From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756410Ab0FGH2j (ORCPT ); Mon, 7 Jun 2010 03:28:39 -0400 Received: from e23smtp03.au.ibm.com ([202.81.31.145]:34963 "EHLO e23smtp03.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756302Ab0FGH2i (ORCPT ); Mon, 7 Jun 2010 03:28:38 -0400 Subject: [PATCH] Fix Oops in crash_shrink_memory From: Pavan Naregundi To: linux-kernel@vger.kernel.org Content-Type: multipart/mixed; boundary="=-WY5vL459Y65+zuxmBxma" Date: Mon, 07 Jun 2010 12:58:31 +0530 Message-ID: <1275895711.4365.18.camel@pavan.naregundi> Mime-Version: 1.0 X-Mailer: Evolution 2.28.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --=-WY5vL459Y65+zuxmBxma Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Hi Everyone, Please add me to CC in your reply.. When crashkernel is not enabled, "echo 0 > /sys/kernel/kexec_crash_size" will generate OOPS message in the kernel. Below is the OOPS message and other details, # cat /proc/cmdline ro LANG=en_US.UTF-8 SYSFONT=latarcyrheb-sun16 KEYTABLE=us console=hvc0 rhgb root=UUID=eafd9874-010c-46f9-a0c6-ea8db7c61ac3 # uname -a Linux XXXXXXXX 2.6.35-rc1 #1 SMP Mon Jun 7 18:04:53 IST 2010 ppc64 ppc64 ppc64 GNU/Linux # cd /sys/kernel/ # ls debug kexec_loaded profiling uevent_seqnum kexec_crash_loaded mm security vmcoreinfo kexec_crash_size notes uevent_helper # cat kexec_crash_loaded 0 # cat kexec_loaded 0 # cat kexec_crash_size 1 # echo 0 > kexec_crash_size Unable to handle kernel paging request for data at address 0x00000030 Faulting instruction address: 0xc0000000000930b4 Oops: Kernel access of bad area, sig: 11 [#1] SMP NR_CPUS=1024 NUMA pSeries last sysfs file: /sys/kernel/kexec_crash_size Modules linked in: sunrpc ipv6 ext3 jbd dm_mirror dm_region_hash dm_log dm_multipath dm_mod uinput sg ehea sr_mod ibmveth cdrom ext4 jbd2 mbcache sd_mod crc_t10dif ibmvscsic scsi_transport_srp scsi_tgt [last unloaded: scsi_wait_scan] NIP: c0000000000930b4 LR: c0000000000930ac CTR: c0000000000b7ce0 REGS: c0000000b7803750 TRAP: 0300 Not tainted (2.6.35-rc1) MSR: 8000000000009032 CR: 28242482 XER: 20000000 DAR: 0000000000000030, DSISR: 0000000040000000 TASK = c0000000b9cc3dc0[1381] 'bash' THREAD: c0000000b7800000 CPU: 12 GPR00: c0000000000930ac c0000000b78039d0 c000000000e885a8 c000000000f42950 GPR04: c0000000b7803af0 0000000000000008 0000000000000002 c0000000005c6438 GPR08: 0000000000000000 000000008000000c 0000000000000000 0000000000000000 GPR12: 0000000040242448 c000000007441e00 00000000100f6210 0000000000000000 GPR16: 00000000100f4a38 00000000100cfb98 00000000100f4bdc 00000000100f4b4c GPR20: 00000000103f4de8 0000000000000000 0000000000000000 00000000100f0000 GPR24: c0000000005c65c0 0000000000000000 c000000000da83e0 c0000000bc67f780 GPR28: c0000000bc684ae0 c000000000f42950 c000000000e1e3f8 c000000000da8408 NIP [c0000000000930b4] .release_resource+0x34/0xe0 LR [c0000000000930ac] .release_resource+0x2c/0xe0 Call Trace: [c0000000b78039d0] [c0000000000930ac] .release_resource+0x2c/0xe0 (unreliable) [c0000000b7803a60] [c0000000000d4fc8] .crash_shrink_memory+0x1c8/0x1f0 [c0000000b7803b30] [c0000000000b7d38] .kexec_crash_size_store+0x58/0x90 [c0000000b7803bc0] [c0000000002b0bb4] .kobj_attr_store+0x34/0x50 [c0000000b7803c30] [c000000000226d5c] .sysfs_write_file+0xec/0x1f0 [c0000000b7803ce0] [c00000000019e0bc] .vfs_write+0xec/0x1f0 [c0000000b7803d80] [c00000000019e2e8] .SyS_write+0x58/0xb0 [c0000000b7803e30] [c00000000000852c] syscall_exit+0x0/0x40 Instruction dump: fba1ffe8 fbc1fff0 fbe1fff8 ebc2b228 7c7f1b78 f8010010 f821ff71 ebbe8000 7fa3eb78 484e35d9 60000000 e97f0020 2fa90000 419e002c 7fbf4800 ---[ end trace afbc780462c9bf4e ]--- When crashkernel is not enabled, crashk_res resource have not been reserved. Hence crashk_res.parent will be NULL. Attaching a simple patch to this problem. Patch is tested and resolves this bug. Thanks.. Pavan --=-WY5vL459Y65+zuxmBxma Content-Disposition: attachment; filename="fix-crash_shrink_memory.patch" Content-Type: text/x-patch; name="fix-crash_shrink_memory.patch"; charset="UTF-8" Content-Transfer-Encoding: 7bit diff -Naur a/kernel/kexec.c b/kernel/kexec.c --- a/kernel/kexec.c 2010-06-07 18:45:55.050000000 +0530 +++ b/kernel/kexec.c 2010-06-07 18:50:28.070000004 +0530 @@ -1134,7 +1134,7 @@ free_reserved_phys_range(end, crashk_res.end); - if (start == end) + if ((start == end) && (crashk_res.parent != NULL)) release_resource(&crashk_res); crashk_res.end = end - 1; --=-WY5vL459Y65+zuxmBxma--