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Date:   Fri, 29 Apr 2022 14:09:52 +0200
From:   Heiko Carstens <hca@linux.ibm.com>
To:     Guenter Roeck <linux@roeck-us.net>
Cc:     Andrew Morton <akpm@linux-foundation.org>, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org,
        "Liam R. Howlett" <Liam.Howlett@oracle.com>
Subject: Re: [PATCH] mapletree-vs-khugepaged
Message-ID: <YmvVkKXJWBoGqWFx@osiris>
References: <20220428172040.GA3623323@roeck-us.net>
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On Thu, Apr 28, 2022 at 10:20:40AM -0700, Guenter Roeck wrote:
> On Wed, Apr 27, 2022 at 03:10:45PM -0700, Andrew Morton wrote:
> > Fix mapletree for patch series "Make khugepaged collapse readonly FS THP
> > more consistent", v3.
> > 
> > Cc: Liam R. Howlett <Liam.Howlett@oracle.com>
> > Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
> 
> This patch causes all my sparc64 boot tests to fail. Bisect and crash logs
> attached.
> 
> Guenter
> 
> ---
> [   12.624703] Unable to handle kernel paging request at virtual address 0e00000000000000
> [   12.624793] tsk->{mm,active_mm}->context = 0000000000000005
> [   12.624823] tsk->{mm,active_mm}->pgd = fffff800048b8000
> [   12.624849]               \|/ ____ \|/
> [   12.624849]               "@'/ .. \`@"
> [   12.624849]               /_| \__/ |_\
> [   12.624849]                  \__U_/
> [   12.624874] init(1): Oops [#1]
> [   12.625194] CPU: 0 PID: 1 Comm: init Not tainted 5.18.0-rc4-next-20220428 #1
> [   12.625421] TSTATE: 0000009911001606 TPC: 00000000005e6330 TNPC: 00000000005e6334 Y: 00000000    Not tainted
> [   12.625455] TPC: <mmap_region+0x150/0x700>
> [   12.625503] g0: 0000000000619a00 g1: 0000000000000000 g2: fffff8000488b200 g3: 0000000000000000
> [   12.625537] g4: fffff8000414a9a0 g5: fffff8001dd3e000 g6: fffff8000414c000 g7: 0000000000000000
> [   12.625569] o0: 0000000000000000 o1: 0000000000000000 o2: 0000000001167b68 o3: 0000000000f51bb8
> [   12.625601] o4: fffff80100301fff o5: fffff8000414fc20 sp: fffff8000414f341 ret_pc: 00000000005e6310
> [   12.625630] RPC: <mmap_region+0x130/0x700>
> [   12.625692] l0: fffff8000488b260 l1: 000000000000008b l2: fffff80100302000 l3: 0000000000000000
> [   12.625725] l4: fffff80100301fff l5: 0000000000000000 l6: 30812c2a1dd8556f l7: fffff8000414b438
> [   12.625762] i0: fffff800044f58a0 i1: fffff801001ec000 i2: 0e00000000000000 i3: 0000000000000075
> [   12.625795] i4: 0000000000000000 i5: fffff8000414fde0 i6: fffff8000414f461 i7: 00000000005e6c58
> [   12.625833] I7: <do_mmap+0x378/0x500>
> [   12.625906] Call Trace:
> [   12.626006] [<00000000005e6c58>] do_mmap+0x378/0x500
> [   12.626092] [<00000000005bdc98>] vm_mmap_pgoff+0x78/0x100
> [   12.626112] [<00000000005e3d24>] ksys_mmap_pgoff+0x164/0x1c0
> [   12.626129] [<0000000000406294>] linux_sparc_syscall+0x34/0x44
> [   12.626198] Disabling lock debugging due to kernel taint
> [   12.626286] Caller[00000000005e6c58]: do_mmap+0x378/0x500
> [   12.626335] Caller[00000000005bdc98]: vm_mmap_pgoff+0x78/0x100
> [   12.626354] Caller[00000000005e3d24]: ksys_mmap_pgoff+0x164/0x1c0
> [   12.626371] Caller[0000000000406294]: linux_sparc_syscall+0x34/0x44
> [   12.626390] Caller[fffff8010001d88c]: 0xfffff8010001d88c
> [   12.626537] Instruction DUMP:
> [   12.626567]  a6100008
> [   12.626678]  02c68006
> [   12.626685]  01000000
> [   12.626690] <c25e8000>
> [   12.626696]  80a04012
> [   12.626701]  22600077
> [   12.626707]  c25ea088
> [   12.626712]  22c4c00a
> [   12.626717]  f277a7c7
> [   12.626728]
> [   12.627169] Kernel panic - not syncing: Attempted to kill init! exitcode=0x00000009

FWIW, same on s390 - linux-next is completely broken. Note: I didn't
bisect, but given that the call trace, and even the failing address
match, I'm quite confident it is the same reason.

Unable to handle kernel pointer dereference in virtual kernel address space
Failing address: 0e00000000000000 TEID: 0e00000000000803
Fault in home space mode while using kernel ASCE.
AS:00000000bac44007 R3:00000001ffff0007 S:00000001fffef800 P:000000000000003d
Oops: 0038 ilc:3 [#1] SMP
CPU: 3 PID: 79757 Comm: pt_upgrade_race Tainted: G            E K   5.18.0-20220428.rc4.git500.bdc61aad77fa.300.fc35.s390x+next #1
Hardware name: IBM 2964 NC9 702 (z/VM 6.4.0)
Krnl PSW : 0704c00180000000 00000000b912c9a2 (mmap_region+0x1a2/0x8a8)
           R:0 T:1 IO:1 EX:1 Key:0 M:1 W:0 P:0 AS:3 CC:0 PM:0 RI:0 EA:3
Krnl GPRS: 0000000000000000 0e00000000000000 0000000000000000 0000000000000000
           ffffffffffffffff 000000000000000f 00000380016b3d98 0000080000100000
           000000008364c100 0000080000000000 0000000000100077 0e00000000000000
           00000000909da100 00000380016b3c58 00000000b912c982 00000380016b3b40
Krnl Code: 00000000b912c992: a774002c          brc     7,00000000b912c9ea
           00000000b912c996: ecb80225007c      cgij    %r11,0,8,00000000b912cde0
          #00000000b912c99c: e310f0f80004      lg      %r1,248(%r15)
          >00000000b912c9a2: e37010000020      cg      %r7,0(%r1)
           00000000b912c9a8: a784010b          brc     8,00000000b912cbbe
           00000000b912c9ac: e310f0e80004      lg      %r1,232(%r15)
           00000000b912c9b2: ec180013007c      cgij    %r1,0,8,00000000b912c9d8
           00000000b912c9b8: e310f0e80004      lg      %r1,232(%r15)
Call Trace:
 [<00000000b912c9a2>] mmap_region+0x1a2/0x8a8
([<00000000b912c982>] mmap_region+0x182/0x8a8)
 [<00000000b912d492>] do_mmap+0x3ea/0x4c8
 [<00000000b90fb9cc>] vm_mmap_pgoff+0xd4/0x170
 [<00000000b9129c9a>] ksys_mmap_pgoff+0x62/0x238
 [<00000000b912a034>] __s390x_sys_old_mmap+0x74/0x98
 [<00000000b9a78ff8>] __do_syscall+0x1d8/0x200
 [<00000000b9a872a2>] system_call+0x82/0xb0
Last Breaking-Event-Address:
 [<00000000b9b9e678>] __s390_indirect_jump_r14+0x0/0xc
Kernel panic - not syncing: Fatal exception: panic_on_oops