Re: [PATCH v2 01/12] uprobes: update outdated comment

Andrii Nakryiko
2024-07-10T15:14:28Z

On Wed, Jul 10, 2024 at 6:33 AM Oleg Nesterov <oleg@redhat.com> wrote:
>
> On 07/03, Oleg Nesterov wrote:
> >
> > > /*
> > > - * The NULL 'tsk' here ensures that any faults that occur here
> > > - * will not be accounted to the task. 'mm' *is* current->mm,
> > > - * but we treat this as a 'remote' access since it is
> > > - * essentially a kernel access to the memory.
> > > + * 'mm' *is* current->mm, but we treat this as a 'remote' access since
> > > + * it is essentially a kernel access to the memory.
> > > */
> > > result = get_user_pages_remote(mm, vaddr, 1, FOLL_FORCE, &page, NULL);
> >
> > OK, this makes it less confusing, so
> >
> > Acked-by: Oleg Nesterov <oleg@redhat.com>
> >
> > ---------------------------------------------------------------------
> > but it still looks confusing to me. This code used to pass tsk = NULL
> > only to avoid tsk->maj/min_flt++ in faultin_page().
> >
> > But today mm_account_fault() increments these counters without checking
> > FAULT_FLAG_REMOTE, mm == current->mm, so it seems it would be better to
> > just use get_user_pages() and remove this comment?
>
> Well, yes, it still looks confusing, imo.
>
> Andrii, I hope you won't mind if I redo/resend this and the next cleanup?
>
> The next one only updates the comment above uprobe_write_opcode(), but
> it would be nice to explain mmap_write_lock() in register_for_each_vma().
>

I don't mind a bit, thanks for sending the patches!

> Oleg.
>
>