Re: [PATCH] mm/memory: Return vm_fault_t result from migrate_to_ram() callback

[David Hildenbrand <david@redhat.com>]

On 14.11.22 12:55, Alistair Popple wrote:
> The migrate_to_ram() callback should always succeed, but in rare cases
> can fail usually returning VM_FAULT_SIGBUS. Commit 16ce101db85d
> ("mm/memory.c: fix race when faulting a device private page")
> incorrectly stopped passing the return code up the stack. Fix this by
> setting the ret variable, restoring the previous behaviour on
> migrate_to_ram() failure.
> 
> Fixes: 16ce101db85d ("mm/memory.c: fix race when faulting a device private page")
> Signed-off-by: Alistair Popple <apopple@nvidia.com>
> Cc: Ralph Campbell <rcampbell@nvidia.com>
> Cc: John Hubbard <jhubbard@nvidia.com>
> Cc: Alex Sierra <alex.sierra@amd.com>
> Cc: Ben Skeggs <bskeggs@redhat.com>
> Cc: Felix Kuehling <Felix.Kuehling@amd.com>
> Cc: Lyude Paul <lyude@redhat.com>
> Cc: Jason Gunthorpe <jgg@nvidia.com>
> Cc: Michael Ellerman <mpe@ellerman.id.au>
> 
> ---
> 
> Hi Andrew, I noticed my series needs another small fix which I'm
> hoping you can apply for v6.1-rcX. Thanks (and sorry for not catching
> this sooner).
> ---
>   mm/memory.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/mm/memory.c b/mm/memory.c
> index f88c351aecd4..8a6d5c823f91 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -3763,7 +3763,7 @@ vm_fault_t do_swap_page(struct vm_fault *vmf)
>   			 */
>   			get_page(vmf->page);
>   			pte_unmap_unlock(vmf->pte, vmf->ptl);
> -			vmf->page->pgmap->ops->migrate_to_ram(vmf);
> +			ret = vmf->page->pgmap->ops->migrate_to_ram(vmf);
>   			put_page(vmf->page);
>   		} else if (is_hwpoison_entry(entry)) {
>   			ret = VM_FAULT_HWPOISON;


Acked-by: David Hildenbrand <david@redhat.com>

-- 
Thanks,

David / dhildenb