Re: [PATCH 2/3] kvfree_rcu: Use __GFP_NOMEMALLOC for single-argument kvfree_rcu()

[Uladzislau Rezki]

On Wed, Jan 20, 2021 at 05:21:47PM +0100, Uladzislau Rezki (Sony) wrote:
> From: "Paul E. McKenney" <paulmck@xxxxxxxxxx>
> 
> This commit applies the __GFP_NOMEMALLOC gfp flag to memory allocations
> carried out by the single-argument variant of kvfree_rcu(), thus avoiding
> this can-sleep code path from dipping into the emergency reserves.
> 
> Acked-by: Michal Hocko <mhocko@xxxxxxxx>
> Suggested-by: Michal Hocko <mhocko@xxxxxxxx>
> Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx>
> Signed-off-by: Uladzislau Rezki (Sony) <urezki@xxxxxxxxx>
> ---
>  kernel/rcu/tree.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
> index 2014fb22644d..454809514c91 100644
> --- a/kernel/rcu/tree.c
> +++ b/kernel/rcu/tree.c
> @@ -3491,7 +3491,7 @@ add_ptr_to_bulk_krc_lock(struct kfree_rcu_cpu **krcp,
>  		if (!bnode && can_alloc) {
>  			krc_this_cpu_unlock(*krcp, *flags);
>  			bnode = (struct kvfree_rcu_bulk_data *)
> -				__get_free_page(GFP_KERNEL | __GFP_RETRY_MAYFAIL | __GFP_NOWARN);
> +				__get_free_page(GFP_KERNEL | __GFP_RETRY_MAYFAIL | __GFP_NOMEMALLOC | __GFP_NOWARN);
>  			*krcp = krc_this_cpu_lock(flags);
>  		}
>  
> -- 
> 2.20.1
> 
Please see below a V2:

V1 -> V2:
    - rebase on [PATCH v2 1/1] kvfree_rcu: Directly allocate page for single-argument
    - add a comment about __GFP_NOMEMALLOC usage.

<snip>