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From: Mike Rapoport <rppt@linux.ibm.com>
To: Qian Cai <quic_qiancai@quicinc.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	David Hildenbrand <david@redhat.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Anshuman Khandual <anshuman.khandual@arm.com>,
	Ard Biesheuvel <ardb@kernel.org>,
	Linux Memory Management List <linux-mm@kvack.org>,
	Will Deacon <will@kernel.org>, Marc Zyngier <maz@kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Linux ARM <linux-arm-kernel@lists.infradead.org>
Subject: Re: Arm64 crash while reading memory sysfs
Date: Thu, 27 May 2021 19:22:00 +0300	[thread overview]
Message-ID: <YK/HKMgajBCwpLt8@linux.ibm.com> (raw)
In-Reply-To: <ce5a5920-3046-21b5-42c0-2237ec1eef13@quicinc.com>

On Thu, May 27, 2021 at 10:33:13AM -0400, Qian Cai wrote:
> 
> 
> On 5/27/2021 4:56 AM, Mike Rapoport wrote:
> > Let's drop memblock=debug for now and add this instead:
> 
> [    0.000000][    T0] Booting Linux on physical CPU 0x0000000000 [0x503f0002]
> [    0.000000][    T0] Linux version 5.13.0-rc3-next-20210526+ (root@admin5) (gcc (Ubuntu 9.3.0-17ubuntu1~20.04) 9.3.0, GNU ld (GNU Binutils for Ubuntu) 2.34) #31 SMP Thu May 27 12:32:40 UTC 2021
> [    0.000000][    T0] Inode-cache hash table entries: 4194304 (order: 9, 33554432 bytes, linear)
> [    0.000000][    T0] mem auto-init: stack:off, heap alloc:on, heap free:off
> [    0.000000][    T0] MEMBLOCK configuration:
> [    0.000000][    T0]  memory size = 0x0000001ff0000000 reserved size = 0x0000000421e33ae8
> [    0.000000][    T0]  memory.cnt  = 0xc
> [    0.000000][    T0] Memory: 777216K/133955584K available (17984K kernel code, 118722K rwdata, 4416K rodata, 6080K init, 67276K bss, 17379072K reserved, 0K cma-reserved)

I still cannot understand where most of the memory disappeared, but it
seems entirely different issue.
 
> > Sorry, I've missed that the BUG is apparently triggered for pfn + i. Can
> > you please try this instead:
> 
> [  259.216661][ T1417] test_pages_in_a_zone: pfn 8000 is not valid
> [  259.226547][ T1417] page:00000000f4aa8c5c is uninitialized and poisoned
> [  259.226560][ T1417] page dumped because: VM_BUG_ON_PAGE(PagePoisoned(p))

Can you please try Anshuman's patch "arm64/mm: Drop HAVE_ARCH_PFN_VALID":

https://lore.kernel.org/lkml/1621947349-25421-1-git-send-email-anshuman.khandual@arm.com

It seems to me that the check for memblock_is_memory() in
arm64::pfn_valid() is what makes init_unavailable_range() to bail out for
section parts that are not actually populated and then we have
VM_BUG_ON_PAGE(PagePoisoned(p)) for these pages.

-- 
Sincerely yours,
Mike.

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  reply	other threads:[~2021-05-27 17:58 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-25 15:25 Arm64 crash while reading memory sysfs Qian Cai (QUIC)
2021-05-25 15:37 ` David Hildenbrand
2021-05-26  6:40 ` Mike Rapoport
2021-05-26 12:09   ` Qian Cai (QUIC)
2021-05-26 13:04     ` Catalin Marinas
2021-05-26 17:25       ` Mike Rapoport
2021-05-26 17:24     ` Mike Rapoport
2021-05-27  0:16       ` Qian Cai
2021-05-27  0:31         ` Andrew Morton
2021-05-27  7:25           ` Stephen Rothwell
2021-05-27  8:56         ` Mike Rapoport
2021-05-27 14:33           ` Qian Cai
2021-05-27 16:22             ` Mike Rapoport [this message]
2021-05-27 17:00               ` Qian Cai
2021-05-27 17:12               ` David Hildenbrand
2021-05-27 17:50               ` Catalin Marinas
2021-05-27 22:56                 ` Andrew Morton
2021-05-28  5:13                   ` Mike Rapoport
2021-06-08  7:06                     ` Anshuman Khandual
2021-06-14  8:25                       ` Mike Rapoport
2021-06-15  0:13                         ` Andrew Morton
2021-06-15  6:05                           ` Mike Rapoport

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