[BUGFIX PATCH][RESEND] kexec & iosapic: kexec oops when iosapic was removed

[BUGFIX PATCH][RESEND] kexec & iosapic: kexec oops when iosapic was removed

[Hanjun Guo]

Hi, all
We are working on a node hot-plug project, and IOAPIC is one of these devices to
be removed. but after IOSAPIC was removed, we use kexec to start a new kernel,
oops happended.

I reviewed the code and find out:
iosapic_remove
  iosapic_free
    memset(&iosapic_lists[index], 0, sizeof(iosapic_lists[0]))
      iosapic_lists[index].addr was set to 0;

and then kexec a new kernel
kexec_disable_iosapic
  iosapic_write(rte->iosapic,..)
    __iosapic_write(iosapic->addr, reg, val);
      addr was set to 0 when iosapic_remove, and oops happened

here is the oops information:

Starting new kernel
kexec[11336]: Oops 8804682956800 [1]
Modules linked in: raw(N) ipv6(N) acpi_cpufreq(N) binfmt_misc(N) fuse(N) nls_iso
8859_1(N) loop(N) ipmi_si(N) ipmi_devintf(N) ipmi_msghandler(N) mca_ereport(N) s
csi_ereport(N) nic_ereport(N) pcie_ereport(N) err_transport(N) nvlist(PN) dm_mod
(N) tpm_tis(N) tpm(N) ppdev(N) tpm_bios(N) serio_raw(N) i2c_i801(N) iTCO_wdt(N)
i2c_core(N) iTCO_vendor_support(N) sg(N) ioatdma(N) igb(N) mptctl(N) dca(N) parp
ort_pc(N) parport(N) container(N) button(N) usbhid(N) hid(N) uhci_hcd(N) ehci_hc
d(N) usbcore(N) sd_mod(N) crc_t10dif(N) ext3(N) mbcache(N) jbd(N) fan(N) process
or(N) ide_pci_generic(N) ide_core(N) ata_piix(N) libata(N) mptsas(N) mptscsih(N)
 mptbase(N) scsi_transport_sas(N) scsi_mod(N) thermal(N) thermal_sys(N) hwmon(N)

Supported: Yes, External

Pid: 11336, CPU 0, comm:                kexec
psr : 0000101009522030 ifs : 8000000000000791 ip  : [<a00000010004c160>]    Tain
ted: P          N  (2.6.32.12_RAS_V1R3C00B011)
ip is at kexec_disable_iosapic+0x120/0x1e0
unat: 0000000000000000 pfs : 0000000000000791 rsc : 0000000000000003
rnat: 0000000000000000 bsps: 0000000000000000 pr  : 65519aa6a555a659
ldrs: 0000000000000000 ccv : 00000000ea3cf51e fpsr: 0009804c8a70033f
csd : 0000000000000000 ssd : 0000000000000000
b0  : a00000010004c150 b6  : a000000100012620 b7  : a00000010000cda0
f6  : 000000000000000000000 f7  : 1003e0000000002000000
f8  : 1003e0000000050000003 f9  : 1003e0000028fb97183cd
f10 : 1003ee9f380df3c548b67 f11 : 1003e00000000000000cc
r1  : a0000001016cf660 r2  : 0000000000000000 r3  : 0000000000000000
r8  : 0000001009526030 r9  : a000000100012620 r10 : e00000010053f600
r11 : c0000000fec34040 r12 : e00000078f76fd30 r13 : e00000078f760000
r14 : 0000000000000000 r15 : 0000000000000000 r16 : 0000000000000000
r17 : 0000000000000000 r18 : 0000000000007fff r19 : 0000000000000000
r20 : 0000000000000000 r21 : e00000010053f590 r22 : a000000100cf0000
r23 : 0000000000000036 r24 : e0000007002f8a84 r25 : 0000000000000022
r26 : e0000007002f8a88 r27 : 0000000000000020 r28 : 0000000000000002
r29 : a0000001012c8c60 r30 : 0000000000000000 r31 : 0000000000322e49

Call Trace:
 [<a000000100018ca0>] show_stack+0x80/0xa0
                                spà0000078f76f8f0 bspà0000078f761380
 [<a000000100019300>] show_regs+0x640/0x920
                                spà0000078f76fac0 bspà0000078f761328
 [<a00000010002a130>] die+0x190/0x2e0
                                spà0000078f76fad0 bspà0000078f7612e8
 [<a000000100922fa0>] ia64_do_page_fault+0x840/0xb20
                                spà0000078f76fad0 bspà0000078f761288
 [<a00000010000d5c0>] ia64_native_leave_kernel+0x0/0x270
                                spà0000078f76fb60 bspà0000078f761288
 [<a00000010004c160>] kexec_disable_iosapic+0x120/0x1e0
                                spà0000078f76fd30 bspà0000078f761200
 [<a000000100016970>] machine_shutdown+0x110/0x140
                                spà0000078f76fd30 bspà0000078f7611c8
 [<a000000100133530>] kernel_kexec+0xd0/0x120
                                spà0000078f76fd30 bspà0000078f7611a0
 [<a0000001000eca40>] sys_reboot+0x480/0x4e0
                                spà0000078f76fd30 bspà0000078f761128
 [<a00000010000d420>] ia64_ret_from_syscall+0x0/0x20
                                spà0000078f76fe30 bspà0000078f761120
Kernel panic - not syncing: Fatal exception
irq 69: nobody cared (try booting with the "irqpoll" option)


Signed-off-by: Hanjun Guo <guohanjun@huawei.com>
Signed-off-by: Jianguo Wu <wujianguo@huawei.com>
---
 arch/ia64/kernel/iosapic.c |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)

diff --git a/arch/ia64/kernel/iosapic.c b/arch/ia64/kernel/iosapic.c
index ef4b5d8..11ce1ec 100644
--- a/arch/ia64/kernel/iosapic.c
+++ b/arch/ia64/kernel/iosapic.c
@@ -276,6 +276,9 @@ kexec_disable_iosapic(void)
 		vec = irq_to_vector(irq);
 		list_for_each_entry(rte, &info->rtes,
 				rte_list) {
+			if (rte->refcnt = NO_REF_RTE)
+				continue;
+
 			iosapic_write(rte->iosapic,
 					IOSAPIC_RTE_LOW(rte->rte_index),
 					IOSAPIC_MASK|vec);
-- 
1.7.6.1



.

RE: [BUGFIX PATCH][RESEND] kexec & iosapic: kexec oops when iosapic was removed

[Luck, Tony]

>		vec = irq_to_vector(irq);
> 		list_for_each_entry(rte, &info->rtes,
> 				rte_list) {
> +			if (rte->refcnt = NO_REF_RTE)
> +				continue;
> +
> 			iosapic_write(rte->iosapic,
> 					IOSAPIC_RTE_LOW(rte->rte_index),
> 					IOSAPIC_MASK|vec);

This will work - but is it papering over a problem when you removed the
iosapic? Should we really have removed this "rte" from rte_list when the
iosapic was removed?

-Tony

.

Re: [BUGFIX PATCH][RESEND] kexec & iosapic: kexec oops when iosapic was removed

[Hanjun Guo]

On 2012/8/13 10:54, Luck, Tony wrote:
>> 		vec = irq_to_vector(irq);
>> 		list_for_each_entry(rte, &info->rtes,
>> 				rte_list) {
>> +			if (rte->refcnt = NO_REF_RTE)
>> +				continue;
>> +
>> 			iosapic_write(rte->iosapic,
>> 					IOSAPIC_RTE_LOW(rte->rte_index),
>> 					IOSAPIC_MASK|vec);
> 
> This will work - but is it papering over a problem when you removed the
> iosapic? Should we really have removed this "rte" from rte_list when the
> iosapic was removed?
> 
> -Tony
> 

Hi Tony,
    Thanks for your comments, and sorry for the late reply.

We only set rte->refcnt to NO_REF_RTE if no device attach to this RTE when
unregister a GSI, and increase the rte->refcnt if the RTE is already existing
when register a GSI, so "rte" will not removed from rte_list when the
iosapic is removed.

Actually, the rte_list will keep static when remove/add a existing iosapic
after boot up.

Should we remove the RTE from the rte_list? if yes, we will have more
to do than this patch.

Thanks
Hanjun Guo

Re: [BUGFIX PATCH][RESEND] kexec & iosapic: kexec oops when iosapic was removed

[Toshi Kani]

On Thu, 2012-08-16 at 18:28 +0800, Hanjun Guo wrote:
> On 2012/8/13 10:54, Luck, Tony wrote:
> >> 		vec = irq_to_vector(irq);
> >> 		list_for_each_entry(rte, &info->rtes,
> >> 				rte_list) {
> >> +			if (rte->refcnt = NO_REF_RTE)
> >> +				continue;
> >> +
> >> 			iosapic_write(rte->iosapic,
> >> 					IOSAPIC_RTE_LOW(rte->rte_index),
> >> 					IOSAPIC_MASK|vec);
> > 
> > This will work - but is it papering over a problem when you removed the
> > iosapic? Should we really have removed this "rte" from rte_list when the
> > iosapic was removed?
> > 
> > -Tony
> > 
> 
> Hi Tony,
>     Thanks for your comments, and sorry for the late reply.
> 
> We only set rte->refcnt to NO_REF_RTE if no device attach to this RTE when
> unregister a GSI, and increase the rte->refcnt if the RTE is already existing
> when register a GSI, so "rte" will not removed from rte_list when the
> iosapic is removed.

Hi Hanjun,

I think updating rte->refcnt makes sense as long as rte->iosapic points
to a valid iosapic entry.  It looks odd to me that rte->iosapic is left
pointing an invalid iosapic entry after this iosapic is removed.  So, I
agree with Tony's concern.

Thanks,
-Toshi


> Actually, the rte_list will keep static when remove/add a existing iosapic
> after boot up.
> 
> Should we remove the RTE from the rte_list? if yes, we will have more
> to do than this patch.
> 
> Thanks
> Hanjun Guo
> 
> --
> 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/

Re: [BUGFIX PATCH][RESEND] kexec & iosapic: kexec oops when iosapic was removed

[Hanjun Guo]

On 2012/8/17 3:33, Toshi Kani wrote:
> On Thu, 2012-08-16 at 18:28 +0800, Hanjun Guo wrote:
>> On 2012/8/13 10:54, Luck, Tony wrote:
>>>> 		vec = irq_to_vector(irq);
>>>> 		list_for_each_entry(rte, &info->rtes,
>>>> 				rte_list) {
>>>> +			if (rte->refcnt = NO_REF_RTE)
>>>> +				continue;
>>>> +
>>>> 			iosapic_write(rte->iosapic,
>>>> 					IOSAPIC_RTE_LOW(rte->rte_index),
>>>> 					IOSAPIC_MASK|vec);
>>>
>>> This will work - but is it papering over a problem when you removed the
>>> iosapic? Should we really have removed this "rte" from rte_list when the
>>> iosapic was removed?
>>>
>>> -Tony
>>>
>>
>> Hi Tony,
>>     Thanks for your comments, and sorry for the late reply.
>>
>> We only set rte->refcnt to NO_REF_RTE if no device attach to this RTE when
>> unregister a GSI, and increase the rte->refcnt if the RTE is already existing
>> when register a GSI, so "rte" will not removed from rte_list when the
>> iosapic is removed.
> 
> Hi Hanjun,
> 
> I think updating rte->refcnt makes sense as long as rte->iosapic points
> to a valid iosapic entry.  It looks odd to me that rte->iosapic is left
> pointing an invalid iosapic entry after this iosapic is removed.  So, I
> agree with Tony's concern.

Hi Toshi,

I agree with you and Tony.
I will find a better solution and do some clean up, and then send another patch.

Thanks
Hanjun Guo