On Mon 2016-08-29 00:35:40, 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. > > Note: > 1. Without this patch applied, it is possible that BIOS has > provided an inconsistent memory map, but the resume kernel is still > able to restore the image anyway(e.g., E820_RAM region is the subset > of the previous one), although the system might be unstable. So this > patch tries to treat any inconsistent e820 as illegal. > > 2. Another case is, this patch replies on comparing the e820_saved, but > currently the e820_save might not be strictly the same across > hibernation, even if BIOS has provided consistent e820 map - In > theory mptable might modify the BIOS-provided e820_saved dynamically > in early_reserve_e820_mpc_new, which would allocate a buffer from > E820_RAM, and marks it from E820_RAM to E820_RESERVED). > This is a potential and rare case we need to deal with in OS in > the future. > > Suggested-by: Pavel Machek <pa...@ucw.cz> > Suggested-by: Rafael J. Wysocki <rafael.j.wyso...@intel.com> > Cc: Lee, Chun-Yi <j...@suse.com> > Cc: Borislav Petkov <b...@alien8.de> > Signed-off-by: Chen Yu <yu.c.c...@intel.com>
Acked-by: Pavel Machek <pa...@ucw.cz> You might want to verify that panic is actually visible on affected platform. Thanks for your patience ;-). Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html