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Subject: Re: [PATCH v2 3/3] kasan: arm64: Fix pcpu_page_first_chunk crash with
 KASAN_VMALLOC
To:     Marco Elver <elver@google.com>
CC:     Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will@kernel.org>,
        Andrey Ryabinin <ryabinin.a.a@gmail.com>,
        Andrey Konovalov <andreyknvl@gmail.com>,
        Dmitry Vyukov <dvyukov@google.com>,
        <linux-arm-kernel@lists.infradead.org>,
        <linux-kernel@vger.kernel.org>, <kasan-dev@googlegroups.com>,
        <linux-mm@kvack.org>
References: <20210720025105.103680-1-wangkefeng.wang@huawei.com>
 <20210720025105.103680-4-wangkefeng.wang@huawei.com>
 <YPlP6h4O1WA0NVDs@elver.google.com>
From:   Kefeng Wang <wangkefeng.wang@huawei.com>
Message-ID: <99a9334e-ccda-dde9-954f-6717946324f8@huawei.com>
Date:   Thu, 22 Jul 2021 20:14:33 +0800
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On 2021/7/22 19:00, Marco Elver wrote:
> On Tue, Jul 20, 2021 at 10:51AM +0800, Kefeng Wang wrote:
>> With KASAN_VMALLOC and NEED_PER_CPU_PAGE_FIRST_CHUNK, it crashs,
>>
>> Unable to handle kernel paging request at virtual address ffff7000028f2000
>> ...
>> swapper pgtable: 64k pages, 48-bit VAs, pgdp=0000000042440000
>> [ffff7000028f2000] pgd=000000063e7c0003, p4d=000000063e7c0003, pud=000000063e7c0003, pmd=000000063e7b0003, pte=0000000000000000
>> Internal error: Oops: 96000007 [#1] PREEMPT SMP
>> Modules linked in:
>> CPU: 0 PID: 0 Comm: swapper Not tainted 5.13.0-rc4-00003-gc6e6e28f3f30-dirty #62
>> Hardware name: linux,dummy-virt (DT)
>> pstate: 200000c5 (nzCv daIF -PAN -UAO -TCO BTYPE=--)
>> pc : kasan_check_range+0x90/0x1a0
>> lr : memcpy+0x88/0xf4
>> sp : ffff80001378fe20
>> ...
>> Call trace:
>>   kasan_check_range+0x90/0x1a0
>>   pcpu_page_first_chunk+0x3f0/0x568
>>   setup_per_cpu_areas+0xb8/0x184
>>   start_kernel+0x8c/0x328
>>
>> The vm area used in vm_area_register_early() has no kasan shadow memory,
>> Let's add a new kasan_populate_early_vm_area_shadow() function to populate
>> the vm area shadow memory to fix the issue.
>>
>> Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
> Acked-by: Marco Elver <elver@google.com>
>
> for the kasan bits.
Thanks Marco.