On Tuesday, July 26, 2016 04:53:19 PM Josh Poimboeuf wrote: > On Tue, Jul 26, 2016 at 10:15:39PM +0200, Rafael J. Wysocki wrote: > > On Tuesday, July 26, 2016 09:39:05 AM Josh Poimboeuf wrote: > > > On Tue, Jul 26, 2016 at 01:32:28PM +0200, Rafael J. Wysocki wrote: > > > > Hi, > > > > > > > > The following commit: > > > > > > > > commit 13523309495cdbd57a0d344c0d5d574987af007f > > > > Author: Josh Poimboeuf <jpoim...@redhat.com> > > > > Date: Thu Jan 21 16:49:21 2016 -0600 > > > > > > > > x86/asm/acpi: Create a stack frame in do_suspend_lowlevel() > > > > > > > > do_suspend_lowlevel() is a callable non-leaf function which doesn't > > > > honor CONFIG_FRAME_POINTER, which can result in bad stack traces. > > > > > > > > Create a stack frame for it when CONFIG_FRAME_POINTER is enabled. > > > > > > > > is reported to cause a resume-from-hibernation regression due to an > > > > attempt > > > > to execute an NX page (we've seen quite a bit of that recently). > > > > > > > > I'm asking the reporter to try 4.7, but if the problem is still there, > > > > we'll > > > > need to revert the above I'm afraid. > > > > So the bug is still there in 4.7 and it goes away after reverting the above > > commit. I guess I'll send a revert then. > > Hm, the code in wakeup_64.S seems quite magical, but I can't figure out > why this change causes a panic. Is it really causing the panic or is it > uncovering some other bug?
It doesn't matter really. It surely interacts with something in a really odd way, but that only means that its impact goes far beyond what was expected when it was applied. Its changelog is inadequate as a result and so on. > Maybe we should hold off on reverting until we understand the issue. Which very well may take forever. And AFAICS this is a fix for a theoretical issue and it *reliably* triggers a very practical kernel panic for this particular reporter. I'd rather live with the theoretical issue unfixed to be honest. Thanks, Rafael
