The patch titled
Subject: mm/mremap: fix memory account on do_munmap() failure
has been added to the -mm tree. Its filename is
mm-mremap-fix-memory-account-on-do_munmap-failure.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/mm-mremap-fix-memory-account-on-do_munmap-failure.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/mm-mremap-fix-memory-account-on-do_munmap-failure.patch
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------------------------------------------------------
From: Chen Wandun <chenwandun@xxxxxxxxxx>
Subject: mm/mremap: fix memory account on do_munmap() failure
mremap will account the delta between new_len and old_len in
vma_to_resize, and then call move_vma when expanding an existing memory
mapping. In function move_vma, there are two scenarios when calling
do_munmap:
1. move_page_tables from old_addr to new_addr success
2. move_page_tables from old_addr to new_addr fail
In first scenario, it should account old_len if do_munmap fail, because
the delta has already been accounted.
In second scenario, new_addr/new_len will assign to old_addr/old_len if
move_page_table fail, so do_munmap is try to unmap new_addr actually, if
do_munmap fail, it should account the new_len, because error code will be
return from move_vma, and delta will be unaccounted. What'more, because
of new_len == old_len, so account old_len also is OK.
In summary, account old_len will be correct if do_munmap fail.
Link: https://lkml.kernel.org/r/20210717101942.120607-1-chenwandun@xxxxxxxxxx
Fixes: 51df7bcb6151 ("mm/mremap: account memory on do_munmap() failure")
Signed-off-by: Chen Wandun <chenwandun@xxxxxxxxxx>
Cc: Dmitry Safonov <0x7f454c46@xxxxxxxxx>
Cc: Kefeng Wang <wangkefeng.wang@xxxxxxxxxx>
Cc: Wei Yongjun <weiyongjun1@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/mremap.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/mm/mremap.c~mm-mremap-fix-memory-account-on-do_munmap-failure
+++ a/mm/mremap.c
@@ -686,7 +686,7 @@ static unsigned long move_vma(struct vm_
if (do_munmap(mm, old_addr, old_len, uf_unmap) < 0) {
/* OOM: unable to split vma, just get accounts right */
if (vm_flags & VM_ACCOUNT && !(flags & MREMAP_DONTUNMAP))
- vm_acct_memory(new_len >> PAGE_SHIFT);
+ vm_acct_memory(old_len >> PAGE_SHIFT);
excess = 0;
}
_
Patches currently in -mm which might be from chenwandun@xxxxxxxxxx are
mm-mremap-fix-memory-account-on-do_munmap-failure.patch
mm-vmalloc-fix-wrong-behavior-in-vread.patch
