Hi, thanks for your interest :) On Tue, Aug 23, 2016 at 05:45:27PM +0800, joeyli wrote: > Hi all, > > On Wed, Oct 21, 2015 at 01:21:40PM +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 before/after > > 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 tell the user why this happeneded, and for scalability, > > we introduce a framework(a new file named hibernation_e820.c) to > > compare the e820 maps before/after hibernation. If these two > > e820 maps are not compatible with each other, we will print > > warning about the first corrupt e820 entry's information > > (there might be more than one broken e820 entries) once the > > system goes into panic, for example: > > > > BUG: unable to handle kernel paging request at ffff8800a9688000 > > IP: [<ffffffff810c5dc2>] load_image_lzo+0x8c2/0xe70 > > PM: Hibernation Caution! Oops might be due to inconsistent e820 table. > > PM: mem [0xa963b000-0xa963d000][ACPI Table] is an invalid old e820 region. > > PM: Inconsistent with current [mem 0xa963b000-0xa963e000][ACPI Table]. > > PM: Please update your BIOS, or do not use hibernation on this machine. > > > > The following kind of e820 entries will be regarded as invalid ones: > > 1.E820_RAM: old region is not a subset of any current region. > > 2.E820_ACPI: old region is not strictly the same as any current > > region(example above). > > > > Signed-off-by: Chen Yu <[email protected]> > > --- > > v6: > > - Fix some compiling errors reported by 0day/LKP, adjust > > Kconfig/variable namings. > > v5: > > - Rewrite this patch to just warn user of the broken BIOS > > when panic. > > v4: > > - Add __attribute__ ((unused)) for swsusp_page_is_valid, > > to eliminate the warnning of: > > 'swsusp_page_is_valid' defined but not used > > on non-x86 platforms. > > > > v3: > > - Adjust the logic to exclude the end_pfn boundary in pfn_mapped > > when invoking mark_valid_pages, because the end_pfn is not > > a mapped page frame, we should not regard it as a valid page. > > > > Move the sanity check of valid pages to a early stage in resuming > > process(moved to mark_unsafe_pages), in this way, we can avoid > > unnecessarily accessing these invalid pages in later stage(yes, > > move to the original position Joey once introduced in: > > Commit 84c91b7ae07c ("PM / hibernate: avoid unsafe pages in e820 > > reserved regions") > > > > With v3 patch applied, I did 30 cycles on my problematic platform, > > no panic triggered anymore(50% reproducible before patched, by > > plugging/unplugging memory peripheral during hibernation), and it > > just warns of invalid pages. > > > > v2: > > - According to Ingo's suggestion, rewrite this patch. > > > > New version just checks each page frame according to pfn_mapped array. > > So that we do not need to touch existing code related to > > E820_RESERVED_KERN. And this method can naturely guarantee > > that the system before/after hibernation do not need to be of > > the same memory size on x86_64. > > What's the progress of this patch? Looks already have experts review it. > Why this patch didn't accept? This patch is a little overkilled, and I have saved another simpler version to only check the md5 hash (as people suggested) for it. I can post it later.
thanks, Yu
