panic in softdep_slowdown()
Neel Natu
neelnatu at gmail.com
Tue Feb 10 01:33:02 UTC 2015
A fix for this panic was submitted by kib@ as r277922:
https://svnweb.freebsd.org/base?view=revision&revision=277922
best
Neel
On Wed, Jan 28, 2015 at 11:54 AM, Neel Natu <neelnatu at gmail.com> wrote:
> Hi Gleb,
>
> On Wed, Jan 28, 2015 at 11:33 AM, Gleb Smirnoff <glebius at freebsd.org> wrote:
>> On Wed, Jan 28, 2015 at 09:04:42PM +0200, Konstantin Belousov wrote:
>> K> > I can't see where integer divide fault can happen with stat_flush_threads=1 :(
>> K>
>> K> Look at the exact asm instruction which faulted, also look at the registers
>> K> content.
>> K>
>> K> It might be hypervisor bug, after all.
>>
>> Yes, for me it looks like it. %edx should be one as well as -0x44(%rbp).
>>
>> 0xffffffff80895d43 <softdep_slowdown+435>: mov -0x20(%rbp),%ecx
>> 0xffffffff80895d46 <softdep_slowdown+438>: mov %ecx,%edx
>> 0xffffffff80895d48 <softdep_slowdown+440>: shr $0x1f,%edx
>> 0xffffffff80895d4b <softdep_slowdown+443>: add %edx,%ecx
>> 0xffffffff80895d4d <softdep_slowdown+445>: sar %ecx
>> 0xffffffff80895d4f <softdep_slowdown+447>: mov 0xffffffff80ee24c8,%edx
>> 0xffffffff80895d56 <softdep_slowdown+454>: mov %rax,-0x40(%rbp)
>> 0xffffffff80895d5a <softdep_slowdown+458>: mov %ecx,%eax
>> 0xffffffff80895d5c <softdep_slowdown+460>: mov %edx,-0x44(%rbp)
>> 0xffffffff80895d5f <softdep_slowdown+463>: cltd
>> 0xffffffff80895d60 <softdep_slowdown+464>: mov -0x44(%rbp),%ecx
>> 0xffffffff80895d63 <softdep_slowdown+467>: idiv %ecx
>>
>> (kgdb) p &stat_flush_threads
>> $5 = (int *) 0xffffffff80ee24c8
>> (kgdb) info registers
>> rax 0x12b86 76678
>> rbx 0x4 4
>> rcx 0x0 0
>> rdx 0x0 0
>> rsi 0x3e8 1000
>> rdi 0x99 153
>> rbp 0xfffffe001eb5f2b0 0xfffffe001eb5f2b0
>> ...
>> (kgdb) p *(int *)($rbp - 0x44)
>> $4 = 0
>> (kgdb) p *(int *)($rbp - 0x40)
>> $8 = 0
>> (kgdb) p &max_softdeps_hard
>> $11 = (int *) 0xfffffe001eb5f290
>> (kgdb) p (int *)($rbp - 0x20)
>> $12 = (int *) 0xfffffe001eb5f290
>> (kgdb) p max_softdeps_hard
>> $10 = 153357
>>
>
> Can you upload the core file and the kernel someplace that I can access?
>
> best
> Neel
>
>> --
>> Totus tuus, Glebius.
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