From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx130.postini.com [74.125.245.130]) by kanga.kvack.org (Postfix) with SMTP id 4BDB56B0075 for ; Fri, 7 Dec 2012 16:30:37 -0500 (EST) Received: from /spool/local by e8.ny.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Fri, 7 Dec 2012 16:30:35 -0500 Received: from d01relay04.pok.ibm.com (d01relay04.pok.ibm.com [9.56.227.236]) by d01dlp02.pok.ibm.com (Postfix) with ESMTP id ACF576E8047 for ; Fri, 7 Dec 2012 16:30:32 -0500 (EST) Received: from d03av03.boulder.ibm.com (d03av03.boulder.ibm.com [9.17.195.169]) by d01relay04.pok.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id qB7LUVMo254410 for ; Fri, 7 Dec 2012 16:30:31 -0500 Received: from d03av03.boulder.ibm.com (loopback [127.0.0.1]) by d03av03.boulder.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id qB7LURQI003934 for ; Fri, 7 Dec 2012 14:30:27 -0700 Subject: [RFCv2][PATCH 3/3] make DEBUG_VIRTUAL work earlier in boot From: Dave Hansen Date: Fri, 07 Dec 2012 16:30:25 -0500 References: <20121207213023.AA3AFF11@kernel.stglabs.ibm.com> In-Reply-To: <20121207213023.AA3AFF11@kernel.stglabs.ibm.com> Message-Id: <20121207213025.53E4BD1B@kernel.stglabs.ibm.com> Sender: owner-linux-mm@kvack.org List-ID: To: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, Gleb Natapov , Avi Kivity , Dave Hansen 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 | 10 ++++++++-- 3 files changed, 11 insertions(+), 5 deletions(-) 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 2012-11-30 16:18:44.522847232 -0500 +++ linux-2.6.git-dave/arch/x86/mm/physaddr.c 2012-11-30 16:18:44.530847298 -0500 @@ -1,3 +1,4 @@ +#include #include #include #include @@ -41,16 +42,21 @@ bool __virt_addr_valid(unsigned long x) return pfn_valid(x >> PAGE_SHIFT); } EXPORT_SYMBOL(__virt_addr_valid); - #else #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 diff -puN arch/x86/kernel/kvmclock.c~make-DEBUG_VIRTUAL-work-earlier-in-boot arch/x86/kernel/kvmclock.c diff -L sr -puN /dev/null /dev/null diff -puN arch/x86/include/asm/page_32.h~make-DEBUG_VIRTUAL-work-earlier-in-boot arch/x86/include/asm/page_32.h 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 2012-11-30 16:18:44.526847265 -0500 +++ linux-2.6.git-dave/arch/x86/mm/numa.c 2012-11-30 16:18:44.534847331 -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 2012-11-30 16:19:34.371258739 -0500 +++ linux-2.6.git-dave/arch/x86/mm/pat.c 2012-11-30 16:22:38.528778740 -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; _ -- 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