Re: [PATCH] oom_reaper: switch to struct list_head for reap queue

Johannes Weiner
2017-02-14T16:30:49Z

On Wed, Feb 15, 2017 at 02:07:14AM +1100, Aleksa Sarai wrote:
> Rather than implementing an open addressing linked list structure
> ourselves, use the standard list_head structure to improve consistency
> with the rest of the kernel and reduce confusion.
>
> Cc: Michal Hocko <mhocko@suse.com>
> Cc: Oleg Nesterov <oleg@redhat.com>
> Signed-off-by: Aleksa Sarai <asarai@suse.de>
> ---
> include/linux/sched.h | 6 +++++-
> kernel/fork.c | 4 ++++
> mm/oom_kill.c | 24 +++++++++++++-----------
> 3 files changed, 22 insertions(+), 12 deletions(-)
>
> diff --git a/include/linux/sched.h b/include/linux/sched.h
> index e93594b88130..d8bcd0f8c5fe 100644
> --- a/include/linux/sched.h
> +++ b/include/linux/sched.h
> @@ -1960,7 +1960,11 @@ struct task_struct {
> #endif
> int pagefault_disabled;
> #ifdef CONFIG_MMU
> - struct task_struct *oom_reaper_list;
> + /*
> + * List of threads that have to be reaped by OOM (rooted at
> + * &oom_reaper_list in mm/oom_kill.c).
> + */
> + struct list_head oom_reaper_list;

This is an extra pointer to task_struct and more lines of code to
accomplish the same thing. Why would we want to do that?