Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756709Ab0FQQTK (ORCPT ); Thu, 17 Jun 2010 12:19:10 -0400 Received: from relay1.sgi.com ([192.48.179.29]:52279 "EHLO relay.sgi.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1760293Ab0FQQTI (ORCPT ); Thu, 17 Jun 2010 12:19:08 -0400 To: linux-kernel@vger.kernel.org Subject: per_cpu_ptr_to_phys() failure on UV x86_64 Cc: tj@kernel.org Message-Id: From: Cliff Wickman Date: Thu, 17 Jun 2010 11:20:26 -0500 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3344 Lines: 90 kdump is failing on an SGI UV system because it depends on /sys/devices/system/cpu/cpuN/crash_notes. And these files contain bad addresses for cpus beyond cpu 0. This occurs using 2.6.35-rc3 code. But the same problem looks present in 2.6.33. The problem traces to per_cpu_ptr_to_phys() -> pcpu_addr_to_page() -> vmalloc_to_page() for per-cpu addresses not in the first per-cpu 'chunk', but not in the VMALLOC_START/VMALLOC_END range. I wonder why this shows up on UV but not other x86_64's? I've included a patch that solves this for me. But I defer to the authors for a proper solution. This is where per_cpu_ptr_to_phys() is called for this /sys file: static ssize_t show_crash_notes(struct sys_device *dev, struct ... ... addr = per_cpu_ptr_to_phys(per_cpu_ptr(crash_notes, cpunum)); rc = sprintf(buf, "%Lx\n", addr); return rc; } The problem, without the below patch: (but a couple of printk's) uv3-sys:/tmp/cpw # cat /sys/devices/system/cpu/cpu0/crash_notes 1c1b040 uv3-sys:/tmp/cpw # cat /sys/devices/system/cpu/cpu1/crash_notes db74000000000000 uv3-sys:/tmp/cpw # cat /sys/devices/system/cpu/cpu2/crash_notes db74000000000000 uv3-sys:/tmp/cpw # dmesg | tail -n 6 [ 133.883009] cpw: per_cpu_ptr_to_phys addr ffff880001c1b040 [ 133.883012] cpw: per_cpu_ptr_to_phys returning 0x1c1b040 [ 136.910178] cpw: per_cpu_ptr_to_phys addr ffff880001c3b040 [ 136.910181] cpw: per_cpu_ptr_to_phys returning 0xdb74000000000000 [ 140.304825] cpw: per_cpu_ptr_to_phys addr ffff880001c5b040 [ 140.304828] cpw: per_cpu_ptr_to_phys returning 0xdb74000000000000 With the below patch: (plus a couple of printk's) uv3-sys: # cat /sys/devices/system/cpu/cpu0/crash_notes 1c1b040 uv3-sys: # cat /sys/devices/system/cpu/cpu1/crash_notes 1c3b040 uv3-sys: # cat /sys/devices/system/cpu/cpu2/crash_notes 1c5b040 uv3-sys: # dmesg | tail -n 6 [ 130.411358] cpw: per_cpu_ptr_to_phys addr ffff880001c1b040 [ 130.411361] cpw: per_cpu_ptr_to_phys returning 0x1c1b040 [ 135.420702] cpw: per_cpu_ptr_to_phys addr ffff880001c3b040 [ 135.420705] cpw: per_cpu_ptr_to_phys returning 0x1c3b040 [ 139.514014] cpw: per_cpu_ptr_to_phys addr ffff880001c5b040 [ 139.514016] cpw: per_cpu_ptr_to_phys returning 0x1c5b040 Diffed against 2.6.35-rc5 Signed-off-by: Cliff Wickman --- mm/percpu.c | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-) Index: linux-2.6.35-rc3/mm/percpu.c =================================================================== --- linux-2.6.35-rc3.orig/mm/percpu.c +++ linux-2.6.35-rc3/mm/percpu.c @@ -978,12 +978,11 @@ bool is_kernel_percpu_address(unsigned l */ phys_addr_t per_cpu_ptr_to_phys(void *addr) { + if ((unsigned long)addr < VMALLOC_START || + (unsigned long)addr >= VMALLOC_END) + return __pa(addr); if (pcpu_addr_in_first_chunk(addr)) { - if ((unsigned long)addr < VMALLOC_START || - (unsigned long)addr >= VMALLOC_END) - return __pa(addr); - else - return page_to_phys(vmalloc_to_page(addr)); + return page_to_phys(vmalloc_to_page(addr)); } else return page_to_phys(pcpu_addr_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/