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Message-ID: <20100609140507.GA31154@redhat.com> Date: Wed, 9 Jun 2010 10:05:08 -0400 From: Vivek Goyal <vgoyal@...hat.com> To: Pavan Naregundi <pavan@...ux.vnet.ibm.com> Cc: Simon Horman <horms@...ge.net.au>, Américo Wang <xiyou.wangcong@...il.com>, linux-kernel@...r.kernel.org, hbabu@...ibm.com, kexec@...ts.infradead.org Subject: Re: [PATCH] Fix Oops in crash_shrink_memory On Wed, Jun 09, 2010 at 11:57:14AM +0530, Pavan Naregundi wrote: > On Wed, 2010-06-09 at 12:44 +0900, Simon Horman wrote: > > On Tue, Jun 08, 2010 at 03:11:47PM +0530, Pavan Naregundi wrote: > > > On Tue, 2010-06-08 at 16:54 +0800, Américo Wang wrote: > > > > On Tue, Jun 08, 2010 at 02:10:05PM +0530, Pavan Naregundi wrote: > > > > >On Tue, 2010-06-08 at 15:59 +0800, Américo 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@...il.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? > > > > > > Yes, it is a special case. > > > > > > Prepared a new patch which solves both of this issues. > > > > > > 1. OOPs in crash_shrink_memory > > > 2. make crash_get_memory_size to return correct size, in case of crash > > > memory not reserved. > > > > > > Patch is tested. > > > > > > > + if(crashk_res.end != crashk_res.start) > > > + size = crashk_res.end - crashk_res.start + 1; > > > > Minor style-issue: there should be a space between if and (. > > > > Sorry for that. > > Resending the patch with fixed style issues. > Looks good to me. Acked-by: Vivek Goyal <vgoyal@...hat.com> Thanks Vivek > Signed-off-by: Pavan Naregundi <pavan@...ux.vnet.ibm.com> > Reviewed-by: WANG Cong <xiyou.wangcong@...il.com> > -- > > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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