Re: [PATCH v4 8/8] mm: support both pid and pidfd for process_madvise

[Alexander Duyck <alexander.h.duyck-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>]

On Wed, 2020-02-12 at 15:39 -0800, Minchan Kim wrote:
> There is a demand[1] to support pid as well pidfd for process_madvise
> to reduce unnecessary syscall to get pidfd if the user has control of
> the target process(ie, they could guarantee the process is not gone
> or pid is not reused. Or, it might be okay to give a hint to wrong
> process).
> 
> This patch aims for supporting both options like waitid(2). So, the
> syscall is currently,
> 
> 	int process_madvise(int which, pid_t pid, void *addr,
> 		size_t length, int advise, unsigned long flag);
> 
> @which is actually idtype_t for userspace libray and currently,
> it supports P_PID and P_PIDFD.
> 
> [1]  https://lore.kernel.org/linux-mm/9d849087-3359-c4ab-fbec-859e8186c509-5HdwGun5lf+gSpxsJD1C4w@public.gmane.org/
> 
> Cc: Christian Brauner <christian-STijNZzMWpgWenYVfaLwtA@public.gmane.org>
> Suggested-by: Kirill Tkhai <ktkhai-5HdwGun5lf+gSpxsJD1C4w@public.gmane.org>
> Signed-off-by: Minchan Kim <minchan-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>

So if you move patch 7 up before patch 2 you could squash this patch with
your current patch 2 and drop one patch from your series. It would
probably help to reduce the review overhead as well.