Re: [linux-next20260917] BUG: Bad page map in process

[Vernon Yang <vernon2gm@gmail.com>]

On Fri, Sep 18, 2026 at 12:38:29PM +0530, Venkat Rao Bagalkote wrote:
> Greetings!!!
>
> IBM CI has reported following boot warning on Power11 pseries machine
> running linux-next 7.3.0-rc3-next-20260917.
>
>
> Traces:
>
> [    4.944846] BUG: Bad page map in process rtas_errd pte:c00000001fff0786
> [    4.944850] pgd:8000000064e76009 p4d:8000000064e76009
> pud:8000000064013009 pmd:8000000064011009
> [    4.944858] addr:00003fffa9382000 vm_flags:080000fb
> anon_vma:0000000000000000 mapping:c0000000054443a0 index:1fff0
> [    4.944865] file:mem fault:0x0 mmap:0x0 mmap_prepare: mmap_mem_prepare
> read_folio:0x0
> [    4.944875] CPU: 17 UID: 0 PID: 773 Comm: rtas_errd Not tainted
> 7.3.0-rc3-next-20260917 #1 PREEMPT(lazy)
> [    4.944877] Hardware name: IBM,9080-HEX Power11 (architected) 0x820200
> 0xf000007 of:IBM,FW1110.01 (NH1110_069) hv:phyp pSeries
> [    4.944879] Call Trace:
> [    4.944879] [c00000001791b4e0] [c00000000135a92c]
> dump_stack_lvl+0x8c/0xf0 (unreliable)
> [    4.944885] [c00000001791b510] [c0000000006708c0]
> print_bad_page_map.part.0.constprop.0+0x18c/0x260
> [    4.944887] [c00000001791b5f0] [c000000000674fa4]
> vm_normal_page+0x140/0x17c
> [    4.944890] [c00000001791b630] [c00000000067648c]
> zap_present_ptes.constprop.0+0x9c/0x9ac
> [    4.944893] [c00000001791b700] [c000000000677038]
> zap_pte_range+0x29c/0x5f4
> [    4.944895] [c00000001791b840] [c000000000677500]
> zap_pmd_range.isra.0+0x170/0x310
> [    4.944898] [c00000001791b8d0] [c000000000677a00]
> __zap_vma_range+0x360/0x4cc
> [    4.944900] [c00000001791b980] [c0000000006780e0] unmap_vmas+0x98/0x1a0
> [    4.944903] [c00000001791ba10] [c0000000006b0f68] unmap_region+0x94/0x108
> [    4.944905] [c00000001791bad0] [c0000000006b1c7c]
> vms_complete_munmap_vmas+0x11c/0x2c8
> [    4.944907] [c00000001791bb60] [c0000000006b273c]
> do_vmi_align_munmap+0x1ac/0x1f8
> [    4.944909] [c00000001791bca0] [c0000000006b52c0] __vm_munmap+0xdc/0x1fc
> [    4.944911] [c00000001791bd60] [c00000000068b154] sys_munmap+0x28/0x3c
> [    4.944913] [c00000001791bd80] [c000000000032150]
> system_call_exception+0x190/0x4b0
> [    4.944916] [c00000001791be50] [c00000000000d05c]
> system_call_vectored_common+0x15c/0x2ec
> [    4.944919] ---- interrupt: 3000 at 0x3fffa9143754
> [    4.944920] NIP:  00003fffa9143754 LR: 00003fffa9143754 CTR:
> 0000000000000000
> [    4.944922] REGS: c00000001791be80 TRAP: 3000   Not tainted
> (7.3.0-rc3-next-20260917)
> [    4.944923] MSR:  800000000280f033 <SF,VEC,VSX,EE,PR,FP,ME,IR,DR,RI,LE> 
> CR: 44002408  XER: 00000000
> [    4.944928] IRQMASK: 0
> [    4.944928] GPR00: 000000000000005b 00003fffc0a69a20 00003fffa9237d00
> 00003fffa9382000
> [    4.944928] GPR04: 0000000000001000 0000000000000002 0000000000000000
> 0000000000000001
> [    4.944928] GPR08: 000000000000001b 0000000000000000 0000000000000000
> 0000000000000000
> [    4.944928] GPR12: 0000000000000000 00003fffa937f860 0000000000000000
> 00003fffa9383550
> [    4.944928] GPR16: 0000000000000000 00003fffc0a69cd8 00003fffc0a69ca0
> 68746150706d7544
> [    4.944928] GPR20: 00003fffc0a69c10 0068746150706d75 636170614364656c
> 747365526f747541
> [    4.944928] GPR24: 000000013ad9e130 00003fffc0a6a0d8 6d726f6674616c50
> 00003fffa92f5ee0
> [    4.944928] GPR28: 00003fffa9382000 000000001fff0000 0000000000000009
> 0000000000100000
> [    4.944945] NIP [00003fffa9143754] 0x3fffa9143754
> [    4.944946] LR [00003fffa9143754] 0x3fffa9143754
> [    4.944947] ---- interrupt: 3000

Hi Venkat,

Thanks for reporting this bug. I also reproduced this phenomenon on my
local machine and found that Lorenzo[1] has already fixed the bug, and
Mike[2] also provided a detailed analysis.

[1] https://lore.kernel.org/linux-mm/aq06hcheI4OGi_3A@gremlin/
[2] https://lore.kernel.org/linux-mm/aquz9Z9JrK_H_E0g@kernel.org/

--
Cheers,
Vernon