On Thu, Nov 29, 2018 at 03:00:45PM +0000, Juergen Gross wrote: > On 29/11/2018 15:32, Kirill A. Shutemov wrote: > > On Thu, Nov 29, 2018 at 02:24:47PM +0000, Kirill A. Shutemov wrote: > >> On Thu, Nov 29, 2018 at 01:35:17PM +0000, Juergen Gross wrote: > >>> On 29/11/2018 14:26, Kirill A. Shutemov wrote: > >>>> On Thu, Nov 29, 2018 at 09:41:25AM +0000, Juergen Gross wrote: > >>>>> On 29/11/2018 02:22, Hans van Kranenburg wrote: > >>>>>> Hi, > >>>>>> > >>>>>> As also seen at: > >>>>>> https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=914951 > >>>>>> > >>>>>> Attached there are two serial console output logs. One is starting with > >>>>>> Xen 4.11 (from debian unstable) as dom0, and the other one without Xen. > >>>>>> > >>>>>> [ 2.085543] BUG: unable to handle kernel paging request at > >>>>>> ffff888d9fffc000 > >>>>>> [ 2.085610] PGD 200c067 P4D 200c067 PUD 0 > >>>>>> [ 2.085674] Oops: 0000 [#1] SMP NOPTI > >>>>>> [ 2.085736] CPU: 1 PID: 1 Comm: swapper/0 Not tainted > >>>>>> 4.19.0-trunk-amd64 #1 Debian 4.19.5-1~exp1+pvh1 > >>>>>> [ 2.085823] Hardware name: HP ProLiant DL360 G7, BIOS P68 05/21/2018 > >>>>>> [ 2.085895] RIP: e030:ptdump_walk_pgd_level_core+0x1fd/0x490 > >>>>>> [...] > >>>>> > >>>>> The offending stable commit is 4074ca7d8a1832921c865d250bbd08f3441b3657 > >>>>> ("x86/mm: Move LDT remap out of KASLR region on 5-level paging"), this > >>>>> is commit d52888aa2753e3063a9d3a0c9f72f94aa9809c15 upstream. > >>>>> > >>>>> Current upstream kernel is booting fine under Xen, so in general the > >>>>> patch should be fine. Using an upstream kernel built from above commit > >>>>> (with the then needed Xen fixup patch 1457d8cf7664f34c4ba534) is fine, > >>>>> too. > >>>>> > >>>>> Kirill, are you aware of any prerequisite patch from 4.20 which could be > >>>>> missing in 4.19.5? > >>>> > >>>> I'm not. > >>>> > >>>> Let me look into this. > >>>> > >>> > >>> What is making me suspicious is the failure happening just after > >>> releasing the init memory. Maybe there is an access to .init.data > >>> segment or similar? The native kernel booting could be related to the > >>> usage of 2M mappings not being available in a PV-domain. > >> > >> Ahh.. Could you test this: > >> > >> diff --git a/arch/x86/mm/dump_pagetables.c b/arch/x86/mm/dump_pagetables.c > >> index a12afff146d1..7dec63ec7aab 100644 > >> --- a/arch/x86/mm/dump_pagetables.c > >> +++ b/arch/x86/mm/dump_pagetables.c > >> @@ -496,7 +496,7 @@ static inline bool is_hypervisor_range(int idx) > >> * ffff800000000000 - ffff87ffffffffff is reserved for > >> * the hypervisor. > >> */ > >> - return (idx >= pgd_index(__PAGE_OFFSET) - 16) && > >> + return (idx >= pgd_index(__PAGE_OFFSET) - 17) && > >> (idx < pgd_index(__PAGE_OFFSET)); > >> #else > >> return false; > > > > Or, better, this: > > That makes it boot again! > > Any idea why upstream doesn't need it? Nope. I'll prepare a proper fix. -- Kirill A. Shutemov
