On Thu, Aug 28, 2025 at 7:11 PM Lorenzo Stoakes
[off-list ref] wrote:

On Thu, Aug 28, 2025 at 02:12:12PM +0800, Yafang Shao wrote:

quoted

On Wed, Aug 27, 2025 at 11:46 PM Lorenzo Stoakes
[off-list ref] wrote:

quoted

On Tue, Aug 26, 2025 at 03:19:42PM +0800, Yafang Shao wrote:

quoted

Every VMA must have an associated mm_struct, and it is safe to access

Err this isn't true? Pretty sure special VMAs don't have that set.

I’m not aware of any VMA that doesn’t belong to an mm_struct. If there
is such a case, it would be helpful if you could point it out. In any
case, I’ll remove the VMA-related code in the next version since it’s
unnecessary.

If you lok at get_vma_name() in fs/proc/task_mmu.c you'll see:

        if (!vma->vm_mm) {
                *name = "[vdso]";
                return;
        }

So a VDSO will have this condition.

I did a quick drgn()/printk() test and didn't see any, but maybe my system - but
in any case this appears to be a valid situation that can arise, presumably
because it's a VMA somehow shared with multiple mm's or something truly god
awful like that :)

Thanks for clarifying that.

-- 
Regards
Yafang