linux-kernel - Re: [PATCH 2/3] mm, bootmem: panic in bootmem alloc functions even if slab is available

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 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:	Thu, 27 Dec 2012 14:25:12 -0800 (PST)
From:	David Rientjes <rientjes@...gle.com>
To:	Sasha Levin <sasha.levin@...cle.com>
cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Johannes Weiner <hannes@...xchg.org>,
	"David S. Miller" <davem@...emloft.net>, Tejun Heo <tj@...nel.org>,
	Joonsoo Kim <js1304@...il.com>,
	Yinghai Lu <yinghai@...nel.org>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/3] mm, bootmem: panic in bootmem alloc functions even
 if slab is available

On Sun, 23 Dec 2012, Sasha Levin wrote:

> diff --git a/mm/bootmem.c b/mm/bootmem.c
> index 1324cd7..198a92f 100644
> --- a/mm/bootmem.c
> +++ b/mm/bootmem.c
> @@ -763,9 +763,6 @@ void * __init ___alloc_bootmem_node(pg_data_t *pgdat, unsigned long size,
>  void * __init __alloc_bootmem_node(pg_data_t *pgdat, unsigned long size,
>  				   unsigned long align, unsigned long goal)
>  {
> -	if (WARN_ON_ONCE(slab_is_available()))
> -		return kzalloc_node(size, GFP_NOWAIT, pgdat->node_id);
> -
>  	return  ___alloc_bootmem_node(pgdat, size, align, goal, 0);
>  }
>  

All you're doing is removing the fallback if this happens to be called 
with slab_is_available().  It's still possible that the slab allocator can 
successfully allocate the memory, though.  So it would be rather 
unfortunate to start panicking in a situation that used to only emit a 
warning.

Why can't you panic only kzalloc_node() returns NULL and otherwise just 
return the allocated memory?
--
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/