Re: unaligned accesses in SLAB etc.

From: David Miller
Date: Tue Oct 14 2014 - 17:32:53 EST


From: mroos@xxxxxxxx
Date: Wed, 15 Oct 2014 00:19:36 +0300 (EEST)

>> > I'd like to know that your another problem is related to commit
>> > bf0dea23a9c0 ("mm/slab: use percpu allocator for cpu cache"). So,
>> > if the commit is reverted, your another problem is also gone
>> > completely?
>>
>> The other problem has been present forever.
>
> Umm? I am afraid I have been describing it badly. This random
> SIGBUS+SIGSEGV problem is new - I have not seen it before.

Sorry, I thought it was the same bug that causes git corruptions
for you. I misunderstood.

> I have been able to do kernel compiles for years on sparc64 (modulo
> specific bugs in specific configurations) and 3.17 + start/end swap
> patch seems also stable for most machine. With yesterdays git + align
> patch, it dies with SIGBUS multiple times during compilation so it's a
> new regression for me.
>
> Will try reverting that commit tomorrow.

If that fails, please try to bisect, it will help us a lot.

> My only other current sparc64 problems that I am seeing - V210/V440 die
> during bootup if compiled with gcc 4.9 and V480 dies with FATAL
> exceptions during bootups since previous kernel release. Maybe also
> exit_mmap warning - I do not know if they have been fixed, I see them
> rarely.

The gcc-4.9 case is interesting, are you saying that a gcc-4.9 compiled
kernel works fine on other systems?
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