linux-kernel - [PATCH] mm: remove VM_EXEC requirement for THP eligibility

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Message-ID: <20231220054123.1266001-1-maskray@google.com>
Date: Tue, 19 Dec 2023 21:41:23 -0800
From: Fangrui Song <maskray@...gle.com>
To: Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org
Cc: Song Liu <songliubraving@...com>, Yang Shi <shy828301@...il.com>, 
	Miaohe Lin <linmiaohe@...wei.com>, linux-kernel@...r.kernel.org, 
	Fangrui Song <maskray@...gle.com>
Subject: [PATCH] mm: remove VM_EXEC requirement for THP eligibility

Commit e6be37b2e7bd ("mm/huge_memory.c: add missing read-only THP
checking in transparent_hugepage_enabled()") introduced the VM_EXEC
requirement, which is not strictly needed.

lld's default --rosegment option and GNU ld's -z separate-code option
(default on Linux/x86 since binutils 2.31) create a read-only PT_LOAD
segment without the PF_X flag, which should be eligible for THP.

Certain architectures support medium and large code models, where
.lrodata may be placed in a separate read-only PT_LOAD segment, which
should be eligible for THP as well.

Signed-off-by: Fangrui Song <maskray@...gle.com>
---
 include/linux/huge_mm.h | 1 -
 1 file changed, 1 deletion(-)

diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
index fa0350b0812a..4c9e67e9000f 100644
--- a/include/linux/huge_mm.h
+++ b/include/linux/huge_mm.h
@@ -126,7 +126,6 @@ static inline bool file_thp_enabled(struct vm_area_struct *vma)
 	inode = vma->vm_file->f_inode;

 	return (IS_ENABLED(CONFIG_READ_ONLY_THP_FOR_FS)) &&
-	       (vma->vm_flags & VM_EXEC) &&
 	       !inode_is_open_for_write(inode) && S_ISREG(inode->i_mode);
 }

-- 
2.43.0.472.g3155946c3a-goog