Re: [PATCH] mm/shmem.c: Fix the missing unaccount on the failed path
From: Tianjia Zhang
Date: Tue Sep 22 2020 - 01:27:33 EST
On 9/21/20 2:49 AM, Hugh Dickins wrote:
On Mon, 21 Sep 2020, Tianjia Zhang wrote:
In function __shmem_file_setup(), shmem_unacct_size() is forgotten
on the failed path, so add it.
Fixes: 93dec2da7b234 ("... and switch shmem_file_setup() to alloc_file_pseudo()")
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Tianjia Zhang <tianjia.zhang@xxxxxxxxxxxxxxxxx>
---
mm/shmem.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/mm/shmem.c b/mm/shmem.c
index 8e2b35ba93ad..591410dc3541 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -4200,8 +4200,10 @@ static struct file *__shmem_file_setup(struct vfsmount *mnt, const char *name, l
if (!IS_ERR(res))
res = alloc_file_pseudo(inode, mnt, name, O_RDWR,
&shmem_file_operations);
- if (IS_ERR(res))
+ if (IS_ERR(res)) {
iput(inode);
+ shmem_unacct_size(flags, size);
+ }
return res;
}
--
2.19.1.3.ge56e4f7
Looks mistaken to me.
Is this something you noticed by source inspection,
or something you have observed in practice?
I haven't tried exercising this path while injecting errors into
alloc_file_pseudo(); but what I'd expect to happen is that the
iput(inode), which you see already on that error path, will get
to evict the inode, which will entail calling shmem_evict_inode(),
which does that shmem_unacct_size() itself.
Hugh
I noticed by looking at the code. you are right, I neglected this point,
thanks for your explanation.
Thanks,
Tianjia