Re: [PATCH V6 0/2] mm/debug: Add tests validating architecture page table helpers

[Anshuman Khandual <anshuman.khandual@xxxxxxx>]

On 10/15/2019 08:11 PM, Qian Cai wrote:
> The x86 will crash with linux-next during boot due to this series (v5) with the
> config below plus CONFIG_DEBUG_VM_PGTABLE=y. I am not sure if v6 would address
> it.
> 
> https://raw.githubusercontent.com/cailca/linux-mm/master/x86.config
> 
> [   33.862600][    T1] page:ffffea0009000000 is uninitialized and poisoned
> [   33.862608][    T1] raw: ffffffffffffffff ffffffffffffffff ffffffffffffffff
> ffffff871140][    T1]  ? _raw_spin_unlock_irq+0x27/0x40
> [   33.871140][    T1]  ? rest_init+0x307/0x307
> [   33.871140][    T1]  kernel_init+0x11/0x139
> [   33.871140][    T1]  ? rest_init+0x307/0x307
> [   33.871140][    T1]  ret_from_fork+0x27/0x50
> [   33.871140][    T1] Modules linked in:
> [   33.871140][    T1] ---[ end trace e99d392b0f7befbd ]---
> [   33.871140][    T1] RIP: 0010:alloc_gigantic_page_order+0x3fe/0x490

Hmm, with defconfig (DEBUG_VM=y and DEBUG_VM_PGTABLE=y) it does not crash but
with the config above, it does. Just wondering if it is possible that these
pages might not been initialized yet because DEFERRED_STRUCT_PAGE_INIT=y ?

[   13.898549][    T1] page:ffffea0005000000 is uninitialized and poisoned
[   13.898549][    T1] raw: ffffffffffffffff ffffffffffffffff ffffffffffffffff ffffffffffffffff
[   13.898549][    T1] raw: ffffffffffffffff ffffffffffffffff ffffffffffffffff ffffffffffffffff
[   13.898549][    T1] page dumped because: VM_BUG_ON_PAGE(PagePoisoned(p))
[   13.898549][    T1] ------------[ cut here ]------------
[   13.898549][    T1] kernel BUG at ./include/linux/mm.h:1107!
[   13.898549][    T1] invalid opcode: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN PTI
[   13.898549][    T1] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.4.0-rc3-next-20191015+ #