Re: arm32: panic in move_freepages (Was [PATCH v2 0/4] arm64: drop pfn_valid_within() and simplify pfn_valid())

From: David Hildenbrand <david@redhat.com>
To: Mike Rapoport <rppt@kernel.org>,
	Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: linux-arm-kernel@lists.infradead.org,
	Andrew Morton <akpm@linux-foundation.org>,
	Anshuman Khandual <anshuman.khandual@arm.com>,
	Ard Biesheuvel <ardb@kernel.org>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Marc Zyngier <maz@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Mike Rapoport <rppt@linux.ibm.com>, Will Deacon <will@kernel.org>,
	kvmarm@lists.cs.columbia.edu, linux-kernel@vger.kernel.org,
	linux-mm@kvack.org
Subject: Re: arm32: panic in move_freepages (Was [PATCH v2 0/4] arm64: drop pfn_valid_within() and simplify pfn_valid())
Date: Mon, 3 May 2021 10:07:01 +0200	[thread overview]
Message-ID: <24b37c01-fc75-d459-6e61-d67e8f0cf043@redhat.com> (raw)
In-Reply-To: <YI+XrAg4KOzOyt7c@kernel.org>

On 03.05.21 08:26, Mike Rapoport wrote:
> On Fri, Apr 30, 2021 at 07:24:37PM +0800, Kefeng Wang wrote:
>>
>>
>> On 2021/4/30 17:51, Mike Rapoport wrote:
>>> On Thu, Apr 29, 2021 at 06:22:55PM +0800, Kefeng Wang wrote:
>>>>
>>>> On 2021/4/29 14:57, Mike Rapoport wrote:
>>>>
>>>>>>> Do you use SPARSMEM? If yes, what is your section size?
>>>>>>> What is the value if CONFIG_FORCE_MAX_ZONEORDER in your configuration?
>>>>>> Yes,
>>>>>>
>>>>>> CONFIG_SPARSEMEM=y
>>>>>>
>>>>>> CONFIG_SPARSEMEM_STATIC=y
>>>>>>
>>>>>> CONFIG_FORCE_MAX_ZONEORDER = 11
>>>>>>
>>>>>> CONFIG_PAGE_OFFSET=0xC0000000
>>>>>> CONFIG_HAVE_ARCH_PFN_VALID=y
>>>>>> CONFIG_HIGHMEM=y
>>>>>> #define SECTION_SIZE_BITS    26
>>>>>> #define MAX_PHYSADDR_BITS    32
>>>>>> #define MAX_PHYSMEM_BITS     32
>>>>
>>>>
>>>> With the patch,  the addr is aligned, but the panic still occurred,
>>>
>>> Is this the same panic at move_freepages() for range [de600, de7ff]?
>>>
>>> Do you enable CONFIG_ARM_LPAE?
>>
>> no, the CONFIG_ARM_LPAE is not set, and yes with same panic at
>> move_freepages at
>>
>> start_pfn/end_pfn [de600, de7ff], [de600000, de7ff000] :  pfn =de600, page
>> =ef3cc000, page-flags = ffffffff,  pfn2phy = de600000
>>
>>>> __free_memory_core, range: 0xb0200000 - 0xc0000000, pfn: b0200 - b0200
>>>> __free_memory_core, range: 0xcc000000 - 0xdca00000, pfn: cc000 - b0200
>>>> __free_memory_core, range: 0xde700000 - 0xdea00000, pfn: de700 - b0200
> 
> Hmm, [de600, de7ff] is not added to the free lists which is correct. But
> then it's unclear how the page for de600 gets to move_freepages()...
> 
> Can't say I have any bright ideas to try here...

Are we missing some checks (e.g., PageReserved()) that 
pfn_valid_within() would have "caught" before?

-- 
Thanks,

David / dhildenb