Re: [PATCH 5/8] trace_uprobe: Support SDT markers having reference count (semaphore)

[Oleg Nesterov]

On 03/15, Oleg Nesterov wrote:
>
> > +static struct vm_area_struct *
> > +sdt_find_vma(struct mm_struct *mm, struct trace_uprobe *tu)
> > +{
> > +	struct vm_area_struct *tmp;
> > +
> > +	for (tmp = mm->mmap; tmp != NULL; tmp = tmp->vm_next)
> > +		if (sdt_valid_vma(tu, tmp))
> > +			return tmp;
> > +
> > +	return NULL;
>
> I can't understand the logic... Lets ignore sdt_valid_vma() for now.
> The caller has uprobe_map_info, why it can't simply do
> vma = find_vma(uprobe_map_info->vaddr)? and then check sdt_valid_vma().

Note to mention that sdt_find_vma() can return NULL but the callers do
vma_offset_to_vaddr(vma) without any check.

Oleg.