On 04/09/2018 07:10 AM, Jia-Ju Bai wrote:
> dn_route_init() is never called in atomic context.
> The call chain ending up at dn_route_init() is:
>  dn_route_init() <- decnet_init()
> decnet_init() is only set as a parameter of module_init().
> Despite never getting called from atomic context,
> dn_route_init() calls __get_free_pages() with GFP_ATOMIC,
> which waits busily for allocation.
> GFP_ATOMIC is not necessary and can be replaced with GFP_KERNEL,
> to avoid busy waiting and improve the possibility of sucessful allocation.
> This is found by a static analysis tool named DCNS written by myself.
> And I also manually check it.
> Signed-off-by: Jia-Ju Bai <baijiaju1...@gmail.com>
> net/decnet/dn_route.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
> diff --git a/net/decnet/dn_route.c b/net/decnet/dn_route.c
> index 0bd3afd..59ed12a 100644
> --- a/net/decnet/dn_route.c
> +++ b/net/decnet/dn_route.c
> @@ -1898,7 +1898,7 @@ void __init dn_route_init(void)
> while(dn_rt_hash_mask & (dn_rt_hash_mask - 1))
> dn_rt_hash_table = (struct dn_rt_hash_bucket *)
> - __get_free_pages(GFP_ATOMIC, order);
> + __get_free_pages(GFP_KERNEL, order);
> } while (dn_rt_hash_table == NULL && --order > 0);
> if (!dn_rt_hash_table)
This might OOM under pressure.
This would need __GFP_NOWARN | __GFP_NORETRY I guess, and would target net-next