Re: unaligned accesses in SLAB etc.

From: Meelis Roos
Date: Fri Oct 17 2014 - 07:12:16 EST


> From: David Miller <davem@xxxxxxxxxx>
> Date: Thu, 16 Oct 2014 16:20:01 -0400 (EDT)
>
> > So I'm going to audit all the code paths to make sure we don't put garbage
> > into the fault_code value.
>
> There are two code paths where we can put garbage into the fault_code
> value. And for the dtlb_prot.S case, the value we put in there is
> TLB_TAG_ACCESS which is 0x30, which include bit 0x20 which is that
> FAULT_CODE_BAD_RA indication which is erroneously triggering.
>
> The other path is via hugepage TLB misses, for the situation where
> we haven't allocated the huge TSB for the thread yet. That might
> explain some other longer-term problems we've had.
>
> I'm about to test the following fix:

Thank you - it seems to work fine for me on E3500 on top of
3.17.0-07551-g052db7e + slab alignment fix.

However, on top of mainline HEAD 3.17.0-09670-g0429fbc it explodes with
scheduler BUG - just reported to LKML + sched maintainers.

--
Meelis Roos (mroos@xxxxxxxx)
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