Messages in this thread | | | Date | Wed, 02 May 2012 23:40:04 -0700 | From | "H. Peter Anvin" <> | Subject | Re: Oops with DCACHE_WORD_ACCESS and ocfs2, autofs4 |
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On 05/02/2012 11:38 PM, H. Peter Anvin wrote: > On 05/02/2012 10:57 PM, Linus Torvalds wrote: >> >> There are multiple ways to fix this, including just marking that >> unaligned word access as being able to take an exception, but I had >> hoped to avoid having to do that. There are alternatives, like always >> padding allocations up by 7 bytes, but those are nasty too. So I'd >> like to understand what triggers this for Jana, it's possible we can >> just work around that particular issue. >> > > Can we do the trick of aligning the pointer and ignoring the start? > That would allow even architectures that don't have unaligned accesses > to work, too. > >> Apr 30 14:02:46 web5 kernel: RIP: e030:[<ffffffff8113c29b>] > [<ffffffff8113c29b>] link_path_walk+0xab/0x890 >> Apr 30 14:02:46 web5 kernel: RSP: e02b:ffff88001e7a3bc8 EFLAGS: 00010257 >> Apr 30 14:02:46 web5 kernel: CS: e033 > > These segment values look odd in the extreme... > >> Apr 30 14:02:46 web5 kernel: [<ffffffff810056c9>] ? > __raw_callee_save_xen_pmd_val+0x11/0x1e > > ... because he's running under Xen-PV. So his memory map can be > arbitrarily screwed seven ways to Sunday. >
This almost makes me want to suggest adding a taint flag for PV.
-hpa
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