[Bug 213069] New: kernel BUG at arch/powerpc/include/asm/book3s/64/hash-4k.h:147! Oops: Exception in kernel mode, sig: 5 [#1]

https://bugzilla.kernel.org/show_bug.cgi?id=213069

            Bug ID: 213069
           Summary: kernel BUG at
                    arch/powerpc/include/asm/book3s/64/hash-4k.h:147!
                    Oops: Exception in kernel mode, sig: 5 [#1]
           Product: Platform Specific/Hardware
           Version: 2.5
    Kernel Version: 5.13-rc1
          Hardware: PPC-64
                OS: Linux
              Tree: Mainline
            Status: NEW
          Severity: normal
          Priority: P1
         Component: PPC-64
          Assignee: platform_ppc-64@kernel-bugs.osdl.org
          Reporter: erhard_f@mailbox.org
        Regression: No

Created attachment 296753
  --> https://bugzilla.kernel.org/attachment.cgi?id=296753&action=edit
kernel .config (5.13-rc1, PowerMac G5 11,2)

Got this on my PowerMac G5 11,2 with v5.13-rc1 + few debug options on. The bug
was too early for netconsole to kick in so I took a photo and transcribed it.

[...]
kmemleak: Kernel memory leak detector initialized (mem pool available: 15805)
kmemleak: Automatic memory scanning thread started
debug_vm_pgtable: [debug_vm_pgtable         ]: Validating architecture page
table helpers
------------[ cut here ]------------
kernel BUG at arch/powerpc/include/asm/book3s/64/hash-4k.h:147!
Oops: Exception in kernel mode, sig: 5 [#1]
BE PAGE_SIZE=4K MMU=Hash SMP NR_CPUS=4 NUMA PowerMac
Modules linked in:
CPU: 0 PID: 1 Comm: swapper/0 Tainted: G        W         5.13.0-rc1-PowerMacG5
#2
NIP:  c00000000003d6fc LR: c000000001024bc8 CTR: c0000000000f778c

34 more lines

https://bugzilla.kernel.org/show_bug.cgi?id=213069

--- Comment #1 from Erhard F. (erhard_f@mailbox.org) ---

The bug occurs with DEBUG_VM_PGTABLE=y. When DEBUG_VM_PGTABLE is not set the
kernel boots fine.

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https://bugzilla.kernel.org/show_bug.cgi?id=213069

Christophe Leroy (christophe.leroy@csgroup.eu) changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |christophe.leroy@csgroup.eu

--- Comment #2 from Christophe Leroy (christophe.leroy@csgroup.eu) ---

The bug is not in powerpc but in function pmd_basic_tests() in
mm/debug_vm_pgtable.c
(https://elixir.bootlin.com/linux/v5.13-rc1/source/mm/debug_vm_pgtable.c#L146)

pfn_pmd() should not be called before the has_transparent_hugepage()
verification.

Same problem in pmd_advanced_tests()

And there is the exact same issue with PUD tests with pfn_pud() function.

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Michael Ellerman (michael@ellerman.id.au) changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED
                 CC|                            |michael@ellerman.id.au

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--- Comment #3 from Christophe Leroy (christophe.leroy@csgroup.eu) ---

Patch proposed by Anshuman, to be tested:

https://lore.kernel.org/linuxppc-dev/bug-213069-206035@https.bugzilla.kernel.org%2F/T/#m82f2974b813c4d3a085b0cd2ac3d5b732a362e68

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Michael Ellerman (michael@ellerman.id.au) changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|---                         |CODE_FIX

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Erhard F. (erhard_f@mailbox.org) changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|RESOLVED                    |REOPENED
         Resolution|CODE_FIX                    |---

--- Comment #4 from Erhard F. (erhard_f@mailbox.org) ---

I applied the patch on top of 5.13-rc4 but it didn't work out unfortunately.

Still getting the same
kernel BUG at arch/powerpc/include/asm/book3s/64/hash-4k.h:147!
Oops: Exception in kernel mode, sig: 5 [#1]
...

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Erhard F. (erhard_f@mailbox.org) changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|REOPENED                    |RESOLVED
         Resolution|---                         |PATCH_ALREADY_AVAILABLE

--- Comment #5 from Erhard F. (erhard_f@mailbox.org) ---

Works now with Anshuman's patch applied:
https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/?id=c0dd65c2e295762fc5ebd11f8da3ac33f1d30788

Thanks!

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