On Tue, Jun 08, 2010 at 02:10:05PM +0530, Pavan Naregundi wrote: >On Tue, 2010-06-08 at 15:59 +0800, Am?rico Wang wrote: >> On Tue, Jun 08, 2010 at 12:37:37PM +0530, Pavan Naregundi wrote: >> >Adding CC's.. >> > >> > >> >On Mon, 2010-06-07 at 12:58 +0530, Pavan Naregundi wrote: >> >> 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 <EE,ME,IR,DR> 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 <e92b0030> 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. >> >> >> Ouch... >> >> The patch indeed addresses the problem, looks good to me. >> Please add your Signed-off-by and my: >> >> Reviewed-by: WANG Cong <xiyou.wangcong at gmail.com> >> >> Another problem is that you should get 0 instead of 1 when you don't >> reserve any memory. > >We get 1 here because, crash_get_memory_size() adds 1 as below, > >size = crashk_res.end - crashk_res.start + 1; > >We cant remove this addition, as it is required to display correct size >in case if we reserve the crash memory. Yeah, but 0 is a special case, isn't it? > >Coming back to issue.. Attaching the patch again. > >Signed-off-by: Pavan Naregundi <pavan at linux.vnet.ibm.com> >Reviewed-by: WANG Cong <xiyou.wangcong at gmail.com> Thanks! >--- >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; >
