If the brk VMA is the last vma in a maple node and meets the rare
criteria that it can be expanded, then preallocation is necessary to
avoid a potential fs_reclaim circular lock issue on low resources.
At the same time use the actual vma start address (unaligned) when
calling vma_adjust_trans_huge().
Fixes: 2e7ce7d354f2 (mm/mmap: change do_brk_flags() to expand existing VMA and add do_brk_munmap())
Reported-by: Yu Zhao <yuzhao@xxxxxxxxxx>
Signed-off-by: Liam R. Howlett <Liam.Howlett@xxxxxxxxxx>
---
mm/mmap.c | 18 ++++++------------
1 file changed, 6 insertions(+), 12 deletions(-)
diff --git a/mm/mmap.c b/mm/mmap.c
index 6e447544f07d..74c0e3784500 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -2942,17 +2942,18 @@ static int do_brk_flags(struct ma_state *mas, struct vm_area_struct *vma,
if (vma &&
(!vma->anon_vma || list_is_singular(&vma->anon_vma_chain)) &&
((vma->vm_flags & ~VM_SOFTDIRTY) == flags)) {
- mas->index = vma->vm_start;
- mas->last = addr + len - 1;
- vma_adjust_trans_huge(vma, addr, addr + len, 0);
+ mas_set_range(mas, vma->vm_start, addr + len - 1);
+ if (mas_preallocate(mas, vma, GFP_KERNEL))
+ return -ENOMEM;
+
+ vma_adjust_trans_huge(vma, vma->vm_start, addr + len, 0);
if (vma->anon_vma) {
anon_vma_lock_write(vma->anon_vma);
anon_vma_interval_tree_pre_update_vma(vma);
}
vma->vm_end = addr + len;
vma->vm_flags |= VM_SOFTDIRTY;
- if (mas_store_gfp(mas, vma, GFP_KERNEL))
- goto mas_expand_failed;
+ mas_store_prealloc(mas, vma);
if (vma->anon_vma) {
anon_vma_interval_tree_post_update_vma(vma);
@@ -2993,13 +2994,6 @@ static int do_brk_flags(struct ma_state *mas, struct vm_area_struct *vma,
vma_alloc_fail:
vm_unacct_memory(len >> PAGE_SHIFT);
return -ENOMEM;
-
-mas_expand_failed:
- if (vma->anon_vma) {
- anon_vma_interval_tree_post_update_vma(vma);
- anon_vma_unlock_write(vma->anon_vma);
- }
- return -ENOMEM;
}
int vm_brk_flags(unsigned long addr, unsigned long request, unsigned long flags)
--
2.35.1
