCAN_PMD_NONE.  This oversight exposed the inconsistent handling of
SCAN_PMD_NULL and SCAN_PMD_NONE.

Since both scan results are functionally identical (they indicate the
absence of a PTE table), the primary patch unifies them into a single,
clearer identifier, SCAN_NO_PTE_TABLE.

The series also takes the opportunity to remove a redundant clearing of
the struct collapse_control.


This patch (of 3):

The structure struct collapse_control is being unnecessarily cleared twice
during the huge page collapse process.

Both hpage_collapse_scan_file() and hpage_collapse_scan_pmd() currently
perform a clear operation on this structure.

Remove the redundant clear operation.

Link: https://lkml.kernel.org/r/20251114030028.7035-1-richard.weiyang@gmail.com
Link: https://lkml.kernel.org/r/20251114030028.7035-2-richard.weiyang@gmail.com
Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Reviewed-by: Dev Jain <dev.jain@arm.com>
Acked-by: David Hildenbrand (Red Hat) <david@kernel.org>
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Reviewed-by: Nico Pache <npache@redhat.com>
Cc: Barry Song <baohua@kernel.org>
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: Ryan Roberts <ryan.roberts@arm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index 7e8cb181d5bd3..1fc8986a28b3d 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -2803,8 +2803,6 @@ int madvise_collapse(struct vm_area_struct *vma, unsigned long start,
 			hend = min(hend, vma->vm_end & HPAGE_PMD_MASK);
 		}
 		mmap_assert_locked(mm);
-		memset(cc->node_load, 0, sizeof(cc->node_load));
-		nodes_clear(cc->alloc_nmask);
 		if (!vma_is_anonymous(vma)) {
 			struct file *file = get_file(vma->vm_file);
 			pgoff_t pgoff = linear_page_index(vma, addr);