[PATCH 02/10] mm: introduce vma_merge_struct and abstract merge parameters

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Rather than passing around huge numbers of parameters to numerous helper
functions, abstract them into a single struct that we thread through the
operation.

Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@xxxxxxxxxx>
---
 mm/mmap.c |  76 ++++++++------
 mm/vma.c  | 297 ++++++++++++++++++++++++++++++++++++++----------------
 mm/vma.h  |  92 ++++++++---------
 3 files changed, 294 insertions(+), 171 deletions(-)

diff --git a/mm/mmap.c b/mm/mmap.c
index 4a9c2329b09a..f931000c561f 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1369,9 +1369,16 @@ unsigned long mmap_region(struct file *file, unsigned long addr,
 	unsigned long end = addr + len;
 	unsigned long merge_start = addr, merge_end = end;
 	bool writable_file_mapping = false;
-	pgoff_t vm_pgoff;
 	int error;
 	VMA_ITERATOR(vmi, mm, addr);
+	struct vma_merge_struct vmg = {
+		.vmi = &vmi,
+		.start = addr,
+		.end = end,
+		.flags = vm_flags,
+		.pgoff = pgoff,
+		.file = file,
+	};
 
 	/* Check against address space limit. */
 	if (!may_expand_vm(mm, vm_flags, len >> PAGE_SHIFT)) {
@@ -1405,8 +1412,8 @@ unsigned long mmap_region(struct file *file, unsigned long addr,
 		vm_flags |= VM_ACCOUNT;
 	}
 
-	next = vma_next(&vmi);
-	prev = vma_prev(&vmi);
+	next = vmg.next = vma_next(&vmi);
+	prev = vmg.prev = vma_prev(&vmi);
 	if (vm_flags & VM_SPECIAL) {
 		if (prev)
 			vma_iter_next_range(&vmi);
@@ -1416,29 +1423,30 @@ unsigned long mmap_region(struct file *file, unsigned long addr,
 	/* Attempt to expand an old mapping */
 	/* Check next */
 	if (next && next->vm_start == end && !vma_policy(next) &&
-	    can_vma_merge_before(next, vm_flags, NULL, file, pgoff+pglen,
-				 NULL_VM_UFFD_CTX, NULL)) {
+	    can_vma_merge_before(&vmg)) {
 		merge_end = next->vm_end;
 		vma = next;
-		vm_pgoff = next->vm_pgoff - pglen;
+		vmg.pgoff = next->vm_pgoff - pglen;
+	}
+
+	if (vma) {
+		vmg.anon_vma = vma->anon_vma;
+		vmg.uffd_ctx = vma->vm_userfaultfd_ctx;
 	}
 
 	/* Check prev */
 	if (prev && prev->vm_end == addr && !vma_policy(prev) &&
-	    (vma ? can_vma_merge_after(prev, vm_flags, vma->anon_vma, file,
-				       pgoff, vma->vm_userfaultfd_ctx, NULL) :
-		   can_vma_merge_after(prev, vm_flags, NULL, file, pgoff,
-				       NULL_VM_UFFD_CTX, NULL))) {
+	    can_vma_merge_after(&vmg)) {
 		merge_start = prev->vm_start;
 		vma = prev;
-		vm_pgoff = prev->vm_pgoff;
+		vmg.pgoff = prev->vm_pgoff;
 	} else if (prev) {
 		vma_iter_next_range(&vmi);
 	}
 
 	/* Actually expand, if possible */
 	if (vma &&
-	    !vma_expand(&vmi, vma, merge_start, merge_end, vm_pgoff, next)) {
+	    !vma_expand(&vmi, vma, merge_start, merge_end, vmg.pgoff, next)) {
 		khugepaged_enter_vma(vma, vm_flags);
 		goto expanded;
 	}
@@ -1790,25 +1798,31 @@ static int do_brk_flags(struct vma_iterator *vmi, struct vm_area_struct *vma,
 	 * Expand the existing vma if possible; Note that singular lists do not
 	 * occur after forking, so the expand will only happen on new VMAs.
 	 */
-	if (vma && vma->vm_end == addr && !vma_policy(vma) &&
-	    can_vma_merge_after(vma, flags, NULL, NULL,
-				addr >> PAGE_SHIFT, NULL_VM_UFFD_CTX, NULL)) {
-		vma_iter_config(vmi, vma->vm_start, addr + len);
-		if (vma_iter_prealloc(vmi, vma))
-			goto unacct_fail;
-
-		vma_start_write(vma);
-
-		init_vma_prep(&vp, vma);
-		vma_prepare(&vp);
-		vma_adjust_trans_huge(vma, vma->vm_start, addr + len, 0);
-		vma->vm_end = addr + len;
-		vm_flags_set(vma, VM_SOFTDIRTY);
-		vma_iter_store(vmi, vma);
-
-		vma_complete(&vp, vmi, mm);
-		khugepaged_enter_vma(vma, flags);
-		goto out;
+	if (vma && vma->vm_end == addr && !vma_policy(vma)) {
+		struct vma_merge_struct vmg = {
+			.prev = vma,
+			.flags = flags,
+			.pgoff = addr >> PAGE_SHIFT,
+		};
+
+		if (can_vma_merge_after(&vmg)) {
+			vma_iter_config(vmi, vma->vm_start, addr + len);
+			if (vma_iter_prealloc(vmi, vma))
+				goto unacct_fail;
+
+			vma_start_write(vma);
+
+			init_vma_prep(&vp, vma);
+			vma_prepare(&vp);
+			vma_adjust_trans_huge(vma, vma->vm_start, addr + len, 0);
+			vma->vm_end = addr + len;
+			vm_flags_set(vma, VM_SOFTDIRTY);
+			vma_iter_store(vmi, vma);
+
+			vma_complete(&vp, vmi, mm);
+			khugepaged_enter_vma(vma, flags);
+			goto out;
+		}
 	}
 
 	if (vma)
diff --git a/mm/vma.c b/mm/vma.c
index bf0546fe6eab..20c4ce7712c0 100644
--- a/mm/vma.c
+++ b/mm/vma.c
@@ -7,16 +7,18 @@
 #include "vma_internal.h"
 #include "vma.h"
 
-/*
- * If the vma has a ->close operation then the driver probably needs to release
- * per-vma resources, so we don't attempt to merge those if the caller indicates
- * the current vma may be removed as part of the merge.
- */
-static inline bool is_mergeable_vma(struct vm_area_struct *vma,
-		struct file *file, unsigned long vm_flags,
-		struct vm_userfaultfd_ctx vm_userfaultfd_ctx,
-		struct anon_vma_name *anon_name, bool may_remove_vma)
+static inline bool is_mergeable_vma(struct vma_merge_struct *vmg, bool merge_next)
 {
+	struct vm_area_struct *vma = merge_next ? vmg->next : vmg->prev;
+	/*
+	 * If the vma has a ->close operation then the driver probably needs to
+	 * release per-vma resources, so we don't attempt to merge those if the
+	 * caller indicates the current vma may be removed as part of the merge,
+	 * which is the case if we are attempting to merge the next VMA into
+	 * this one.
+	 */
+	bool may_remove_vma = merge_next;
+
 	/*
 	 * VM_SOFTDIRTY should not prevent from VMA merging, if we
 	 * match the flags but dirty bit -- the caller should mark
@@ -25,15 +27,15 @@ static inline bool is_mergeable_vma(struct vm_area_struct *vma,
 	 * the kernel to generate new VMAs when old one could be
 	 * extended instead.
 	 */
-	if ((vma->vm_flags ^ vm_flags) & ~VM_SOFTDIRTY)
+	if ((vma->vm_flags ^ vmg->flags) & ~VM_SOFTDIRTY)
 		return false;
-	if (vma->vm_file != file)
+	if (vma->vm_file != vmg->file)
 		return false;
 	if (may_remove_vma && vma->vm_ops && vma->vm_ops->close)
 		return false;
-	if (!is_mergeable_vm_userfaultfd_ctx(vma, vm_userfaultfd_ctx))
+	if (!is_mergeable_vm_userfaultfd_ctx(vma, vmg->uffd_ctx))
 		return false;
-	if (!anon_vma_name_eq(anon_vma_name(vma), anon_name))
+	if (!anon_vma_name_eq(anon_vma_name(vma), vmg->anon_name))
 		return false;
 	return true;
 }
@@ -94,16 +96,16 @@ static void init_multi_vma_prep(struct vma_prepare *vp,
  * We assume the vma may be removed as part of the merge.
  */
 bool
-can_vma_merge_before(struct vm_area_struct *vma, unsigned long vm_flags,
-		struct anon_vma *anon_vma, struct file *file,
-		pgoff_t vm_pgoff, struct vm_userfaultfd_ctx vm_userfaultfd_ctx,
-		struct anon_vma_name *anon_name)
+can_vma_merge_before(struct vma_merge_struct *vmg)
 {
-	if (is_mergeable_vma(vma, file, vm_flags, vm_userfaultfd_ctx, anon_name, true) &&
-	    is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) {
-		if (vma->vm_pgoff == vm_pgoff)
+	pgoff_t pglen = PHYS_PFN(vmg->end - vmg->start);
+
+	if (is_mergeable_vma(vmg, true) &&
+	    is_mergeable_anon_vma(vmg->anon_vma, vmg->next->anon_vma, vmg->next)) {
+		if (vmg->next->vm_pgoff == vmg->pgoff + pglen)
 			return true;
 	}
+
 	return false;
 }
 
@@ -116,18 +118,11 @@ can_vma_merge_before(struct vm_area_struct *vma, unsigned long vm_flags,
  *
  * We assume that vma is not removed as part of the merge.
  */
-bool
-can_vma_merge_after(struct vm_area_struct *vma, unsigned long vm_flags,
-		struct anon_vma *anon_vma, struct file *file,
-		pgoff_t vm_pgoff, struct vm_userfaultfd_ctx vm_userfaultfd_ctx,
-		struct anon_vma_name *anon_name)
+bool can_vma_merge_after(struct vma_merge_struct *vmg)
 {
-	if (is_mergeable_vma(vma, file, vm_flags, vm_userfaultfd_ctx, anon_name, false) &&
-	    is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) {
-		pgoff_t vm_pglen;
-
-		vm_pglen = vma_pages(vma);
-		if (vma->vm_pgoff + vm_pglen == vm_pgoff)
+	if (is_mergeable_vma(vmg, false) &&
+	    is_mergeable_anon_vma(vmg->anon_vma, vmg->prev->anon_vma, vmg->prev)) {
+		if (vmg->prev->vm_pgoff + vma_pages(vmg->prev) == vmg->pgoff)
 			return true;
 	}
 	return false;
@@ -180,7 +175,7 @@ void unmap_region(struct mm_struct *mm, struct ma_state *mas,
  * VMA Iterator will point to the end VMA.
  */
 static int __split_vma(struct vma_iterator *vmi, struct vm_area_struct *vma,
-		       unsigned long addr, int new_below)
+		       unsigned long addr, bool new_below)
 {
 	struct vma_prepare vp;
 	struct vm_area_struct *new;
@@ -261,13 +256,14 @@ static int __split_vma(struct vma_iterator *vmi, struct vm_area_struct *vma,
  * Split a vma into two pieces at address 'addr', a new vma is allocated
  * either for the first part or the tail.
  */
-static int split_vma(struct vma_iterator *vmi, struct vm_area_struct *vma,
-		     unsigned long addr, int new_below)
+static int split_vma(struct vma_merge_struct *vmg, bool new_below)
 {
-	if (vma->vm_mm->map_count >= sysctl_max_map_count)
+	if (vmg->vma->vm_mm->map_count >= sysctl_max_map_count)
 		return -ENOMEM;
 
-	return __split_vma(vmi, vma, addr, new_below);
+	return __split_vma(vmg->vmi, vmg->vma,
+			   new_below ? vmg->start : vmg->end,
+			   new_below);
 }
 
 /*
@@ -712,7 +708,7 @@ do_vmi_align_munmap(struct vma_iterator *vmi, struct vm_area_struct *vma,
 		if (end < vma->vm_end && mm->map_count >= sysctl_max_map_count)
 			goto map_count_exceeded;
 
-		error = __split_vma(vmi, vma, start, 1);
+		error = __split_vma(vmi, vma, start, true);
 		if (error)
 			goto start_split_failed;
 	}
@@ -725,7 +721,7 @@ do_vmi_align_munmap(struct vma_iterator *vmi, struct vm_area_struct *vma,
 	do {
 		/* Does it split the end? */
 		if (next->vm_end > end) {
-			error = __split_vma(vmi, next, end, 0);
+			error = __split_vma(vmi, next, end, false);
 			if (error)
 				goto end_split_failed;
 		}
@@ -934,16 +930,10 @@ int do_vmi_munmap(struct vma_iterator *vmi, struct mm_struct *mm,
  * **** is not represented - it will be merged and the vma containing the
  *      area is returned, or the function will return NULL
  */
-static struct vm_area_struct
-*vma_merge(struct vma_iterator *vmi, struct vm_area_struct *prev,
-	   struct vm_area_struct *src, unsigned long addr, unsigned long end,
-	   unsigned long vm_flags, pgoff_t pgoff, struct mempolicy *policy,
-	   struct vm_userfaultfd_ctx vm_userfaultfd_ctx,
-	   struct anon_vma_name *anon_name)
+static struct vm_area_struct *vma_merge(struct vma_merge_struct *vmg)
 {
-	struct mm_struct *mm = src->vm_mm;
-	struct anon_vma *anon_vma = src->anon_vma;
-	struct file *file = src->vm_file;
+	struct mm_struct *mm = container_of(vmg->vmi->mas.tree, struct mm_struct, mm_mt);
+	struct vm_area_struct *prev = vmg->prev;
 	struct vm_area_struct *curr, *next, *res;
 	struct vm_area_struct *vma, *adjust, *remove, *remove2;
 	struct vm_area_struct *anon_dup = NULL;
@@ -953,16 +943,18 @@ static struct vm_area_struct
 	bool merge_prev = false;
 	bool merge_next = false;
 	bool vma_expanded = false;
+	unsigned long addr = vmg->start;
+	unsigned long end = vmg->end;
 	unsigned long vma_start = addr;
 	unsigned long vma_end = end;
-	pgoff_t pglen = (end - addr) >> PAGE_SHIFT;
+	pgoff_t pglen = PHYS_PFN(end - addr);
 	long adj_start = 0;
 
 	/*
 	 * We later require that vma->vm_flags == vm_flags,
 	 * so this tests vma->vm_flags & VM_SPECIAL, too.
 	 */
-	if (vm_flags & VM_SPECIAL)
+	if (vmg->flags & VM_SPECIAL)
 		return NULL;
 
 	/* Does the input range span an existing VMA? (cases 5 - 8) */
@@ -970,27 +962,26 @@ static struct vm_area_struct
 
 	if (!curr ||			/* cases 1 - 4 */
 	    end == curr->vm_end)	/* cases 6 - 8, adjacent VMA */
-		next = vma_lookup(mm, end);
+		next = vmg->next = vma_lookup(mm, end);
 	else
-		next = NULL;		/* case 5 */
+		next = vmg->next = NULL;	/* case 5 */
 
 	if (prev) {
 		vma_start = prev->vm_start;
 		vma_pgoff = prev->vm_pgoff;
 
 		/* Can we merge the predecessor? */
-		if (addr == prev->vm_end && mpol_equal(vma_policy(prev), policy)
-		    && can_vma_merge_after(prev, vm_flags, anon_vma, file,
-					   pgoff, vm_userfaultfd_ctx, anon_name)) {
+		if (addr == prev->vm_end && mpol_equal(vma_policy(prev), vmg->policy)
+		    && can_vma_merge_after(vmg)) {
+
 			merge_prev = true;
-			vma_prev(vmi);
+			vma_prev(vmg->vmi);
 		}
 	}
 
 	/* Can we merge the successor? */
-	if (next && mpol_equal(policy, vma_policy(next)) &&
-	    can_vma_merge_before(next, vm_flags, anon_vma, file, pgoff+pglen,
-				 vm_userfaultfd_ctx, anon_name)) {
+	if (next && mpol_equal(vmg->policy, vma_policy(next)) &&
+	    can_vma_merge_before(vmg)) {
 		merge_next = true;
 	}
 
@@ -1041,7 +1032,7 @@ static struct vm_area_struct
 				remove = curr;
 			} else {			/* case 5 */
 				adjust = curr;
-				adj_start = (end - curr->vm_start);
+				adj_start = end - curr->vm_start;
 			}
 			if (!err)
 				err = dup_anon_vma(prev, curr, &anon_dup);
@@ -1081,13 +1072,13 @@ static struct vm_area_struct
 		vma_expanded = true;
 
 	if (vma_expanded) {
-		vma_iter_config(vmi, vma_start, vma_end);
+		vma_iter_config(vmg->vmi, vma_start, vma_end);
 	} else {
-		vma_iter_config(vmi, adjust->vm_start + adj_start,
+		vma_iter_config(vmg->vmi, adjust->vm_start + adj_start,
 				adjust->vm_end);
 	}
 
-	if (vma_iter_prealloc(vmi, vma))
+	if (vma_iter_prealloc(vmg->vmi, vma))
 		goto prealloc_fail;
 
 	init_multi_vma_prep(&vp, vma, adjust, remove, remove2);
@@ -1099,19 +1090,19 @@ static struct vm_area_struct
 	vma_set_range(vma, vma_start, vma_end, vma_pgoff);
 
 	if (vma_expanded)
-		vma_iter_store(vmi, vma);
+		vma_iter_store(vmg->vmi, vma);
 
 	if (adj_start) {
 		adjust->vm_start += adj_start;
 		adjust->vm_pgoff += adj_start >> PAGE_SHIFT;
 		if (adj_start < 0) {
 			WARN_ON(vma_expanded);
-			vma_iter_store(vmi, next);
+			vma_iter_store(vmg->vmi, next);
 		}
 	}
 
-	vma_complete(&vp, vmi, mm);
-	khugepaged_enter_vma(res, vm_flags);
+	vma_complete(&vp, vmg->vmi, mm);
+	khugepaged_enter_vma(res, vmg->flags);
 	return res;
 
 prealloc_fail:
@@ -1119,8 +1110,8 @@ static struct vm_area_struct
 		unlink_anon_vmas(anon_dup);
 
 anon_vma_fail:
-	vma_iter_set(vmi, addr);
-	vma_iter_load(vmi);
+	vma_iter_set(vmg->vmi, addr);
+	vma_iter_load(vmg->vmi);
 	return NULL;
 }
 
@@ -1137,38 +1128,141 @@ static struct vm_area_struct
  * The function returns either the merged VMA, the original VMA if a split was
  * required instead, or an error if the split failed.
  */
-struct vm_area_struct *vma_modify(struct vma_iterator *vmi,
-				  struct vm_area_struct *prev,
-				  struct vm_area_struct *vma,
-				  unsigned long start, unsigned long end,
-				  unsigned long vm_flags,
-				  struct mempolicy *policy,
-				  struct vm_userfaultfd_ctx uffd_ctx,
-				  struct anon_vma_name *anon_name)
+static struct vm_area_struct *vma_modify(struct vma_merge_struct *vmg)
 {
-	pgoff_t pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
+	struct vm_area_struct *vma = vmg->vma;
 	struct vm_area_struct *merged;
 
-	merged = vma_merge(vmi, prev, vma, start, end, vm_flags,
-			   pgoff, policy, uffd_ctx, anon_name);
+	/* First, try to merge. */
+	merged = vma_merge(vmg);
 	if (merged)
 		return merged;
 
-	if (vma->vm_start < start) {
-		int err = split_vma(vmi, vma, start, 1);
+	/* Split any preceding portion of the VMA. */
+	if (vma->vm_start < vmg->start) {
+		int err = split_vma(vmg, true);
 
 		if (err)
 			return ERR_PTR(err);
 	}
 
-	if (vma->vm_end > end) {
-		int err = split_vma(vmi, vma, end, 0);
+	/* Split any trailing portion of the VMA. */
+	if (vma->vm_end > vmg->end) {
+		int err = split_vma(vmg, false);
 
 		if (err)
 			return ERR_PTR(err);
 	}
 
-	return vma;
+	return vmg->vma;
+}
+
+/* Assumes addr >= vma->vm_start. */
+static pgoff_t vma_pgoff_offset(struct vm_area_struct *vma, unsigned long addr)
+{
+	return vma->vm_pgoff + PHYS_PFN(addr - vma->vm_start);
+}
+
+struct vm_area_struct *vma_modify_flags(struct vma_iterator *vmi,
+					struct vm_area_struct *prev,
+					struct vm_area_struct *vma,
+					unsigned long start, unsigned long end,
+					unsigned long new_flags)
+{
+	struct vma_merge_struct vmg = {
+		.vmi = vmi,
+		.prev = prev,
+		.vma = vma,
+		.start = start,
+		.end = end,
+		.flags = new_flags,
+		.pgoff = vma_pgoff_offset(vma, start),
+		.file = vma->vm_file,
+		.anon_vma = vma->anon_vma,
+		.policy = vma_policy(vma),
+		.uffd_ctx = vma->vm_userfaultfd_ctx,
+		.anon_name = anon_vma_name(vma),
+	};
+
+	return vma_modify(&vmg);
+}
+
+struct vm_area_struct
+*vma_modify_flags_name(struct vma_iterator *vmi,
+		       struct vm_area_struct *prev,
+		       struct vm_area_struct *vma,
+		       unsigned long start,
+		       unsigned long end,
+		       unsigned long new_flags,
+		       struct anon_vma_name *new_name)
+{
+	struct vma_merge_struct vmg = {
+		.vmi = vmi,
+		.prev = prev,
+		.vma = vma,
+		.start = start,
+		.end = end,
+		.flags = new_flags,
+		.pgoff = vma_pgoff_offset(vma, start),
+		.file = vma->vm_file,
+		.anon_vma = vma->anon_vma,
+		.policy = vma_policy(vma),
+		.uffd_ctx = vma->vm_userfaultfd_ctx,
+		.anon_name = new_name,
+	};
+
+	return vma_modify(&vmg);
+}
+
+struct vm_area_struct
+*vma_modify_policy(struct vma_iterator *vmi,
+		   struct vm_area_struct *prev,
+		   struct vm_area_struct *vma,
+		   unsigned long start, unsigned long end,
+		   struct mempolicy *new_pol)
+{
+	struct vma_merge_struct vmg = {
+		.vmi = vmi,
+		.prev = prev,
+		.vma = vma,
+		.start = start,
+		.end = end,
+		.flags = vma->vm_flags,
+		.pgoff = vma_pgoff_offset(vma, start),
+		.file = vma->vm_file,
+		.anon_vma = vma->anon_vma,
+		.policy = new_pol,
+		.uffd_ctx = vma->vm_userfaultfd_ctx,
+		.anon_name = anon_vma_name(vma),
+	};
+
+	return vma_modify(&vmg);
+}
+
+struct vm_area_struct
+*vma_modify_flags_uffd(struct vma_iterator *vmi,
+		       struct vm_area_struct *prev,
+		       struct vm_area_struct *vma,
+		       unsigned long start, unsigned long end,
+		       unsigned long new_flags,
+		       struct vm_userfaultfd_ctx new_ctx)
+{
+	struct vma_merge_struct vmg = {
+		.vmi = vmi,
+		.prev = prev,
+		.vma = vma,
+		.start = start,
+		.end = end,
+		.flags = new_flags,
+		.file = vma->vm_file,
+		.anon_vma = vma->anon_vma,
+		.pgoff = vma_pgoff_offset(vma, start),
+		.policy = vma_policy(vma),
+		.uffd_ctx = new_ctx,
+		.anon_name = anon_vma_name(vma),
+	};
+
+	return vma_modify(&vmg);
 }
 
 /*
@@ -1180,8 +1274,22 @@ struct vm_area_struct
 		   struct vm_area_struct *vma, unsigned long start,
 		   unsigned long end, pgoff_t pgoff)
 {
-	return vma_merge(vmi, prev, vma, start, end, vma->vm_flags, pgoff,
-			 vma_policy(vma), vma->vm_userfaultfd_ctx, anon_vma_name(vma));
+	struct vma_merge_struct vmg = {
+		.vmi = vmi,
+		.prev = prev,
+		.vma = vma,
+		.start = start,
+		.end = end,
+		.flags = vma->vm_flags,
+		.file = vma->vm_file,
+		.anon_vma = vma->anon_vma,
+		.pgoff = pgoff,
+		.policy = vma_policy(vma),
+		.uffd_ctx = vma->vm_userfaultfd_ctx,
+		.anon_name = anon_vma_name(vma),
+	};
+
+	return vma_merge(&vmg);
 }
 
 /*
@@ -1193,11 +1301,22 @@ struct vm_area_struct *vma_merge_extend(struct vma_iterator *vmi,
 					unsigned long delta)
 {
 	pgoff_t pgoff = vma->vm_pgoff + vma_pages(vma);
+	struct vma_merge_struct vmg = {
+		.vmi = vmi,
+		.prev = vma,
+		.vma = vma,
+		.start = vma->vm_end,
+		.end = vma->vm_end + delta,
+		.flags = vma->vm_flags,
+		.file = vma->vm_file,
+		.pgoff = pgoff,
+		.policy = vma_policy(vma),
+		.uffd_ctx = vma->vm_userfaultfd_ctx,
+		.anon_name = anon_vma_name(vma),
+	};
 
 	/* vma is specified as prev, so case 1 or 2 will apply. */
-	return vma_merge(vmi, vma, vma, vma->vm_end, vma->vm_end + delta,
-			 vma->vm_flags, pgoff, vma_policy(vma),
-			 vma->vm_userfaultfd_ctx, anon_vma_name(vma));
+	return vma_merge(&vmg);
 }
 
 void unlink_file_vma_batch_init(struct unlink_vma_file_batch *vb)
diff --git a/mm/vma.h b/mm/vma.h
index 6efdf1768a0a..c31684cc1da6 100644
--- a/mm/vma.h
+++ b/mm/vma.h
@@ -26,6 +26,23 @@ struct unlink_vma_file_batch {
 	struct vm_area_struct *vmas[8];
 };
 
+/* Represents a VMA merge operation. */
+struct vma_merge_struct {
+	struct vma_iterator *vmi;
+	struct vm_area_struct *prev;
+	struct vm_area_struct *next; /* Modified by vma_merge(). */
+	struct vm_area_struct *vma; /* Either a new VMA or the one being modified. */
+	unsigned long start;
+	unsigned long end;
+	unsigned long flags;
+	pgoff_t pgoff;
+	struct file *file;
+	struct anon_vma *anon_vma;
+	struct mempolicy *policy;
+	struct vm_userfaultfd_ctx uffd_ctx;
+	struct anon_vma_name *anon_name;
+};
+
 #ifdef CONFIG_DEBUG_VM_MAPLE_TREE
 void validate_mm(struct mm_struct *mm);
 #else
@@ -72,80 +89,53 @@ void unmap_region(struct mm_struct *mm, struct ma_state *mas,
 		struct vm_area_struct *next, unsigned long start,
 		unsigned long end, unsigned long tree_end, bool mm_wr_locked);
 
-/* Required by mmap_region(). */
-bool
-can_vma_merge_before(struct vm_area_struct *vma, unsigned long vm_flags,
-		struct anon_vma *anon_vma, struct file *file,
-		pgoff_t vm_pgoff, struct vm_userfaultfd_ctx vm_userfaultfd_ctx,
-		struct anon_vma_name *anon_name);
-
-/* Required by mmap_region() and do_brk_flags(). */
-bool
-can_vma_merge_after(struct vm_area_struct *vma, unsigned long vm_flags,
-		struct anon_vma *anon_vma, struct file *file,
-		pgoff_t vm_pgoff, struct vm_userfaultfd_ctx vm_userfaultfd_ctx,
-		struct anon_vma_name *anon_name);
-
-struct vm_area_struct *vma_modify(struct vma_iterator *vmi,
-				  struct vm_area_struct *prev,
-				  struct vm_area_struct *vma,
-				  unsigned long start, unsigned long end,
-				  unsigned long vm_flags,
-				  struct mempolicy *policy,
-				  struct vm_userfaultfd_ctx uffd_ctx,
-				  struct anon_vma_name *anon_name);
+/*
+ * Can we merge the VMA described by vmg into the following VMA vmg->next?
+ *
+ * Required by mmap_region().
+ */
+bool can_vma_merge_before(struct vma_merge_struct *vmg);
+
+/*
+ * Can we merge the VMA described by vmg into the preceding VMA vmg->prev?
+ *
+ * Required by mmap_region() and do_brk_flags().
+ */
+bool can_vma_merge_after(struct vma_merge_struct *vmg);
 
 /* We are about to modify the VMA's flags. */
-static inline struct vm_area_struct
-*vma_modify_flags(struct vma_iterator *vmi,
-		  struct vm_area_struct *prev,
-		  struct vm_area_struct *vma,
-		  unsigned long start, unsigned long end,
-		  unsigned long new_flags)
-{
-	return vma_modify(vmi, prev, vma, start, end, new_flags,
-			  vma_policy(vma), vma->vm_userfaultfd_ctx,
-			  anon_vma_name(vma));
-}
+struct vm_area_struct *vma_modify_flags(struct vma_iterator *vmi,
+					struct vm_area_struct *prev,
+					struct vm_area_struct *vma,
+					unsigned long start, unsigned long end,
+					unsigned long new_flags);
 
 /* We are about to modify the VMA's flags and/or anon_name. */
-static inline struct vm_area_struct
+struct vm_area_struct
 *vma_modify_flags_name(struct vma_iterator *vmi,
 		       struct vm_area_struct *prev,
 		       struct vm_area_struct *vma,
 		       unsigned long start,
 		       unsigned long end,
 		       unsigned long new_flags,
-		       struct anon_vma_name *new_name)
-{
-	return vma_modify(vmi, prev, vma, start, end, new_flags,
-			  vma_policy(vma), vma->vm_userfaultfd_ctx, new_name);
-}
+		       struct anon_vma_name *new_name);
 
 /* We are about to modify the VMA's memory policy. */
-static inline struct vm_area_struct
+struct vm_area_struct
 *vma_modify_policy(struct vma_iterator *vmi,
 		   struct vm_area_struct *prev,
 		   struct vm_area_struct *vma,
 		   unsigned long start, unsigned long end,
-		   struct mempolicy *new_pol)
-{
-	return vma_modify(vmi, prev, vma, start, end, vma->vm_flags,
-			  new_pol, vma->vm_userfaultfd_ctx, anon_vma_name(vma));
-}
+		   struct mempolicy *new_pol);
 
 /* We are about to modify the VMA's flags and/or uffd context. */
-static inline struct vm_area_struct
+struct vm_area_struct
 *vma_modify_flags_uffd(struct vma_iterator *vmi,
 		       struct vm_area_struct *prev,
 		       struct vm_area_struct *vma,
 		       unsigned long start, unsigned long end,
 		       unsigned long new_flags,
-		       struct vm_userfaultfd_ctx new_ctx)
-{
-	return vma_modify(vmi, prev, vma, start, end, new_flags,
-			  vma_policy(vma), new_ctx, anon_vma_name(vma));
-}
+		       struct vm_userfaultfd_ctx new_ctx);
 
 struct vm_area_struct
 *vma_merge_new_vma(struct vma_iterator *vmi, struct vm_area_struct *prev,
-- 
2.45.2





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