coredump: remove vma linked list walk

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/20220906194824.2110408-41-Liam.Howlett@oracle.com
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Tested-by: Yu Zhao <yuzhao@google.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: SeongJae Park <sj@kernel.org>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/fs/coredump.c b/fs/coredump.c
index 9f4aae2..35f2af8 100644 (file)
--- a/fs/coredump.c
+++ b/fs/coredump.c
@@ -1072,30 +1072,20 @@ whole:
        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);