Messages in this thread | | | From | "Rafael J. Wysocki" <> | Subject | Re: Resume Issues :Exec of NX page, Synaptics Botchup | Date | Mon, 23 May 2011 23:22:37 +0200 |
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On Monday, May 23, 2011, Yu, Fenghua wrote: > > On Monday, May 23, 2011, Parag Warudkar wrote: > > > > > > On Sun, 22 May 2011, Linus Torvalds wrote: > > > > > > > > > > > Hmm. The "Code: " line is just full of complete garbage, so I think > > > > the real issue is that you really are trying to execute data. > > > > > > > > And that in turn seems to be because "setup_disablecpuid()" has > > > > actually been free'd, because it is marked as __init. > > > > > > > > Which is fine at the initial bootup, but not so fine at resume > > time, > > > > since it was free'd long long ago by then. > > > > > > > > And it definitely shouldn' t be called at resume time. There's > > > > something wrong there. That call trace is odd: > > > > > > > > Call Trace: > > > > [<ffffffff8148a119>] ? identify_cpu+0xd8/0x2d8 > > > > [<ffffffff8148a32d>] identify_secondary_cpu+0x14/0x1b > > > > [<ffffffff8148bf0f>] smp_store_cpu_info+0x3c/0x3e > > > > [<ffffffff8148c2ef>] start_secondary+0xf7/0x1d2 > > > > > > > > because none of those should be calling "setup_disablecpuid()" at > > all. > > > > > > > > Hmm. In fact, RIP is "setup_disablecpuid+0x40/0x40", ie it is one > > past > > > > the _end_ of setup_disablecpuid. > > > > > > > > I suspect that is actually "setup_smep()" that got called, an dthat > > > > there was some garbage data in there that caused it to jump back a > > > > bit. > > > > > > > > Does the attached patch fix it? > > > > > > > > > > Now I get a different call trace for the same NX error. (And > > Synaptics is > > > completely dead this time - not attributable to the patch, it was > > dumb > > > luck perhaps that it wored last time.) > > > > Any chance to try with commit de5397ad5b9ad22e2401c4dacdf1bb3b19c05679 > > (x86, cpu: Enable/disable Supervisor Mode Execution Protection) > > reverted? > > > > Rafael > > de5397ad5b9ad22e2401c4dacdf1bb3b19c05679 shouldn't affect a system unless the CPU has SMEP feature which is unlikely available out there. > > You can check if your CPU has "smep" feature in /proc/cpuinfo. Unlikely you will see the feature on your machine. Then the commit shouldn't cause the problem. > > You can unconditionally disable SMEP by kernel option "nosmep".
Still, it is known to cause problems to people (see for example https://bugzilla.kernel.org/show_bug.cgi?id=35602), so it might be a good idea to set "nosmep" by default.
Thanks, Rafael
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