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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>,
        Hugh Dickins <hughd@google.com>
CC:     Yu Zhao <yuzhao@google.com>
Subject: [PATCH v12 40/69] coredump: remove vma linked list walk
Thread-Topic: [PATCH v12 40/69] coredump: remove vma linked list walk
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Date:   Wed, 20 Jul 2022 02:17:56 +0000
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From: "Matthew Wilcox (Oracle)" <willy@infradead.org>

Use the Maple Tree iterator instead.  This is too complicated for the VMA
iterator to handle, so let's open-code it for now.  If this turns out to
be a common pattern, we can migrate it to common code.

Link: https://lkml.kernel.org/r/20220504011345.662299-25-Liam.Howlett@oracl=
e.com
Link: https://lkml.kernel.org/r/20220621204632.3370049-41-Liam.Howlett@orac=
le.com
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: David Howells <dhowells@redhat.com>
Cc: SeongJae Park <sj@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Will Deacon <will@kernel.org>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
 fs/coredump.c | 34 ++++++++++++----------------------
 1 file changed, 12 insertions(+), 22 deletions(-)

diff --git a/fs/coredump.c b/fs/coredump.c
index ebc43f960b64..3a0022c1ca36 100644
--- a/fs/coredump.c
+++ b/fs/coredump.c
@@ -1072,30 +1072,20 @@ static unsigned long vma_dump_size(struct vm_area_s=
truct *vma,
 	return vma->vm_end - vma->vm_start;
 }
=20
-static struct vm_area_struct *first_vma(struct task_struct *tsk,
-					struct vm_area_struct *gate_vma)
-{
-	struct vm_area_struct *ret =3D tsk->mm->mmap;
-
-	if (ret)
-		return ret;
-	return gate_vma;
-}
-
 /*
  * Helper function for iterating across a vma list.  It ensures that the c=
aller
  * will visit `gate_vma' prior to terminating the search.
  */
-static struct vm_area_struct *next_vma(struct vm_area_struct *this_vma,
+static struct vm_area_struct *coredump_next_vma(struct ma_state *mas,
+				       struct vm_area_struct *vma,
 				       struct vm_area_struct *gate_vma)
 {
-	struct vm_area_struct *ret;
-
-	ret =3D this_vma->vm_next;
-	if (ret)
-		return ret;
-	if (this_vma =3D=3D gate_vma)
+	if (gate_vma && (vma =3D=3D gate_vma))
 		return NULL;
+
+	vma =3D mas_next(mas, ULONG_MAX);
+	if (vma)
+		return vma;
 	return gate_vma;
 }
=20
@@ -1119,9 +1109,10 @@ static void free_vma_snapshot(struct coredump_params=
 *cprm)
  */
 static bool dump_vma_snapshot(struct coredump_params *cprm)
 {
-	struct vm_area_struct *vma, *gate_vma;
+	struct vm_area_struct *gate_vma, *vma =3D NULL;
 	struct mm_struct *mm =3D current->mm;
-	int i;
+	MA_STATE(mas, &mm->mm_mt, 0, 0);
+	int i =3D 0;
=20
 	/*
 	 * Once the stack expansion code is fixed to not change VMA bounds
@@ -1141,8 +1132,7 @@ static bool dump_vma_snapshot(struct coredump_params =
*cprm)
 		return false;
 	}
=20
-	for (i =3D 0, vma =3D first_vma(current, gate_vma); vma !=3D NULL;
-			vma =3D next_vma(vma, gate_vma), i++) {
+	while ((vma =3D coredump_next_vma(&mas, vma, gate_vma)) !=3D NULL) {
 		struct core_vma_metadata *m =3D cprm->vma_meta + i;
=20
 		m->start =3D vma->vm_start;
@@ -1150,10 +1140,10 @@ static bool dump_vma_snapshot(struct coredump_param=
s *cprm)
 		m->flags =3D vma->vm_flags;
 		m->dump_size =3D vma_dump_size(vma, cprm->mm_flags);
 		m->pgoff =3D vma->vm_pgoff;
-
 		m->file =3D vma->vm_file;
 		if (m->file)
 			get_file(m->file);
+		i++;
 	}
=20
 	mmap_write_unlock(mm);
--=20
2.35.1