On Mon, Apr 07, 2014 at 09:57:00PM +0200, Toralf Förster wrote: > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA256 > > On 04/07/2014 08:59 PM, Frederic Weisbecker wrote: > > On Mon, Apr 07, 2014 at 08:16:24PM +0200, Toralf Förster wrote: > >> -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 > >> > >> On 04/07/2014 05:07 PM, Peter Zijlstra wrote: > >>> On Mon, Apr 07, 2014 at 05:03:37PM +0200, Peter Zijlstra > >>> wrote: > >>>> So what I suspect at this point is that because i386 and > >>>> x86_64 have a difference in current_thread_info() (i386 is > >>>> stack based), we end up setting the TIF_NEED_RESCHED bit on > >>>> the wrong stack. > >>>> > >>>> Now I have some vague memories of propagating the TIF flags > >>>> on stack switch, but I cannot remember what arch we did that > >>>> for. Let me stare at this a little more. > >>>> > >>>> Also, IFF this is the case, then the fingered patch above > >>>> (and your suggested 'fix') aren't the real curlpit/cure but > >>>> simply make it more/less likely to happen. > >>>> > >>>> Now, Steve had a patch somewhere that would make i386 use > >>>> per-cpu variables for current_thread_info() just like x86_64 > >>>> already does I think. Let me go find them too. > >>> > >>> Ohh, goodie, they're already in Linus' tree. Could you see if > >>> current git still suffers this problem? > >>> > >> v3.14-10353-g2b3a8fd works fine AFAICS (BTW the fix is stable > >> material, right ?) > > > > If we are reffering to 198d208df4371734ac4728f69cb585c284d20a15 > > (x86: Keep thread_info on thread stack in x86_32) it doesn't carry > > a stable tag. > > > > So to be clear, you are saying that v3.14 is fine but other > > release are buggy? Which ones are these? > > > No, 3.13.x and 3.14 have the issue, latest git is fine and 3.12.x >
Ah ok. Hmm, Peter seemed to have an idea on a fix to backport so I'll let him handle that :) Thanks. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
