Re: BUG_ON() in pfn_swap_entry_to_page()

[David Hildenbrand <david@redhat.com>]

On 24.04.24 21:45, Felix Kuehling wrote:
> Sorry for top-posting. I'm resurrecting an old thread here because I 
> think I ran into the same problem with this assertion failing on Linux 6.7:
> 
> static inline struct page *pfn_swap_entry_to_page(swp_entry_t entry)
> {
>          struct page *p = pfn_to_page(swp_offset_pfn(entry));
> 
>          /*
>           * Any use of migration entries may only occur while the
>           * corresponding page is locked
>           */
> -->     BUG_ON(is_migration_entry(entry) && !PageLocked(p));
> 
>          return p;
> }
> 
> It looks like this thread just fizzled two years ago. Did anything ever 
> come of this?
> 
> Maybe I should add that I saw this in a pre-silicon test environment. 
> I've never seen this on real hardware. Maybe something timing-sensitive.

In the past, it indicated a swp pte corruption, that would e.g., mess up 
the stored PFN ot the swap entry type.

On which call chain do you see that?

-- 
Cheers,

David / dhildenb