Re: [PATCH v2 0/2] mm/gup: stop leaking pinned pages in low memory conditions

[John Hubbard <jhubbard@nvidia.com>]

On 10/18/24 3:13 PM, Andrew Morton wrote:
> On Thu, 17 Oct 2024 18:17:09 -0700 John Hubbard <jhubbard@nvidia.com> wrote:
> 
> I added cc:stable to both of these.  Which might be inappropriate since
> "patch #2 is not really required".

Right.

> 
>>    mm/gup: stop leaking pinned pages in low memory conditions
> 
> Fixes: 24a95998e9ba ("mm/gup.c: simplify and fix check_and_migrate_movable_pages() return codes")
> 
> In mainline since v6.1!
> 
>>    mm/gup: memfd: stop leaking pinned pages in low memory conditions
> 
> Fixes: 89c1905d9c14 ("mm/gup: introduce memfd_pin_folios() for pinning memfd folios")
> 
> Since v6.11.
> 
> 
> So these are quite independent fixes.  Kernels 6.1.x ...  6.10.x will
> have the first patch and not the second.  That's presumably an untested
> combination, fingers crossed.
> 

Probably fine.

> 

Ah, I'm actually about to send out v3 in a moment, which only has one patch,
whose diffs are just comment changes, plus David's latest suggestion:


  static long check_and_migrate_movable_pages(unsigned long nr_pages,
                                             struct page **pages)
@@ -2437,8 +2440,10 @@ static long check_and_migrate_movable_pages(unsigned long nr_pages,
         long i, ret;
  
         folios = kmalloc_array(nr_pages, sizeof(*folios), GFP_KERNEL);
-       if (!folios)
+       if (!folios) {
+               unpin_user_pages(pages, nr_pages);
                 return -ENOMEM;
+       }
  
         for (i = 0; i < nr_pages; i++)
                 folios[i] = page_folio(pages[i]);


thanks,
-- 
John Hubbard