Messages in this thread | | | Date | Mon, 04 Aug 2014 18:36:04 +0200 | From | Takashi Iwai <> | Subject | Re: [PATCH v2] Hibernate: check unsafe page should not in e820 reserved region |
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At Mon, 4 Aug 2014 23:23:21 +0800, Lee, Chun-Yi wrote: > > When the machine doesn't well handle the e820 persistent when hibernate > resuming, then it may causes page fault when writing image to snapshot > buffer: > > [ 17.929495] BUG: unable to handle kernel paging request at ffff880069d4f000 > [ 17.933469] IP: [<ffffffff810a1cf0>] load_image_lzo+0x810/0xe40 > [ 17.933469] PGD 2194067 PUD 77ffff067 PMD 2197067 PTE 0 > [ 17.933469] Oops: 0002 [#1] SMP > ... > > The ffff880069d4f000 page is in e820 reserved region of resume boot > kernel: > > [ 0.000000] BIOS-e820: [mem 0x0000000069d4f000-0x0000000069e12fff] reserved > ... > [ 0.000000] PM: Registered nosave memory: [mem 0x69d4f000-0x69e12fff] > > So snapshot.c mark the pfn to forbidden pages map. But, this > page is also in the memory bitmap in snapshot image because it's an > original page used by image kernel, so it will also mark as an > unsafe(free) page in prepare_image(). > > That means the page in e820 when resuming mark as "forbidden" and > "free", it causes get_buffer() treat it as an allocated unsafe page. > Then snapshot_write_next() return this page to load_image, load_image > writing content to this address, but this page didn't really allocated > . So, we got page fault. > > Although the root cause is from BIOS, I think aggressive check and > significant message in kernel will better then a page fault for > issue tracking, especially when serial console unavailable. > > This patch adds code in mark_unsafe_pages() for check does free pages in > nosave region. If so, then it print message and return fault to stop whole > S4 resume process: > > [ 8.166004] PM: Image loading progress: 0% > [ 8.658717] PM: 0x6796c000 in e820 nosave region: [mem 0x6796c000-0x6796cfff] > [ 8.918737] PM: Read 2511940 kbytes in 1.04 seconds (2415.32 MB/s) > [ 8.926633] PM: Error -14 resuming > [ 8.933534] PM: Failed to load hibernation image, recovering. > > v2: > + removed empty check of nosave_regions list. > + fixed the typo of "region" in code for error message and patch comment. > > Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net> > Cc: Len Brown <len.brown@intel.com> > Cc: Takashi Iwai <tiwai@suse.de>
Looks good to me, feel free to take my tag, Reviewed-by: Takashi Iwai <tiwai@suse.de>
Takashi
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