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Date: Sat, 21 Nov 2015 13:49:06 +0200 From: Vassilis Virvilis <vasvir@....demokritos.gr> To: Juergen Gross <jgross@...e.com> Cc: linux-kernel@...r.kernel.org, Toshi Kani <toshi.kani@...com>, "Luis R. Rodriguez" <mcgrof@...e.com> Subject: Re: Hibernate resume bug around 3,18-rc2 - Full PAT support On 11/20/2015 02:23 PM, Juergen Gross wrote: > On 20/11/15 11:04, vasvir@....demokritos.gr wrote: >>> I've just found a potential issue: In case MTRR is disabled by the BIOS >>> the PAT register of the boot processor won't be restored after resume. >>> >>> Can you check whether pr_info("MTRR: Disabled\n") has been executed in >>> early boot? If yes, this might be a BIOS option. >>> >> >> I don't have access right now. I will test it later tonight (This is my >> home machine). >> >> Would $dmesg | grep -i mtrr suffice or I need to look for the mtrr >> somewere else e.g. /proc /sys etc? > > I think grepping for MTRR in dmesg should be enough. kernel 4.3 +nopat also died on the 4th or the 5th hibernate on the familiar (see previously attached image) "Calling lapic..." place. $dmesg | grep -i mtr for 4.3 kernel with notpat [ 0.189113] calling mtrr_if_init+0x0/0x5f @ 1 [ 0.189116] initcall mtrr_if_init+0x0/0x5f returned 0 after 0 usecs [ 0.189222] pmd_set_huge: Cannot satisfy [mem 0xf8000000-0xf8200000] with a huge-page mapping due to MTRR override. [ 0.189559] calling mtrr_init_finialize+0x0/0x3a @ 1 [ 0.189560] initcall mtrr_init_finialize+0x0/0x3a returned 0 after 0 usecs [ 8.994140] mtrr: type mismatch for e0000000,10000000 old: write-back new: write-combining [ 8.994154] Failed to add WC MTRR for [00000000e0000000-00000000efffffff]; performance may suffer. $dmesg | grep -i mtr for 4.3 kernel with default pat enabled [ 0.189368] calling mtrr_if_init+0x0/0x5f @ 1 [ 0.189370] initcall mtrr_if_init+0x0/0x5f returned 0 after 0 usecs [ 0.189478] pmd_set_huge: Cannot satisfy [mem 0xf8000000-0xf8200000] with a huge-page mapping due to MTRR override. [ 0.189814] calling mtrr_init_finialize+0x0/0x3a @ 1 [ 0.189815] initcall mtrr_init_finialize+0x0/0x3a returned 0 after 0 usecs I also checked my BIOS. I found nothing about mtrr. My BIOS manual is ftp://europe.asrock.com/Manual/H97%20Pro4.pdf. Can you see any option about MTRR? Question: If we assume your theory is correct about mtrr/pat, wouldn't lockup/hang reboot every time the system goes to hibernate/resume? Can this assumption explain why the first hibernation/resume cycles in rapid succession after system boot are working and the long ones fail somewhat more consistently? Note: With PAT enabled the system boots up significantly faster. In the weekend I will return to 3.18-rc2 and I will try to verify my bisection is correct. Double guessing your self is a terrible thing... I will also try with nopat and I will run dmesg | grep -i mtr and post results Unless you have any other suggestions... Vassilis -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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