linux-kernel - [PATCH next v2 2/2] mm/huge_memory: Use per-VMA hugepage flag hints for exec THP COW

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Message-ID: <20251226100337.4171191-3-zhangqilong3@huawei.com>
Date: Fri, 26 Dec 2025 18:03:37 +0800
From: Zhang Qilong <zhangqilong3@...wei.com>
To: <akpm@...ux-foundation.org>, <david@...nel.org>,
	<lorenzo.stoakes@...cle.com>, <corbet@....net>
CC: <ziy@...dia.com>, <baolin.wang@...ux.alibaba.com>,
	<Liam.Howlett@...cle.com>, <npache@...hat.com>, <ryan.roberts@....com>,
	<dev.jain@....com>, <baohua@...nel.org>, <lance.yang@...ux.dev>,
	<vbabka@...e.cz>, <rppt@...nel.org>, <surenb@...gle.com>, <mhocko@...e.com>,
	<willy@...radead.org>, <wangkefeng.wang@...wei.com>, <sunnanyong@...wei.com>,
	<linux-mm@...ck.org>, <linux-doc@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, <lianux.mm@...il.com>,
	<zhangqilong3@...wei.com>
Subject: [PATCH next v2 2/2] mm/huge_memory: Use per-VMA hugepage flag hints for exec THP COW

Using the per-VMA hugepage flag to avoid system wide default
behavior. If 'vma->vm_flags' indicates a preference for huge pages,
then the exec THP COW can be attempted.

Signed-off-by: Zhang Qilong <zhangqilong3@...wei.com>
---
v2:
- Use 'vma->vm_flags' as hint for exec THP COW suggested by David

---
 mm/memory.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/mm/memory.c b/mm/memory.c
index 691e3ca38cc6..eb2bb36e284c 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -6128,10 +6128,17 @@ static inline vm_fault_t wp_huge_pmd(struct vm_fault *vmf)
 		}
 	}
 
 	if (is_exec_mapping(vm_flags) &&
 	    is_cow_mapping(vm_flags)) {
+		/*
+		 * Reuse the per-VMA flag, only if VM_HUGEPAGE is
+		 * set, do exec THP COW.
+		 */
+		if (!(vm_flags & VM_HUGEPAGE))
+			goto split;
+
 		ret = do_huge_pmd_exec_cow(vmf);
 		if (!(ret & VM_FAULT_FALLBACK))
 			return ret;
 	}
 
-- 
2.43.0