On Wed, Mar 17, 2021 at 11:19 PM Josef Bacik <jo...@toxicpanda.com> wrote:
>
> On 3/16/21 10:50 PM, Kai-Heng Feng wrote:
> > Hi,
> >
> > On Wed, Mar 17, 2021 at 10:17 AM Josef Bacik <jo...@toxicpanda.com> wrote:
> >>
> >> This reverts commit d60cd06331a3566d3305b3c7b566e79edf4e2095.
> >>
> >> This patch causes a panic when rebooting my Dell Poweredge r440. I do
> >> not have the full panic log as it's lost at that stage of the reboot and
> >> I do not have a serial console. Reverting this patch makes my system
> >> able to reboot again.
> >
> > But this patch also helps many HP laptops, so maybe we should figure
> > out what's going on on Poweredge r440.
> > Does it also panic on shutdown?
> >
>
> Sure I'll test whatever to get it fixed, but I just wasted 3 days bisecting
> and
> lost a weekend of performance testing on btrfs because of this regression, so
> until you figure out how it broke it needs to be reverted so people don't have
> to figure out why reboot suddenly isn't working.
That's unfortunate to hear. However, I've been spending tons of time
on bisecting kernels. To me it's just a normal part of kernel
development so I won't call it "wasted".
Feel free to revert the patch though.
>
> Running "halt" has the same effect with and without your patch, it gets to
> "system halted" and just sits there without powering off. Not entirely sure
> why
> that is, but there's no panic.
What about shutdown? pm_power_off_prepare() is used by shutdown but
it's not used by halt.
Kai-Heng
>
> The panic itself is lost, but I see there's an NMI and I have the RIP
>
> (gdb) list *('mwait_idle_with_hints.constprop.0'+0x4b)
> 0xffffffff816dabdb is in mwait_idle_with_hints
> (./arch/x86/include/asm/current.h:15).
> 10
> 11 DECLARE_PER_CPU(struct task_struct *, current_task);
> 12
> 13 static __always_inline struct task_struct *get_current(void)
> 14 {
> 15 return this_cpu_read_stable(current_task);
> 16 }
> 17
> 18 #define current get_current()
> 19
>
> <mwait_idle_with_hints.constprop.0>: jmp 0xffffffff936dac02
> <mwait_idle_with_hints.constprop.0+0x72>
> <mwait_idle_with_hints.constprop.0+0x2>: nopl (%rax)
> <mwait_idle_with_hints.constprop.0+0x5>: jmp 0xffffffff936dabac
> <mwait_idle_with_hints.constprop.0+0x1c>
> <mwait_idle_with_hints.constprop.0+0x7>: nopl (%rax)
> <mwait_idle_with_hints.constprop.0+0xa>: mfence
> <mwait_idle_with_hints.constprop.0+0xd>: mov %gs:0x17bc0,%rax
> <mwait_idle_with_hints.constprop.0+0x16>: clflush (%rax)
> <mwait_idle_with_hints.constprop.0+0x19>: mfence
> <mwait_idle_with_hints.constprop.0+0x1c>: xor %edx,%edx
> <mwait_idle_with_hints.constprop.0+0x1e>: mov %rdx,%rcx
> <mwait_idle_with_hints.constprop.0+0x21>: mov %gs:0x17bc0,%rax
> <mwait_idle_with_hints.constprop.0+0x2a>: monitor %rax,%rcx,%rdx
> <mwait_idle_with_hints.constprop.0+0x2d>: mov (%rax),%rax
> <mwait_idle_with_hints.constprop.0+0x30>: test $0x8,%al
> <mwait_idle_with_hints.constprop.0+0x32>: jne 0xffffffff936dabdb
> <mwait_idle_with_hints.constprop.0+0x4b>
> <mwait_idle_with_hints.constprop.0+0x34>: jmpq 0xffffffff936dabd0
> <mwait_idle_with_hints.constprop.0+0x40>
> <mwait_idle_with_hints.constprop.0+0x39>: verw 0x9f9fec(%rip) #
> 0xffffffff940d4bbc
> <mwait_idle_with_hints.constprop.0+0x40>: mov $0x1,%ecx
> <mwait_idle_with_hints.constprop.0+0x45>: mov %rdi,%rax
> <mwait_idle_with_hints.constprop.0+0x48>: mwait %rax,%rcx
> <mwait_idle_with_hints.constprop.0+0x4b>: mov %gs:0x17bc0,%rax
> <mwait_idle_with_hints.constprop.0+0x54>: lock andb $0xdf,0x2(%rax)
> <mwait_idle_with_hints.constprop.0+0x59>: lock addl $0x0,-0x4(%rsp)
> <mwait_idle_with_hints.constprop.0+0x5f>: mov (%rax),%rax
> <mwait_idle_with_hints.constprop.0+0x62>: test $0x8,%al
> <mwait_idle_with_hints.constprop.0+0x64>: je 0xffffffff936dac01
> <mwait_idle_with_hints.constprop.0+0x71>
> <mwait_idle_with_hints.constprop.0+0x66>: andl
> $0x7fffffff,%gs:0x6c93cf7f(%rip) # 0x17b80
> <mwait_idle_with_hints.constprop.0+0x71>: retq
> <mwait_idle_with_hints.constprop.0+0x72>: mov %gs:0x17bc0,%rax
> <mwait_idle_with_hints.constprop.0+0x7b>: lock orb $0x20,0x2(%rax)
> <mwait_idle_with_hints.constprop.0+0x80>: mov (%rax),%rax
> <mwait_idle_with_hints.constprop.0+0x83>: test $0x8,%al
> <mwait_idle_with_hints.constprop.0+0x85>: jne 0xffffffff936dabdb
> <mwait_idle_with_hints.constprop.0+0x4b>
> <mwait_idle_with_hints.constprop.0+0x87>: jmpq 0xffffffff936dab95
> <mwait_idle_with_hints.constprop.0+0x5>
> <mwait_idle_with_hints.constprop.0+0x8c>: nopl 0x0(%rax)
>
> 0x4b is after the mwait, which means we're panicing in the
> current_clr_polling(), where we do clear_thread_flag(TIF_POLLING_NRFLAG).
> Thanks,
>
> Josef
