linux-kernel - Re: [PATCH] slab: prevent warnings when allocating with __GFP

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Mon, 10 Jun 2013 22:31:15 +0300
From:	Pekka Enberg <penberg@...nel.org>
To:	Sasha Levin <sasha.levin@...cle.com>
Cc:	Christoph Lameter <cl@...ux.com>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] slab: prevent warnings when allocating with __GFP_NOWARN

Hello Sasha,

On Mon, Jun 10, 2013 at 10:18 PM, Sasha Levin <sasha.levin@...cle.com> wrote:
> slab would still spew a warning when a big allocation happens with the
> __GFP_NOWARN fleg is set. Prevent that to conform to __GFP_NOWARN.
>
> Signed-off-by: Sasha Levin <sasha.levin@...cle.com>
> ---
>  mm/slab_common.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/mm/slab_common.c b/mm/slab_common.c
> index ff3218a..2d41450 100644
> --- a/mm/slab_common.c
> +++ b/mm/slab_common.c
> @@ -373,8 +373,10 @@ struct kmem_cache *kmalloc_slab(size_t size, gfp_t flags)
>  {
>         int index;
>
> -       if (WARN_ON_ONCE(size > KMALLOC_MAX_SIZE))
> +       if (size > KMALLOC_MAX_SIZE) {
> +               WARN_ON_ONCE(!(flags & __GFP_NOWARN));
>                 return NULL;
> +       }

Does this fix a real problem you're seeing? __GFP_NOWARN is about not
warning if a memory allocation fails but this particular WARN_ON
suggests a kernel bug.

                         Pekka
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/