linux-kernel - [PATCH v2 1/4] mm/thp: Allow thp_get_unmapped_area

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Message-ID: <20251204151003.171039-2-peterx@redhat.com>
Date: Thu,  4 Dec 2025 10:10:00 -0500
From: Peter Xu <peterx@...hat.com>
To: kvm@...r.kernel.org,
	linux-mm@...ck.org,
	linux-kernel@...r.kernel.org
Cc: Jason Gunthorpe <jgg@...dia.com>,
	Nico Pache <npache@...hat.com>,
	Zi Yan <ziy@...dia.com>,
	Alex Mastro <amastro@...com>,
	David Hildenbrand <david@...hat.com>,
	Alex Williamson <alex@...zbot.org>,
	Zhi Wang <zhiw@...dia.com>,
	David Laight <david.laight.linux@...il.com>,
	Yi Liu <yi.l.liu@...el.com>,
	Ankit Agrawal <ankita@...dia.com>,
	peterx@...hat.com,
	Kevin Tian <kevin.tian@...el.com>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: [PATCH v2 1/4] mm/thp: Allow thp_get_unmapped_area_vmflags() to take alignment

Add "align" parameter to thp_get_unmapped_area_vmflags() so that it allows
get unmapped area with any alignment.

There're two existing callers, use PMD_SIZE explicitly for them.

No functional change intended.

Signed-off-by: Peter Xu <peterx@...hat.com>
---
 include/linux/huge_mm.h | 5 +++--
 mm/huge_memory.c        | 7 ++++---
 mm/mmap.c               | 3 ++-
 3 files changed, 9 insertions(+), 6 deletions(-)

diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
index 71ac78b9f834f..1c221550362d7 100644
--- a/include/linux/huge_mm.h
+++ b/include/linux/huge_mm.h
@@ -362,7 +362,7 @@ unsigned long thp_get_unmapped_area(struct file *filp, unsigned long addr,
 		unsigned long len, unsigned long pgoff, unsigned long flags);
 unsigned long thp_get_unmapped_area_vmflags(struct file *filp, unsigned long addr,
 		unsigned long len, unsigned long pgoff, unsigned long flags,
-		vm_flags_t vm_flags);
+		unsigned long align, vm_flags_t vm_flags);
 
 bool can_split_folio(struct folio *folio, int caller_pins, int *pextra_pins);
 int split_huge_page_to_list_to_order(struct page *page, struct list_head *list,
@@ -559,7 +559,8 @@ static inline unsigned long thp_vma_allowable_orders(struct vm_area_struct *vma,
 static inline unsigned long
 thp_get_unmapped_area_vmflags(struct file *filp, unsigned long addr,
 			      unsigned long len, unsigned long pgoff,
-			      unsigned long flags, vm_flags_t vm_flags)
+			      unsigned long flags, unsigned long align,
+			      vm_flags_t vm_flags)
 {
 	return 0;
 }
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 6cba1cb14b23a..ab2450b985171 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1155,12 +1155,12 @@ static unsigned long __thp_get_unmapped_area(struct file *filp,
 
 unsigned long thp_get_unmapped_area_vmflags(struct file *filp, unsigned long addr,
 		unsigned long len, unsigned long pgoff, unsigned long flags,
-		vm_flags_t vm_flags)
+		unsigned long align, vm_flags_t vm_flags)
 {
 	unsigned long ret;
 	loff_t off = (loff_t)pgoff << PAGE_SHIFT;
 
-	ret = __thp_get_unmapped_area(filp, addr, len, off, flags, PMD_SIZE, vm_flags);
+	ret = __thp_get_unmapped_area(filp, addr, len, off, flags, align, vm_flags);
 	if (ret)
 		return ret;
 
@@ -1171,7 +1171,8 @@ unsigned long thp_get_unmapped_area_vmflags(struct file *filp, unsigned long add
 unsigned long thp_get_unmapped_area(struct file *filp, unsigned long addr,
 		unsigned long len, unsigned long pgoff, unsigned long flags)
 {
-	return thp_get_unmapped_area_vmflags(filp, addr, len, pgoff, flags, 0);
+	return thp_get_unmapped_area_vmflags(filp, addr, len, pgoff, flags,
+					     PMD_SIZE, 0);
 }
 EXPORT_SYMBOL_GPL(thp_get_unmapped_area);
 
diff --git a/mm/mmap.c b/mm/mmap.c
index 5fd3b80fda1d5..8fa397a18252e 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -846,7 +846,8 @@ __get_unmapped_area(struct file *file, unsigned long addr, unsigned long len,
 		   && IS_ALIGNED(len, PMD_SIZE)) {
 		/* Ensures that larger anonymous mappings are THP aligned. */
 		addr = thp_get_unmapped_area_vmflags(file, addr, len,
-						     pgoff, flags, vm_flags);
+						     pgoff, flags, PMD_SIZE,
+						     vm_flags);
 	} else {
 		addr = mm_get_unmapped_area_vmflags(current->mm, file, addr, len,
 						    pgoff, flags, vm_flags);
-- 
2.50.1