mm/mmap: abstract vma clean up from exit_mmap()

Create the new function tear_down_vmas() to remove a range of vmas.
exit_mmap() will be removing all the vmas.

This is necessary for future patches.

No functional changes intended.

Link: https://lkml.kernel.org/r/20260121164946.2093480-4-Liam.Howlett@oracle.com
Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Pedro Falcato <pfalcato@suse.de>
Reviewed-by: Suren Baghdasaryan <surenb@google.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Chris Li <chrisl@kernel.org>
Cc: David Hildenbrand <david@kernel.org>
Cc: Jann Horn <jannh@google.com>
Cc: Kairui Song <kasong@tencent.com>
Cc: Kemeng Shi <shikemeng@huaweicloud.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: SeongJae Park <sj@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/mmap.c b/mm/mmap.c
index 1f025edf8d7d07d43c8f0768305d00d1c49c20e6..9c8adc505d3de0b609c9c4c49dcfa007e180398f 100644 (file)
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1247,6 +1247,29 @@ limits_failed:
 }
 EXPORT_SYMBOL(vm_brk_flags);
 
+static
+unsigned long tear_down_vmas(struct mm_struct *mm, struct vma_iterator *vmi,
+               struct vm_area_struct *vma, unsigned long end)
+{
+       unsigned long nr_accounted = 0;
+       int count = 0;
+
+       mmap_assert_write_locked(mm);
+       vma_iter_set(vmi, vma->vm_end);
+       do {
+               if (vma->vm_flags & VM_ACCOUNT)
+                       nr_accounted += vma_pages(vma);
+               vma_mark_detached(vma);
+               remove_vma(vma);
+               count++;
+               cond_resched();
+               vma = vma_next(vmi);
+       } while (vma && vma->vm_end <= end);
+
+       VM_WARN_ON_ONCE(count != mm->map_count);
+       return nr_accounted;
+}
+
 /* Release all mmaps. */
 void exit_mmap(struct mm_struct *mm)
 {
@@ -1254,7 +1277,6 @@ void exit_mmap(struct mm_struct *mm)
        struct vm_area_struct *vma;
        unsigned long nr_accounted = 0;
        VMA_ITERATOR(vmi, mm, 0);
-       int count = 0;
 
        /* mm's last user has gone, and its about to be pulled down */
        mmu_notifier_release(mm);
@@ -1294,18 +1316,7 @@ void exit_mmap(struct mm_struct *mm)
         * enabled, without holding any MM locks besides the unreachable
         * mmap_write_lock.
         */
-       vma_iter_set(&vmi, vma->vm_end);
-       do {
-               if (vma->vm_flags & VM_ACCOUNT)
-                       nr_accounted += vma_pages(vma);
-               vma_mark_detached(vma);
-               remove_vma(vma);
-               count++;
-               cond_resched();
-               vma = vma_next(&vmi);
-       } while (vma && likely(!xa_is_zero(vma)));
-
-       BUG_ON(count != mm->map_count);
+       nr_accounted = tear_down_vmas(mm, &vmi, vma, ULONG_MAX);
 
 destroy:
        __mt_destroy(&mm->mm_mt);