Re: [PATCH 2/5] proc: use down_read_killable for /proc/pid/smaps_rollup

Michal Hocko
2019-05-17T12:45:59Z

On Wed 15-05-19 11:41:14, Konstantin Khlebnikov wrote:
> Ditto.

Proper changelog or simply squash those patches into a single patch if
you do not feel like copy&paste is fun

>
> Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
> ---
> fs/proc/task_mmu.c | 8 ++++++--
> 1 file changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
> index 2bf210229daf..781879a91e3b 100644
> --- a/fs/proc/task_mmu.c
> +++ b/fs/proc/task_mmu.c
> @@ -832,7 +832,10 @@ static int show_smaps_rollup(struct seq_file *m, void *v)
>
> memset(&mss, 0, sizeof(mss));
>
> - down_read(&mm->mmap_sem);
> + ret = down_read_killable(&mm->mmap_sem);
> + if (ret)
> + goto out_put_mm;

Why not ret = -EINTR. The seq_file code seems to be handling all errors
AFAICS.

> +
> hold_task_mempolicy(priv);
>
> for (vma = priv->mm->mmap; vma; vma = vma->vm_next) {
> @@ -849,8 +852,9 @@ static int show_smaps_rollup(struct seq_file *m, void *v)
>
> release_task_mempolicy(priv);
> up_read(&mm->mmap_sem);
> - mmput(mm);
>
> +out_put_mm:
> + mmput(mm);
> out_put_task:
> put_task_struct(priv->task);
> priv->task = NULL;

--
Michal Hocko
SUSE Labs