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From:   Liam Howlett <liam.howlett@oracle.com>
To:     "maple-tree@lists.infradead.org" <maple-tree@lists.infradead.org>,
        "linux-mm@kvack.org" <linux-mm@kvack.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>
CC:     Liam Howlett <liam.howlett@oracle.com>,
        Liam Howlett <liam.howlett@oracle.com>
Subject: [PATCH v2 06/44] mm/mmap: convert brk to use vma iterator
Thread-Topic: [PATCH v2 06/44] mm/mmap: convert brk to use vma iterator
Thread-Index: AQHZIToh2YIFO4Pea0W8K6URlm/QaQ==
Date:   Thu, 5 Jan 2023 19:15:54 +0000
Message-ID: <20230105191517.3099082-7-Liam.Howlett@oracle.com>
References: <20230105191517.3099082-1-Liam.Howlett@oracle.com>
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From: "Liam R. Howlett" <Liam.Howlett@Oracle.com>

Use the vma iterator API for the brk() system call.  This will provide
type safety at compile time.

Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
---
 mm/mmap.c | 47 +++++++++++++++++++++++------------------------
 1 file changed, 23 insertions(+), 24 deletions(-)

diff --git a/mm/mmap.c b/mm/mmap.c
index 9318f2ac8a6e..4a6f42ab3560 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -239,10 +239,10 @@ static int check_brk_limits(unsigned long addr, unsig=
ned long len)
=20
 	return mlock_future_check(current->mm, current->mm->def_flags, len);
 }
-static int do_brk_munmap(struct ma_state *mas, struct vm_area_struct *vma,
+static int do_brk_munmap(struct vma_iterator *vmi, struct vm_area_struct *=
vma,
 			 unsigned long newbrk, unsigned long oldbrk,
 			 struct list_head *uf);
-static int do_brk_flags(struct ma_state *mas, struct vm_area_struct *brkvm=
a,
+static int do_brk_flags(struct vma_iterator *vmi, struct vm_area_struct *b=
rkvma,
 		unsigned long addr, unsigned long request, unsigned long flags);
 SYSCALL_DEFINE1(brk, unsigned long, brk)
 {
@@ -253,7 +253,7 @@ SYSCALL_DEFINE1(brk, unsigned long, brk)
 	bool populate;
 	bool downgraded =3D false;
 	LIST_HEAD(uf);
-	MA_STATE(mas, &mm->mm_mt, 0, 0);
+	struct vma_iterator vmi;
=20
 	if (mmap_write_lock_killable(mm))
 		return -EINTR;
@@ -301,8 +301,8 @@ SYSCALL_DEFINE1(brk, unsigned long, brk)
 		int ret;
=20
 		/* Search one past newbrk */
-		mas_set(&mas, newbrk);
-		brkvma =3D mas_find(&mas, oldbrk);
+		vma_iter_init(&vmi, mm, newbrk);
+		brkvma =3D vma_find(&vmi, oldbrk);
 		if (!brkvma || brkvma->vm_start >=3D oldbrk)
 			goto out; /* mapping intersects with an existing non-brk vma. */
 		/*
@@ -311,7 +311,7 @@ SYSCALL_DEFINE1(brk, unsigned long, brk)
 		 * before calling do_brk_munmap().
 		 */
 		mm->brk =3D brk;
-		ret =3D do_brk_munmap(&mas, brkvma, newbrk, oldbrk, &uf);
+		ret =3D do_brk_munmap(&vmi, brkvma, newbrk, oldbrk, &uf);
 		if (ret =3D=3D 1)  {
 			downgraded =3D true;
 			goto success;
@@ -329,14 +329,14 @@ SYSCALL_DEFINE1(brk, unsigned long, brk)
 	 * Only check if the next VMA is within the stack_guard_gap of the
 	 * expansion area
 	 */
-	mas_set(&mas, oldbrk);
-	next =3D mas_find(&mas, newbrk - 1 + PAGE_SIZE + stack_guard_gap);
+	vma_iter_init(&vmi, mm, oldbrk);
+	next =3D vma_find(&vmi, newbrk + PAGE_SIZE + stack_guard_gap);
 	if (next && newbrk + PAGE_SIZE > vm_start_gap(next))
 		goto out;
=20
-	brkvma =3D mas_prev(&mas, mm->start_brk);
+	brkvma =3D vma_prev_limit(&vmi, mm->start_brk);
 	/* Ok, looks good - let it rip. */
-	if (do_brk_flags(&mas, brkvma, oldbrk, newbrk - oldbrk, 0) < 0)
+	if (do_brk_flags(&vmi, brkvma, oldbrk, newbrk - oldbrk, 0) < 0)
 		goto out;
=20
 	mm->brk =3D brk;
@@ -2963,7 +2963,7 @@ SYSCALL_DEFINE5(remap_file_pages, unsigned long, star=
t, unsigned long, size,
=20
 /*
  * brk_munmap() - Unmap a parital vma.
- * @mas: The maple tree state.
+ * @vmi: The vma iterator
  * @vma: The vma to be modified
  * @newbrk: the start of the address to unmap
  * @oldbrk: The end of the address to unmap
@@ -2973,7 +2973,7 @@ SYSCALL_DEFINE5(remap_file_pages, unsigned long, star=
t, unsigned long, size,
  * unmaps a partial VMA mapping.  Does not handle alignment, downgrades lo=
ck if
  * possible.
  */
-static int do_brk_munmap(struct ma_state *mas, struct vm_area_struct *vma,
+static int do_brk_munmap(struct vma_iterator *vmi, struct vm_area_struct *=
vma,
 			 unsigned long newbrk, unsigned long oldbrk,
 			 struct list_head *uf)
 {
@@ -2981,14 +2981,14 @@ static int do_brk_munmap(struct ma_state *mas, stru=
ct vm_area_struct *vma,
 	int ret;
=20
 	arch_unmap(mm, newbrk, oldbrk);
-	ret =3D do_mas_align_munmap(mas, vma, mm, newbrk, oldbrk, uf, true);
+	ret =3D do_mas_align_munmap(&vmi->mas, vma, mm, newbrk, oldbrk, uf, true)=
;
 	validate_mm_mt(mm);
 	return ret;
 }
=20
 /*
  * do_brk_flags() - Increase the brk vma if the flags match.
- * @mas: The maple tree state.
+ * @vmi: The vma iterator
  * @addr: The start address
  * @len: The length of the increase
  * @vma: The vma,
@@ -2998,7 +2998,7 @@ static int do_brk_munmap(struct ma_state *mas, struct=
 vm_area_struct *vma,
  * do not match then create a new anonymous VMA.  Eventually we may be abl=
e to
  * do some brk-specific accounting here.
  */
-static int do_brk_flags(struct ma_state *mas, struct vm_area_struct *vma,
+static int do_brk_flags(struct vma_iterator *vmi, struct vm_area_struct *v=
ma,
 		unsigned long addr, unsigned long len, unsigned long flags)
 {
 	struct mm_struct *mm =3D current->mm;
@@ -3025,8 +3025,7 @@ static int do_brk_flags(struct ma_state *mas, struct =
vm_area_struct *vma,
 	if (vma && vma->vm_end =3D=3D addr && !vma_policy(vma) &&
 	    can_vma_merge_after(vma, flags, NULL, NULL,
 				addr >> PAGE_SHIFT, NULL_VM_UFFD_CTX, NULL)) {
-		mas_set_range(mas, vma->vm_start, addr + len - 1);
-		if (mas_preallocate(mas, vma, GFP_KERNEL))
+		if (vma_iter_prealloc(vmi, vma))
 			goto unacct_fail;
=20
 		vma_adjust_trans_huge(vma, vma->vm_start, addr + len, 0);
@@ -3036,7 +3035,7 @@ static int do_brk_flags(struct ma_state *mas, struct =
vm_area_struct *vma,
 		}
 		vma->vm_end =3D addr + len;
 		vma->vm_flags |=3D VM_SOFTDIRTY;
-		mas_store_prealloc(mas, vma);
+		vma_iter_store(vmi, vma);
=20
 		if (vma->anon_vma) {
 			anon_vma_interval_tree_post_update_vma(vma);
@@ -3057,8 +3056,8 @@ static int do_brk_flags(struct ma_state *mas, struct =
vm_area_struct *vma,
 	vma->vm_pgoff =3D addr >> PAGE_SHIFT;
 	vma->vm_flags =3D flags;
 	vma->vm_page_prot =3D vm_get_page_prot(flags);
-	mas_set_range(mas, vma->vm_start, addr + len - 1);
-	if (mas_store_gfp(mas, vma, GFP_KERNEL))
+	mas_set_range(&vmi->mas, vma->vm_start, vma->vm_end - 1);
+	if (vma_iter_store_gfp(vmi, vma, GFP_KERNEL))
 		goto mas_store_fail;
=20
 	mm->map_count++;
@@ -3087,7 +3086,7 @@ int vm_brk_flags(unsigned long addr, unsigned long re=
quest, unsigned long flags)
 	int ret;
 	bool populate;
 	LIST_HEAD(uf);
-	MA_STATE(mas, &mm->mm_mt, addr, addr);
+	VMA_ITERATOR(vmi, mm, addr);
=20
 	len =3D PAGE_ALIGN(request);
 	if (len < request)
@@ -3106,12 +3105,12 @@ int vm_brk_flags(unsigned long addr, unsigned long =
request, unsigned long flags)
 	if (ret)
 		goto limits_failed;
=20
-	ret =3D do_mas_munmap(&mas, mm, addr, len, &uf, 0);
+	ret =3D do_mas_munmap(&vmi.mas, mm, addr, len, &uf, 0);
 	if (ret)
 		goto munmap_failed;
=20
-	vma =3D mas_prev(&mas, 0);
-	ret =3D do_brk_flags(&mas, vma, addr, len, flags);
+	vma =3D vma_prev(&vmi);
+	ret =3D do_brk_flags(&vmi, vma, addr, len, flags);
 	populate =3D ((mm->def_flags & VM_LOCKED) !=3D 0);
 	mmap_write_unlock(mm);
 	userfaultfd_unmap_complete(mm, &uf);
--=20
2.35.1