From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932370Ab3AITA0 (ORCPT ); Wed, 9 Jan 2013 14:00:26 -0500 Received: from e9.ny.us.ibm.com ([32.97.182.139]:45821 "EHLO e9.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932318Ab3AITAU (ORCPT ); Wed, 9 Jan 2013 14:00:20 -0500 Subject: [RFCv3][PATCH 3/3] make DEBUG_VIRTUAL work earlier in boot To: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, Gleb Natapov , Avi Kivity , Ingo Molnar , "H. Peter Anvin" , x86@kernel.org, Marcelo Tosatti , Dave Hansen From: Dave Hansen Date: Wed, 09 Jan 2013 13:59:06 -0500 References: <20130109185904.DD641DCE@kernel.stglabs.ibm.com> In-Reply-To: <20130109185904.DD641DCE@kernel.stglabs.ibm.com> Message-Id: <20130109185906.332FE569@kernel.stglabs.ibm.com> X-Content-Scanned: Fidelis XPS MAILER x-cbid: 13010919-7182-0000-0000-0000044DABAC Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The KVM code has some repeated bugs in it around use of __pa() on per-cpu data. Those data are not in an area on which __pa() is valid. However, they are also called early enough in boot that __vmalloc_start_set is not set, and thus the CONFIG_DEBUG_VIRTUAL debugging does not catch them. This adds a check to also verify them against max_low_pfn, which we can use earler in boot than is_vmalloc_addr(). However, if we are super-early in boot, max_low_pfn=0 and this will trip on every call, so also make sure that max_low_pfn is set. With this patch applied, CONFIG_DEBUG_VIRTUAL will actually catch the bug I was chasing. I'd love to find a generic way so that any __pa() call on percpu areas could do a BUG_ON(), but there don't appear to be any nice and easy ways to check if an address is a percpu one. Anybody have ideas on a way to do this? --- linux-2.6.git-dave/arch/x86/mm/numa.c | 2 +- linux-2.6.git-dave/arch/x86/mm/pat.c | 4 ++-- linux-2.6.git-dave/arch/x86/mm/physaddr.c | 9 ++++++++- 3 files changed, 11 insertions(+), 4 deletions(-) diff -puN arch/x86/mm/numa.c~make-DEBUG_VIRTUAL-work-earlier-in-boot arch/x86/mm/numa.c --- linux-2.6.git/arch/x86/mm/numa.c~make-DEBUG_VIRTUAL-work-earlier-in-boot 2013-01-09 13:55:44.718676439 -0500 +++ linux-2.6.git-dave/arch/x86/mm/numa.c 2013-01-09 13:55:44.726676509 -0500 @@ -219,7 +219,7 @@ static void __init setup_node_data(int n */ nd = alloc_remap(nid, nd_size); if (nd) { - nd_pa = __pa(nd); + nd_pa = __phys_addr_nodebug(nd); remapped = true; } else { nd_pa = memblock_alloc_nid(nd_size, SMP_CACHE_BYTES, nid); diff -puN arch/x86/mm/pat.c~make-DEBUG_VIRTUAL-work-earlier-in-boot arch/x86/mm/pat.c --- linux-2.6.git/arch/x86/mm/pat.c~make-DEBUG_VIRTUAL-work-earlier-in-boot 2013-01-09 13:55:44.722676474 -0500 +++ linux-2.6.git-dave/arch/x86/mm/pat.c 2013-01-09 13:55:44.726676509 -0500 @@ -560,10 +560,10 @@ int kernel_map_sync_memtype(u64 base, un { unsigned long id_sz; - if (base >= __pa(high_memory)) + if (base > __pa(high_memory-1)) return 0; - id_sz = (__pa(high_memory) < base + size) ? + id_sz = (__pa(high_memory-1) <= base + size) ? __pa(high_memory) - base : size; diff -puN arch/x86/mm/physaddr.c~make-DEBUG_VIRTUAL-work-earlier-in-boot arch/x86/mm/physaddr.c --- linux-2.6.git/arch/x86/mm/physaddr.c~make-DEBUG_VIRTUAL-work-earlier-in-boot 2013-01-09 13:55:44.722676474 -0500 +++ linux-2.6.git-dave/arch/x86/mm/physaddr.c 2013-01-09 13:55:44.726676509 -0500 @@ -1,3 +1,4 @@ +#include #include #include #include @@ -47,10 +48,16 @@ EXPORT_SYMBOL(__virt_addr_valid); #ifdef CONFIG_DEBUG_VIRTUAL unsigned long __phys_addr(unsigned long x) { + unsigned long phys_addr = x - PAGE_OFFSET; /* VMALLOC_* aren't constants */ VIRTUAL_BUG_ON(x < PAGE_OFFSET); VIRTUAL_BUG_ON(__vmalloc_start_set && is_vmalloc_addr((void *) x)); - return x - PAGE_OFFSET; + /* max_low_pfn is set early, but not _that_ early */ + if (max_low_pfn) { + VIRTUAL_BUG_ON((phys_addr >> PAGE_SHIFT) > max_low_pfn); + BUG_ON(slow_virt_to_phys((void *)x) != phys_addr); + } + return phys_addr; } EXPORT_SYMBOL(__phys_addr); #endif _