[PATCH v7 41/70] coredump: Remove vma linked list walk

Liam Howlett
2022-04-04T14:40:12Z

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.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
---
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_struct *vma,
return vma->vm_end - vma->vm_start;
}

-static struct vm_area_struct *first_vma(struct task_struct *tsk,
- struct vm_area_struct *gate_vma)
-{
- struct vm_area_struct *ret = tsk->mm->mmap;
-
- if (ret)
- return ret;
- return gate_vma;
-}
-
/*
* Helper function for iterating across a vma list. It ensures that the caller
* 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 = this_vma->vm_next;
- if (ret)
- return ret;
- if (this_vma == gate_vma)
+ if (gate_vma && (vma == gate_vma))
return NULL;
+
+ vma = mas_next(mas, ULONG_MAX);
+ if (vma)
+ return vma;
return gate_vma;
}

@@ -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 = NULL;
struct mm_struct *mm = current->mm;
- int i;
+ MA_STATE(mas, &mm->mm_mt, 0, 0);
+ int i = 0;

/*
* 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;
}

- for (i = 0, vma = first_vma(current, gate_vma); vma != NULL;
- vma = next_vma(vma, gate_vma), i++) {
+ while ((vma = coredump_next_vma(&mas, vma, gate_vma)) != NULL) {
struct core_vma_metadata *m = cprm->vma_meta + i;

m->start = vma->vm_start;
@@ -1150,10 +1140,10 @@ static bool dump_vma_snapshot(struct coredump_params *cprm)
m->flags = vma->vm_flags;
m->dump_size = vma_dump_size(vma, cprm->mm_flags);
m->pgoff = vma->vm_pgoff;
-
m->file = vma->vm_file;
if (m->file)
get_file(m->file);
+ i++;
}

mmap_write_unlock(mm);
--
2.34.1