The patch titled
Subject: mm/mmap: preallocate maple nodes for brk vma expansion
has been added to the -mm mm-unstable branch. Its filename is
mm-mmap-preallocate-maple-nodes-for-brk-vma-expansion.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-mmap-preallocate-maple-nodes-for-brk-vma-expansion.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Liam Howlett <liam.howlett@xxxxxxxxxx>
Subject: mm/mmap: preallocate maple nodes for brk vma expansion
Date: Tue, 11 Oct 2022 16:08:37 +0000
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().
Link: https://lkml.kernel.org/r/20221011160624.1253454-1-Liam.Howlett@xxxxxxxxxx
Fixes: 2e7ce7d354f2 (mm/mmap: change do_brk_flags() to expand existing VMA and add do_brk_munmap())
Signed-off-by: Liam R. Howlett <Liam.Howlett@xxxxxxxxxx>
Reported-by: Yu Zhao <yuzhao@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/mmap.c | 18 ++++++------------
1 file changed, 6 insertions(+), 12 deletions(-)
--- a/mm/mmap.c~mm-mmap-preallocate-maple-nodes-for-brk-vma-expansion
+++ a/mm/mmap.c
@@ -2942,17 +2942,18 @@ static int do_brk_flags(struct ma_state
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 @@ mas_store_fail:
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)
_
Patches currently in -mm which might be from liam.howlett@xxxxxxxxxx are
mmap-fix-copy_vma-failure-path.patch
mm-mmap-preallocate-maple-nodes-for-brk-vma-expansion.patch
