From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx152.postini.com [74.125.245.152]) by kanga.kvack.org (Postfix) with SMTP id E1AC46B002B for ; Thu, 27 Dec 2012 17:27:13 -0500 (EST) Received: by mail-ea0-f179.google.com with SMTP id i12so3998741eaa.38 for ; Thu, 27 Dec 2012 14:27:12 -0800 (PST) MIME-Version: 1.0 In-Reply-To: References: <1356293711-23864-1-git-send-email-sasha.levin@oracle.com> <1356293711-23864-2-git-send-email-sasha.levin@oracle.com> Date: Fri, 28 Dec 2012 00:27:11 +0200 Message-ID: Subject: Re: [PATCH 2/3] mm, bootmem: panic in bootmem alloc functions even if slab is available From: Pekka Enberg Content-Type: text/plain; charset=ISO-8859-1 Sender: owner-linux-mm@kvack.org List-ID: To: David Rientjes Cc: Sasha Levin , Andrew Morton , Johannes Weiner , "David S. Miller" , Tejun Heo , Joonsoo Kim , Yinghai Lu , linux-mm@kvack.org, linux-kernel@vger.kernel.org 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); >> } On Fri, Dec 28, 2012 at 12:25 AM, David Rientjes wrote: > 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? I'm not sure what Sasha's patch is trying to do here but the fall-back is there simply to let the caller know it's calling the bootmem allocator *too late*. That is, the slab allocator is already up and running so you're expected to use that. Pekka -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org