On 09/30, Linus Torvalds wrote:
>On Thu, Sep 21, 2017 at 12:02 AM, NeilBrown <ne...@suse.com> wrote:
>>
>> I think it is crashing in
>> static inline bool ata_is_host_link(const struct ata_link *link)
>> {
>> return link == &link->ap->link || link == link->ap->slave_link;
>> }
>
>Yes. The code is
>
> 1a: 8b 3a mov (%edx),%edi
> 1c: 8d 8f 40 16 00 00 lea 0x1640(%edi),%ecx
> 22: 39 ca cmp %ecx,%edx
> 24: 74 49 je 0x6f
> 26: b9 01 00 00 00 mov $0x1,%ecx
> 2b:* 39 97 80 24 00 00 cmp %edx,0x2480(%edi) <-- trapping instruction
> 31: 74 3c je 0x6f
>
>and that first "je" is the test for "link == &link->ap->link" (which
>only takes the address relative to "link->ap" - thus the "lea"), and
>that cmp that oopses is indeed loading that actual slave_link value.
>
>So I agree. "link->ap" is NULL for some odd reason.
>
>Hmm. Absolutely nothing has changed in libata-core.c recently,
>certainly not that async_port_probe() thing.
>
>So I suspect either it's just a timing difference, or it's some
>unrelated memory corruption.
>
>Xiaolong, I see that you have SLUB_DEBUG and SLUB_DEBUG_ON enabled,
>but wonder if you can recreate this with DEBUG_PAGEALLOC and/or
>DEBUG_OBJECTS enabled too?
>
Sorry for the late, just come back from vacation.
I retested with with DEBUG_PAGEALLOC and DEBUG_OBJECTS enabled for both
commit 47e0fb461f and commit 011067b056, and both showed the ata_dev_next
crash issue, so commit 47e0fb461f should be irrelevant, sorry for the noise.
Thanks,
Xiaolong
>Tejun, any ideas? The original report is at
>
> https://lkml.org/lkml/2017/9/20/939
>
>in case you don't see it in your inbox from lkml.
>
> Linus
