On Mon 2016-08-29 06:59:42, Borislav Petkov wrote: > On Mon, Aug 29, 2016 at 12:35:40AM +0800, Chen Yu wrote: > > On some platforms, there is occasional panic triggered when trying to > > resume from hibernation, a typical panic looks like: > > > > "BUG: unable to handle kernel paging request at ffff880085894000 > > IP: [<ffffffff810c5dc2>] load_image_lzo+0x8c2/0xe70" > > > > This is because e820 map has been changed by BIOS across > > hibernation, and one of the page frames from first kernel > > is right located in second kernel's unmapped region, so panic > > comes out when accessing unmapped kernel address. > > > > In order to expose this issue earlier, the md5 hash of e820 map > > is passed from suspend kernel to resume kernel, and the system will > > trigger panic once it finds the md5 value of previous kernel is not > > the same as current resume kernel. > > ... so basically now even the cases where it managed to resume would > panic because the digests differ, even if the original panic condition > doesn't trigger the bug, i.e. your Note 1 below.
Note where? You can't guarantee that e820 mismatch results in kernel panic, it could also be endless loop or data corruption. > The more important question IMHO would be, can we resume our system > successfully *even* if BIOS fiddled with the e820 map? Sounds about as easy as hot unplugging arbitrary memory address. IOW "not easy". Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html