Re: [PATCH 1/3] mm: Check if mmu notifier callbacks are allowed to fail

[Koenig, Christian]

Am 22.11.18 um 17:51 schrieb Daniel Vetter:
> Just a bit of paranoia, since if we start pushing this deep into
> callchains it's hard to spot all places where an mmu notifier
> implementation might fail when it's not allowed to.
>
> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> Cc: Michal Hocko <mhocko@xxxxxxxx>
> Cc: "Christian KÃnig" <christian.koenig@xxxxxxx>
> Cc: David Rientjes <rientjes@xxxxxxxxxx>
> Cc: Daniel Vetter <daniel.vetter@xxxxxxxx>
> Cc: "JÃrÃme Glisse" <jglisse@xxxxxxxxxx>
> Cc: linux-mm@xxxxxxxxx
> Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx>
> Signed-off-by: Daniel Vetter <daniel.vetter@xxxxxxxxx>

Acked-by: Christian KÃnig <christian.koenig@xxxxxxx>

> ---
>   mm/mmu_notifier.c | 2 ++
>   1 file changed, 2 insertions(+)
>
> diff --git a/mm/mmu_notifier.c b/mm/mmu_notifier.c
> index 5119ff846769..59e102589a25 100644
> --- a/mm/mmu_notifier.c
> +++ b/mm/mmu_notifier.c
> @@ -190,6 +190,8 @@ int __mmu_notifier_invalidate_range_start(struct mm_struct *mm,
>   				pr_info("%pS callback failed with %d in %sblockable context.\n",
>   						mn->ops->invalidate_range_start, _ret,
>   						!blockable ? "non-" : "");
> +				WARN(blockable,"%pS callback failure not allowed\n",
> +				     mn->ops->invalidate_range_start);
>   				ret = _ret;
>   			}
>   		}