From: Liam R. Howlett <Liam.Howlett@oracle.com>
Date: Wed, 29 Oct 2025 16:57:55 +0000 (-0400)
Subject: mm/userfaultfd: Remove hugetlb from userfaultfd by adding
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=bbf1ed20522d71ebc1f7330870107c950bade547;p=users%2Fjedix%2Flinux-maple.git

mm/userfaultfd: Remove hugetlb from userfaultfd by adding
complete_register() to uffd_ops

The registration of uffd has a code block specifically for hugetlb.
Move this block to a uffd_ops and remove the dependency.

The final user of hugetlb code has been removed from userfaultfd.c, so
the hugetlb header can now be removed.

Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
---

diff --git a/include/linux/userfaultfd_k.h b/include/linux/userfaultfd_k.h
index dbf5f7072899..4bf89bde3641 100644
--- a/include/linux/userfaultfd_k.h
+++ b/include/linux/userfaultfd_k.h
@@ -115,6 +115,7 @@ struct uffd_info {
 	.foliop = NULL,							\
 }
 
+void uffd_complete_register(struct vm_area_struct *vma);
 /* VMA userfaultfd operations */
 unsigned int uffd_page_shift(struct vm_area_struct *vma);
 int uffd_writeprotect(struct uffd_info *info);
@@ -136,6 +137,7 @@ struct vm_uffd_ops {
 			struct vm_area_struct *dst, struct folio *folio,
 			unsigned long src_addr);
 	unsigned int (*page_shift)(struct vm_area_struct *src_vma);
+	void (*complete_register)(struct vm_area_struct *vma);
 };
 
 #define MFILL_ATOMIC_MODE_BITS (const_ilog2(NR_MFILL_ATOMIC_MODES - 1) + 1)
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index a725d6ba554e..d457cb268237 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -5534,6 +5534,12 @@ static inline unsigned int hugetlb_page_shift(struct vm_area_struct *vma)
 	return huge_page_shift(hstate_vma(vma));
 }
 
+static inline void hugetlb_complete_register(struct vm_area_struct *vma)
+{
+	if (is_vm_hugetlb_page(vma) && uffd_disable_huge_pmd_share(vma))
+		hugetlb_unshare_all_pmds(vma);
+}
+
 static int hugetlb_mfill_pte_poison(struct uffd_info *info);
 static int hugetlb_mfill_pte_continue(struct uffd_info *info);
 static int hugetlb_mfill_atomic_pte_copy(struct uffd_info *info);
@@ -5549,6 +5555,7 @@ static const struct vm_uffd_ops hugetlb_uffd_ops = {
 	.increment		=	hugetlb_mfill_size,
 	.failed_do_unlock	=	hugetlb_failed_do_unlock,
 	.page_shift		=	hugetlb_page_shift,
+	.complete_register	=	hugetlb_complete_register,
 };
 #endif
 
diff --git a/mm/shmem.c b/mm/shmem.c
index 55d2bb73f8c6..9bebeb1dd76d 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -5278,6 +5278,7 @@ static const struct vm_uffd_ops shmem_uffd_ops = {
 	.increment		=	mfill_size,
 	.failed_do_unlock	=	uffd_failed_do_unlock,
 	.page_shift		=	uffd_page_shift,
+	.complete_register	=	uffd_complete_register,
 };
 #endif
 
diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c
index 7614fe039887..4dc6fac27029 100644
--- a/mm/userfaultfd.c
+++ b/mm/userfaultfd.c
@@ -13,7 +13,6 @@
 #include <linux/swapops.h>
 #include <linux/userfaultfd_k.h>
 #include <linux/mmu_notifier.h>
-#include <linux/hugetlb.h>
 #include <asm/tlbflush.h>
 #include <asm/tlb.h>
 #include "internal.h"
@@ -468,6 +467,9 @@ static ssize_t uffd_def_is_dst_valid(struct vm_area_struct *dst_vma,
 
 	return 0;
 }
+void uffd_complete_register(struct vm_area_struct *vma)
+{
+}
 
 /* Anon vma ops */
 static const struct vm_uffd_ops default_uffd_ops = {
@@ -480,6 +482,7 @@ static const struct vm_uffd_ops default_uffd_ops = {
 	.increment		= mfill_size,
 	.failed_do_unlock	= uffd_failed_do_unlock,
 	.page_shift		= uffd_page_shift,
+	.complete_register	= uffd_complete_register,
 };
 
 unsigned int uffd_page_shift(struct vm_area_struct *vma)
@@ -1887,6 +1890,7 @@ int userfaultfd_register_range(struct userfaultfd_ctx *ctx,
 	struct vm_area_struct *prev = vma_prev(&vmi);
 	unsigned long vma_end;
 	vm_flags_t new_flags;
+	const struct vm_uffd_ops *uffd_ops;
 
 	if (vma->vm_start < start)
 		prev = vma;
@@ -1926,8 +1930,9 @@ int userfaultfd_register_range(struct userfaultfd_ctx *ctx,
 		 */
 		userfaultfd_set_ctx(vma, ctx, vm_flags);
 
-		if (is_vm_hugetlb_page(vma) && uffd_disable_huge_pmd_share(vma))
-			hugetlb_unshare_all_pmds(vma);
+
+		uffd_ops = vma_get_uffd_ops(vma);
+		uffd_ops->complete_register(vma);
 
 skip:
 		prev = vma;