Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933472Ab1CXAUi (ORCPT ); Wed, 23 Mar 2011 20:20:38 -0400 Received: from mx1.redhat.com ([209.132.183.28]:1032 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933023Ab1CXAUh (ORCPT ); Wed, 23 Mar 2011 20:20:37 -0400 Organization: Red Hat UK Ltd. Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 3798903 From: David Howells In-Reply-To: <1300826506-23192-1-git-send-email-vapier@gentoo.org> References: <1300826506-23192-1-git-send-email-vapier@gentoo.org> To: Mike Frysinger , graf.yang@analog.com Cc: dhowells@redhat.com, uclinux-dev@uclinux.org, Greg Ungerer , Paul Mundt , uclinux-dist-devel@blackfin.uclinux.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] NOMMU: support SMP dynamic percpu_alloc Date: Thu, 24 Mar 2011 00:20:12 +0000 Message-ID: <10444.1300926012@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2174 Lines: 58 Mike Frysinger wrote: > The percpu code requires more functions to be implemented in the mm core > which nommu currently does not provide. So add inline implementations > since these are largely meaningless on nommu systems. Under what conditions are these required? I've seen one percpu compilation bug that I've made a patch for (see attached), but none of these. Is SMP required to trigger them? David --- From: David Howells Subject: [PATCH] NOMMU: percpu should use is_vmalloc_addr(). per_cpu_ptr_to_phys() uses VMALLOC_START and VMALLOC_END to determine if an address is in the vmalloc() region or not. This is incorrect on NOMMU as there is no real vmalloc() capability (vmalloc() is emulated by kmalloc()). The correct way to do this is to use is_vmalloc_addr(). This encapsulates the vmalloc() region test in MMU mode and just returns 0 in NOMMU mode. On FRV in NOMMU mode, the percpu compilation fails without this patch: mm/percpu.c: In function 'per_cpu_ptr_to_phys': mm/percpu.c:1011: error: 'VMALLOC_START' undeclared (first use in this function) mm/percpu.c:1011: error: (Each undeclared identifier is reported only once mm/percpu.c:1011: error: for each function it appears in.) mm/percpu.c:1012: error: 'VMALLOC_END' undeclared (first use in this function) mm/percpu.c:1018: warning: control reaches end of non-void function Signed-off-by: David Howells --- mm/percpu.c | 3 +-- 1 files changed, 1 insertions(+), 2 deletions(-) diff --git a/mm/percpu.c b/mm/percpu.c index 3f93001..55d4d11 100644 --- a/mm/percpu.c +++ b/mm/percpu.c @@ -1008,8 +1008,7 @@ phys_addr_t per_cpu_ptr_to_phys(void *addr) } if (in_first_chunk) { - if ((unsigned long)addr < VMALLOC_START || - (unsigned long)addr >= VMALLOC_END) + if (!is_vmalloc_addr(addr)) return __pa(addr); else return page_to_phys(vmalloc_to_page(addr)); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/