[linux-yocto] [PATCH 1/1] xilinx-zyqn: Move disable_nonboot_cpus() in front of local_irq_disable()
qwang2
quanyang.wang at windriver.com
Mon Oct 21 05:13:43 PDT 2019
Hi Michal,
On 2019/10/21 下午6:45, Michal Simek wrote:
> On 21. 10. 19 10:45, Quanyang Wang wrote:
>> Hi Michal,
>>
>> On 10/21/19 4:16 PM, Michal Simek wrote:
>>> On 21. 10. 19 7:50, quanyang.wang at windriver.com wrote:
>>>> From: Quanyang Wang <quanyang.wang at windriver.com>
>>>>
>>>> When run kdump with enabling CONFIG_DEBUG_PREEMPT, there is a calltrace
>>>> as below:
>>>>
>>>> BUG: using smp_processor_id() in preemptible [00000000] code: sh/303
>>>> caller is machine_crash_shutdown+0x2c/0xe8
>>>> CPU: 0 PID: 303 Comm: sh Kdump: loaded Not tainted
>>>> 5.2.20-yocto-standard #1
>>>> Hardware name: Xilinx Zynq Platform
>>>> [<80112ff4>] (unwind_backtrace) from [<8010ca4c>] (show_stack+0x18/0x1c)
>>>> [<8010ca4c>] (show_stack) from [<809b000c>] (dump_stack+0x70/0x8c)
>>>> [<809b000c>] (dump_stack) from [<80549a14>]
>>>> (debug_smp_processor_id+0xd4/0x118)
>>>> [<80549a14>] (debug_smp_processor_id) from [<80111428>]
>>>> (machine_crash_shutdown+0x2c/0xe8)
>>>> [<80111428>] (machine_crash_shutdown) from [<801afe24>]
>>>> (__crash_kexec+0x70/0xd0)
>>>> [<801afe24>] (__crash_kexec) from [<801259b4>] (panic+0x110/0x324)
>>>> [<801259b4>] (panic) from [<805f7018>] (sysrq_handle_crash+0x18/0x1c)
>>>> [<805f7018>] (sysrq_handle_crash) from [<805f7584>]
>>>> (__handle_sysrq+0x9c/0x14c)
>>>> [<805f7584>] (__handle_sysrq) from [<805f79e8>]
>>>> (write_sysrq_trigger+0x5c/0x6c)
>>>> [<805f79e8>] (write_sysrq_trigger) from [<8031e850>]
>>>> (proc_reg_write+0x78/0x8c)
>>>> [<8031e850>] (proc_reg_write) from [<802b1b28>] (vfs_write+0xc0/0x154)
>>>> [<802b1b28>] (vfs_write) from [<802b2a64>] (ksys_write+0x6c/0xd4)
>>>> [<802b2a64>] (ksys_write) from [<80101000>] (ret_fast_syscall+0x0/0x54)
>>>> Exception stack(0xba157fa8 to 0xba157ff0)
>>>> 7fa0: 00000002 005ab930 00000001 005ab930 00000002 00000000
>>>> 7fc0: 00000002 005ab930 76fa2290 00000004 76f3d124 76f3cc8c 00000000
>>>> 00000000
>>>> 7fe0: 00000004 7edec940 76edbfff 76e67d16
>>>>
>>>> This is because that the function disable_nonboot_cpus is called in
>>>> order to make sure that the crash kernel runs in the boot CPU(cpu0).
>>>> And it will enable local irq by calling as below:
>>>>
>>>> disable_nonboot_cpus
>>>> -> freeze_secondary_cpus
>>>> -> _cpu_down
>>>> -> percpu_down_write
>>>> -> rcu_sync_enter
>>>> -> spin_unlock_irq(&rsp->rss_lock)
>>>> -> local_irq_enable()
>>>>
>>>> Then the functions including smp_processor_id() behind
>>>> disable_nonboot_cpus
>>>> will run at the irq-enabled context, and this will trigger the
>>>> calltrace.
>>>>
>>>> So move disable_nonboot_cpus() in front of local_irq_disable() to avoid
>>>> it since disable_nonboot_cpus() not need run at an atomic context.
>>>>
>>>> Signed-off-by: Quanyang Wang <quanyang.wang at windriver.com>
>>>> ---
>>>> arch/arm/kernel/machine_kexec.c | 3 ++-
>>>> 1 file changed, 2 insertions(+), 1 deletion(-)
>>>>
>>>> diff --git a/arch/arm/kernel/machine_kexec.c
>>>> b/arch/arm/kernel/machine_kexec.c
>>>> index 654f2b1f9ac0..83d2025a4ab1 100644
>>>> --- a/arch/arm/kernel/machine_kexec.c
>>>> +++ b/arch/arm/kernel/machine_kexec.c
>>>> @@ -145,9 +145,10 @@ static void machine_kexec_mask_interrupts(void)
>>>> void machine_crash_shutdown(struct pt_regs *regs)
>>>> {
>>>> - local_irq_disable();
>>>> disable_nonboot_cpus();
>>>> + local_irq_disable();
>>>> +
>>>> crash_smp_send_stop();
>>>> crash_save_cpu(regs, smp_processor_id());
>>>>
>>> ok. Can you please check before this if your usecases work without
>>> disable_nonboot_cpus(). This patch was done pretty long time ago where
>>> there was an issue with kexec. Long time ago I was talking to arm-soc
>>> maintainers about this and they told me that mainline code should work
>>> fine without any need to call disable_nonboot_cpus().
>>> It means if kexec is working fine we can revert origin patch and use
>>> what mainline is using.
>> It seems that the issue is still there. When crash at cpu1 and crash
>> kernel runs at cpu1,
>>
>> it will hang, the log is as below:
>>
>> root at xilinx-zynq:~# sh 1.sh
>> syscall kexec_file_load not available.
>> sysrq: Trigger a crash
>> Kernel panic - not syncing: sysrq triggered crash
>> CPU: 1 PID: 308 Comm: sh Kdump: loaded Not tainted 5.2.20-yocto-standard #4
>> Hardware name: Xilinx Zynq Platform
>> [<80112eb0>] (unwind_backtrace) from [<8010cc04>] (show_stack+0x18/0x1c)
>> [<8010cc04>] (show_stack) from [<8094f8f4>] (dump_stack+0x70/0x8c)
>> [<8094f8f4>] (dump_stack) from [<801256f4>] (panic+0xf8/0x320)
>> [<801256f4>] (panic) from [<805dbeb0>] (sysrq_handle_crash+0x18/0x1c)
>> [<805dbeb0>] (sysrq_handle_crash) from [<805dc3b8>]
>> (__handle_sysrq+0x9c/0x148)
>> [<805dc3b8>] (__handle_sysrq) from [<805dc804>]
>> (write_sysrq_trigger+0x5c/0x6c)
>> [<805dc804>] (write_sysrq_trigger) from [<8031b040>]
>> (proc_reg_write+0x78/0x8c)
>> [<8031b040>] (proc_reg_write) from [<802aeec4>] (vfs_write+0xc0/0x154)
>> [<802aeec4>] (vfs_write) from [<802afd18>] (ksys_write+0x64/0xc8)
>> [<802afd18>] (ksys_write) from [<80101000>] (ret_fast_syscall+0x0/0x54)
>> Exception stack(0xb905bfa8 to 0xb905bff0)
>> bfa0: 00000002 0059afa0 00000001 0059afa0 00000002
>> 00000000
>> bfc0: 00000002 0059afa0 76f8e290 00000004 76f29124 76f28c8c 00000000
>> 00000000
>> bfe0: 00000004 7eb858c0 76ec7fff 76e53d16
>> CPU 0 will stop doing anything useful since another CPU has crashed
>> Loading crashdump kernel...
>> Bye!
>> Booting Linux on physical CPU 0x1
>> Linux version 5.2.20-yocto-standard (oe-user at oe-host) (gcc version 9.2.0
>> (GCC)) #1 SMP PREEMPT Thu Oct 17 08:15:14 UTC 2019
>> CPU: ARMv7 Processor [413fc090] revision 0 (ARMv7), cr=18c5387d
>> CPU: PIPT / VIPT nonaliasing data cache, VIPT aliasing instruction cache
>> OF: fdt: Machine model: Xilinx ZC706 board
>> OF: fdt: Ignoring memory range 0x0 - 0x8000000
>> printk: debug: ignoring loglevel setting.
>> printk: bootconsole [earlycon0] enabled
>> Memory policy: Data cache writealloc
>> cma: Reserved 16 MiB at 0x16c00000
>> On node 0 totalpages: 65280
>> Normal zone: 574 pages used for memmap
>> Normal zone: 0 pages reserved
>> Normal zone: 65280 pages, LIFO batch:15
>> percpu: Embedded 19 pages/cpu s47756 r8192 d21876 u77824
>> pcpu-alloc: s47756 r8192 d21876 u77824 alloc=19*4096
>> pcpu-alloc: [0] 0 [0] 1
>> Built 1 zonelists, mobility grouping on. Total pages: 64706
>> Kernel command line: console=ttyPS0,115200n8 root=/dev/nfs rw
>> nfsroot=128.224.165.20:/export/pxeboot/vlm-boards/22009/rootfs,v3,tcp
>> ip=128.224.179.217:128.224.165.20:128.224.178.1:255.255.254.0:zc702:eth0:off
>> ignore_loglevel earlyprintk noinitrd selinux=0 enforcing=0 kmemleak=on
>> elfcorehdr=0x17f00000 mem=261120K
>> Dentry cache hash table entries: 32768 (order: 5, 131072 bytes)
>> Inode-cache hash table entries: 16384 (order: 4, 65536 bytes)
>> Memory: 227332K/261120K available (9216K kernel code, 725K rwdata, 2284K
>> rodata, 1024K init, 567K bss, 17404K reserved, 16384K cma-reserved)
>> SLUB: HWalign=64, Order=0-3, MinObjects=0, CPUs=2, Nodes=1
>> ftrace: allocating 35203 entries in 69 pages
>> rcu: Preemptible hierarchical RCU implementation.
>> rcu: RCU restricting CPUs from NR_CPUS=4 to nr_cpu_ids=2.
>> Tasks RCU enabled.
>> rcu: RCU calculated value of scheduler-enlistment delay is 10 jiffies.
>> rcu: Adjusting geometry for rcu_fanout_leaf=16, nr_cpu_ids=2
>> NR_IRQS: 16, nr_irqs: 16, preallocated irqs: 16
>> efuse mapped to (ptrval)
>> slcr mapped to (ptrval)
>> L2C: platform provided aux values match the hardware, so have no
>> effect. Please remove them.
>> L2C-310 erratum 769419 enabled
>> L2C-310 enabling early BRESP for Cortex-A9
>> L2C-310: enabling full line of zeros but not enabled in Cortex-A9
>> L2C-310 ID prefetch enabled, offset 1 lines
>> L2C-310 dynamic clock gating enabled, standby mode enabled
>> L2C-310 cache controller enabled, 8 ways, 512 kB
>> L2C-310: CACHE_ID 0x410000c8, AUX_CTRL 0x76760001
>> random: get_random_bytes called from start_kernel+0x2b0/0x4c4 with
>> crng_init=0
>> zynq_clock_init: clkc starts at (ptrval)
>> Zynq clock init
>> sched_clock: 64 bits at 333MHz, resolution 3ns, wraps every 4398046511103ns
>> clocksource: arm_global_timer: mask: 0xffffffffffffffff max_cycles:
>> 0x4ce07af025, max_idle_ns: 440795209040 ns
>> Switching to timer-based delay loop, resolution 3ns
>> clocksource: ttc_clocksource: mask: 0xffff max_cycles: 0xffff,
>> max_idle_ns: 537538477 ns
>> timer #0 at (ptrval), irq=17
>> Console: colour dummy device 80x30
>> Calibrating delay loop (skipped), value calculated using timer
>> frequency.. 666.66 BogoMIPS (lpj=3333333)
>> pid_max: default: 32768 minimum: 301
>> LSM: Security Framework initializing
>> Mount-cache hash table entries: 1024 (order: 0, 4096 bytes)
>> Mountpoint-cache hash table entries: 1024 (order: 0, 4096 bytes)
>> CPU: Testing write buffer coherency: ok
>> CPU0: Spectre v2: using BPIALL workaround
>> CPU0: thread -1, cpu 1, socket 0, mpidr 80000001
>> Setting up static identity map for 0x8100000 - 0x8100060
>> rcu: Hierarchical SRCU implementation.
>> smp: Bringing up secondary CPUs ...
> ok. Can you send content of your 1.sh script?
The 1.sh and kdump_args is as below:
root at xilinx-zynq:~# cat 1.sh
#!/bin/sh
kexec -p /boot/zImage --append="$(<kdump_args)"
echo c > /proc/sysrq-trigger
root at xilinx-zynq:~# cat kdump_args
console=ttyPS0,115200n8 root=/dev/nfs rw
nfsroot=128.224.165.20:/export/pxeboot/vlm-boards/22009/rootfs,v3,tcp
ip=128.224.179.217:128.224.165.20:128.224.178.1:255.255.254.0:zc702:eth0:off
ignore_loglevel earlyprintk noinitrd selinux=0 enforcing=0 kmemleak=on
root at xilinx-zynq:~#
>
> Anyway the patch looks good to me.
> Bruce: Feel free to take it. I will add it to Xilinx tree too.
>
> Thanks,
> Michal
>
>
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