Re: [PATCH 1/3] shmem: fix double uncharge in __shmem_file_setup()

Hugh Dickins
2014-06-26T03:45:54Z

On Wed, 25 Jun 2014, Konstantin Khlebnikov wrote:

> If __shmem_file_setup() fails on struct file allocation it uncharges memory
> commitment twice: first by shmem_unacct_size() and second time implicitly in
> shmem_evict_inode() when it kills newly created inode.
> This patch removes shmem_unacct_size() from error path if inode already here.
>
> Signed-off-by: Konstantin Khlebnikov <koct9i@gmail.com>

Acked-by: Hugh Dickins <hughd@google.com>

Thank you for the patch, and thank you for your patience (or perhaps for
your kindly concealed impatience): I realize that this (and the other two)
have been languishing in the must-get-to-look-at-it-sometime end of my
mailbox for nine months now - sorry.

> ---
> mm/shmem.c | 12 ++++++------
> 1 file changed, 6 insertions(+), 6 deletions(-)
>
> diff --git a/mm/shmem.c b/mm/shmem.c
> index 8f419cf..0aabcbd 100644
> --- a/mm/shmem.c
> +++ b/mm/shmem.c
> @@ -2895,16 +2895,16 @@ static struct file *__shmem_file_setup(const char *name, loff_t size,
> this.len = strlen(name);
> this.hash = 0; /* will go */
> sb = shm_mnt->mnt_sb;
> + path.mnt = mntget(shm_mnt);
> path.dentry = d_alloc_pseudo(sb, &this);
> if (!path.dentry)
> goto put_memory;
> d_set_d_op(path.dentry, &anon_ops);
> - path.mnt = mntget(shm_mnt);
>
> res = ERR_PTR(-ENOSPC);
> inode = shmem_get_inode(sb, NULL, S_IFREG | S_IRWXUGO, 0, flags);
> if (!inode)
> - goto put_dentry;
> + goto put_memory;
>
> inode->i_flags |= i_flags;
> d_instantiate(path.dentry, inode);
> @@ -2912,19 +2912,19 @@ static struct file *__shmem_file_setup(const char *name, loff_t size,
> clear_nlink(inode); /* It is unlinked */
> res = ERR_PTR(ramfs_nommu_expand_for_mapping(inode, size));
> if (IS_ERR(res))
> - goto put_dentry;
> + goto put_path;
>
> res = alloc_file(&path, FMODE_WRITE | FMODE_READ,
> &shmem_file_operations);
> if (IS_ERR(res))
> - goto put_dentry;
> + goto put_path;
>
> return res;
>
> -put_dentry:
> - path_put(&path);
> put_memory:
> shmem_unacct_size(flags, size);
> +put_path:
> + path_put(&path);
> return res;
> }
>