On Mon, Oct 21, 2019 at 6:45 AM Michal Simek <michal.si...@xilinx.com> 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.w...@windriver.com wrote:
> >>> From: Quanyang Wang <quanyang.w...@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.w...@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@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@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?
>
> Anyway the patch looks good to me.
> Bruce: Feel free to take it. I will add it to Xilinx tree too.
Ack'd. Will pull it into my queue.
Bruce
>
> Thanks,
> Michal
>
>
--
- Thou shalt not follow the NULL pointer, for chaos and madness await
thee at its end
- "Use the force Harry" - Gandalf, Star Trek II
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