Re: [RFC PATCH v2 04/11] mm: khugepaged: add shmem mTHP collapse support

[Baolin Wang]

On 6/10/26 8:13 PM, Lance Yang wrote:
> On Wed, Jun 10, 2026 at 06:29:12PM +0800, Baolin Wang wrote:
> [...]
> > @@ -2808,7 +2875,7 @@ static enum scan_result collapse_single_pmd(unsigned long addr,
> > 	mmap_read_unlock(mm);
> > 	*lock_dropped = true;
> > retry:
> > -	result = collapse_scan_file(mm, addr, file, pgoff, cc);
> > +	result = collapse_scan_file(mm, vma, addr, file, pgoff, cc);
>
> Looks unsafe to pass "vma" down here, since we have already dropped
> mmap_read_unlock(mm) ...
>
> A racing munmap() could leave it stale before collapse_scan_file() use
> it, no?

Good catch. Sashiko also complained about this issue. Will fix.