Created attachment 296753 [details] 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 REGS: c0000000025f7840 TRAP: 0700 Tainted: G W (5.13.0-rc1-PowerMacG5) MSR: 9000000000029032 <SF,HV,EE,ME,IR,DR,RI> CR: 44002448 XER: 00000000 IRQMASK: 0 GPR00: c000000001024a5c c0000000025f7ae0 c00000000129f800 c0000000025f7b58 GPR04: 0000000000001000 8000000000000108 0000000000000000 0000000000000001 GPR08: 0000000000000000 0000000000000000 0000000000000008 0000000000000200 GPR12: 0000000024002440 c000000002366000 c00000000001003c 0000000000000000 GPR16: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 GPR20: c0000000011b3388 c000000000b013e8 c0000000011b3108 4000000000000006 GPR24: 4000000000000280 00000000011b3000 0000000000000000 8000000000000105 GPR28: 0000000000001000 ffffffffffffff7f c000000000b01460 80000000011b3108 NIP [c00000000003d6fc] .pfn_pmd+x0x/0x4 LR [c000000001024bc8] .debug_vm_pgtable+0x3f4/0x51c Call Trace: [c0000000025f7ae0] [c000000001024a5c] .debug_vm_pgtable+0x288/0x51c (unreliable) [c0000000025f7bd0] [c00000000000fa58] .do_one_initcall+0x104/0x2c4 [c0000000025f7cb0] [c000000001003dec] .kernel_init_freeable+0x3d4/0x410 [c0000000025f7da0] [c00000000001004c] .kernel_init+0x10/0x15c [c0000000025f7e10] [c00000000000bbf4] .ret_from_kernel_thread+0x58/0x64 Instruction dump: 4bffcd05 60000000 e9210078 e94d0370 7d295279 39400000 4182000c 487d3829 60000000 38210090 7fe3fb78 487dacf4 <0fe00000> 7c0802a6 f8010010 f821ff71 ---[ end trace 21fc0fb84dac9a9b ]--- Kernel panic - not syncing: Attempted to kill init! exitcode=0x00000005 Rebooting in 120 seconds..
The bug occurs with DEBUG_VM_PGTABLE=y. When DEBUG_VM_PGTABLE is not set the kernel boots fine.
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.
Patch proposed by Anshuman, to be tested: https://lore.kernel.org/linuxppc-dev/bug-213069-206035@https.bugzilla.kernel.org%2F/T/#m82f2974b813c4d3a085b0cd2ac3d5b732a362e68
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] ...
Works now with Anshuman's patch applied: https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/?id=c0dd65c2e295762fc5ebd11f8da3ac33f1d30788 Thanks!