linux-kernel - [PATCH] mm/hugetlb: Remove prepare_hugepage

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Message-ID: <20250627160707.2124580-1-peterx@redhat.com>
Date: Fri, 27 Jun 2025 12:07:07 -0400
From: Peter Xu <peterx@...hat.com>
To: linux-kernel@...r.kernel.org,
	linux-mm@...ck.org
Cc: Andrew Morton <akpm@...ux-foundation.org>,
	peterx@...hat.com,
	"Liam R. Howlett" <Liam.Howlett@...cle.com>,
	Huacai Chen <chenhuacai@...nel.org>,
	Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
	Muchun Song <muchun.song@...ux.dev>,
	Oscar Salvador <osalvador@...e.de>,
	loongarch@...ts.linux.dev,
	linux-mips@...r.kernel.org,
	Jason Gunthorpe <jgg@...dia.com>,
	David Hildenbrand <david@...hat.com>
Subject: [PATCH] mm/hugetlb: Remove prepare_hugepage_range()

Only mips and loongarch implemented this API, however what it does was
checking against stack overflow for either len or addr.  That's already
done in arch's arch_get_unmapped_area*() functions, even though it may not
be 100% identical checks.

For example, for both of the architectures, there will be a trivial
difference on how stack top was defined.  The old code uses STACK_TOP which
may be slightly smaller than TASK_SIZE on either of them, but the hope is
that shouldn't be a problem.

It means the whole API is pretty much obsolete at least now, remove it
completely.

Cc: Liam R. Howlett <Liam.Howlett@...cle.com>
Cc: Huacai Chen <chenhuacai@...nel.org>
Cc: Thomas Bogendoerfer <tsbogend@...ha.franken.de>
Cc: Muchun Song <muchun.song@...ux.dev>
Cc: Oscar Salvador <osalvador@...e.de>
Cc: loongarch@...ts.linux.dev
Cc: linux-mips@...r.kernel.org
Reviewed-by: Jason Gunthorpe <jgg@...dia.com>
Reviewed-by: Oscar Salvador <osalvador@...e.de>
Acked-by: David Hildenbrand <david@...hat.com>
Signed-off-by: Peter Xu <peterx@...hat.com>
---
 arch/loongarch/include/asm/hugetlb.h | 14 --------------
 arch/mips/include/asm/hugetlb.h      | 14 --------------
 fs/hugetlbfs/inode.c                 |  8 ++------
 include/asm-generic/hugetlb.h        |  8 --------
 include/linux/hugetlb.h              |  6 ------
 5 files changed, 2 insertions(+), 48 deletions(-)

diff --git a/arch/loongarch/include/asm/hugetlb.h b/arch/loongarch/include/asm/hugetlb.h
index 4dc4b3e04225..ab68b594f889 100644
--- a/arch/loongarch/include/asm/hugetlb.h
+++ b/arch/loongarch/include/asm/hugetlb.h
@@ -10,20 +10,6 @@
 
 uint64_t pmd_to_entrylo(unsigned long pmd_val);
 
-#define __HAVE_ARCH_PREPARE_HUGEPAGE_RANGE
-static inline int prepare_hugepage_range(struct file *file,
-					 unsigned long addr,
-					 unsigned long len)
-{
-	unsigned long task_size = STACK_TOP;
-
-	if (len > task_size)
-		return -ENOMEM;
-	if (task_size - len < addr)
-		return -EINVAL;
-	return 0;
-}
-
 #define __HAVE_ARCH_HUGE_PTE_CLEAR
 static inline void huge_pte_clear(struct mm_struct *mm, unsigned long addr,
 				  pte_t *ptep, unsigned long sz)
diff --git a/arch/mips/include/asm/hugetlb.h b/arch/mips/include/asm/hugetlb.h
index fbc71ddcf0f6..8c460ce01ffe 100644
--- a/arch/mips/include/asm/hugetlb.h
+++ b/arch/mips/include/asm/hugetlb.h
@@ -11,20 +11,6 @@
 
 #include <asm/page.h>
 
-#define __HAVE_ARCH_PREPARE_HUGEPAGE_RANGE
-static inline int prepare_hugepage_range(struct file *file,
-					 unsigned long addr,
-					 unsigned long len)
-{
-	unsigned long task_size = STACK_TOP;
-
-	if (len > task_size)
-		return -ENOMEM;
-	if (task_size - len < addr)
-		return -EINVAL;
-	return 0;
-}
-
 #define __HAVE_ARCH_HUGE_PTEP_GET_AND_CLEAR
 static inline pte_t huge_ptep_get_and_clear(struct mm_struct *mm,
 					    unsigned long addr, pte_t *ptep,
diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c
index 00b2d1a032fd..81a6acddd690 100644
--- a/fs/hugetlbfs/inode.c
+++ b/fs/hugetlbfs/inode.c
@@ -179,12 +179,8 @@ hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
 
 	if (len & ~huge_page_mask(h))
 		return -EINVAL;
-	if (flags & MAP_FIXED) {
-		if (addr & ~huge_page_mask(h))
-			return -EINVAL;
-		if (prepare_hugepage_range(file, addr, len))
-			return -EINVAL;
-	}
+	if ((flags & MAP_FIXED) && (addr & ~huge_page_mask(h)))
+		return -EINVAL;
 	if (addr)
 		addr0 = ALIGN(addr, huge_page_size(h));
 
diff --git a/include/asm-generic/hugetlb.h b/include/asm-generic/hugetlb.h
index 3e0a8fe9b108..4bce4f07f44f 100644
--- a/include/asm-generic/hugetlb.h
+++ b/include/asm-generic/hugetlb.h
@@ -114,14 +114,6 @@ static inline int huge_pte_none_mostly(pte_t pte)
 }
 #endif
 
-#ifndef __HAVE_ARCH_PREPARE_HUGEPAGE_RANGE
-static inline int prepare_hugepage_range(struct file *file,
-		unsigned long addr, unsigned long len)
-{
-	return 0;
-}
-#endif
-
 #ifndef __HAVE_ARCH_HUGE_PTEP_SET_WRPROTECT
 static inline void huge_ptep_set_wrprotect(struct mm_struct *mm,
 		unsigned long addr, pte_t *ptep)
diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index c6c87eae4a8d..474de8e2a8f2 100644
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -359,12 +359,6 @@ static inline void hugetlb_show_meminfo_node(int nid)
 {
 }
 
-static inline int prepare_hugepage_range(struct file *file,
-				unsigned long addr, unsigned long len)
-{
-	return -EINVAL;
-}
-
 static inline void hugetlb_vma_lock_read(struct vm_area_struct *vma)
 {
 }
-- 
2.49.0