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Date: Sun, 14 Jan 2018 14:07:56 +0100
From: Ingo Molnar <mingo@kernel.org>
To: hpa@zytor.com, dvyukov@google.com, tglx@linutronix.de,
        aryabinin@virtuozzo.com, glider@google.com,
        linux-kernel@vger.kernel.org, xiaolong.ye@intel.com
Cc: linux-tip-commits@vger.kernel.org
Subject: Re: [tip:x86/mm] x86/kasan: Panic if there is not enough memory to
 boot
Message-ID: <20180114130756.zkysoiwaqfso2ml4@gmail.com>
References: <20180110153602.18919-1-aryabinin@virtuozzo.com>
 <tip-74b61d1fb59bed3a6608161b05f2c0f5cb71acf6@git.kernel.org>
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* tip-bot for Andrey Ryabinin <tipbot@zytor.com> wrote:

> Commit-ID:  74b61d1fb59bed3a6608161b05f2c0f5cb71acf6
> Gitweb:     https://git.kernel.org/tip/74b61d1fb59bed3a6608161b05f2c0f5cb71acf6
> Author:     Andrey Ryabinin <aryabinin@virtuozzo.com>
> AuthorDate: Wed, 10 Jan 2018 18:36:02 +0300
> Committer:  Thomas Gleixner <tglx@linutronix.de>
> CommitDate: Sun, 14 Jan 2018 12:59:51 +0100
> 
> x86/kasan: Panic if there is not enough memory to boot
> 
> Currently KASAN doesn't panic in case it don't have enough memory
> to boot. Instead, it crashes in some random place:
> 
>  kernel BUG at arch/x86/mm/physaddr.c:27!
> 
>  RIP: 0010:__phys_addr+0x268/0x276
>  Call Trace:
>   kasan_populate_shadow+0x3f2/0x497
>   kasan_init+0x12e/0x2b2
>   setup_arch+0x2825/0x2a2c
>   start_kernel+0xc8/0x15f4
>   x86_64_start_reservations+0x2a/0x2c
>   x86_64_start_kernel+0x72/0x75
>   secondary_startup_64+0xa5/0xb0
> 
> Use memblock_virt_alloc_try_nid() for allocations without failure
> fallback. It will panic with an out of memory message.
> 
> Reported-by: kernel test robot <xiaolong.ye@intel.com>
> Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> Acked-by: Dmitry Vyukov <dvyukov@google.com>
> Cc: kasan-dev@googlegroups.com
> Cc: Alexander Potapenko <glider@google.com>
> Cc: lkp@01.org
> Link: https://lkml.kernel.org/r/20180110153602.18919-1-aryabinin@virtuozzo.com

I think this commit should be in tip:x86/pti for dependency reasons, to get 
backported automatically. I suspect we want the same KASAN robustness in -stable.

If this patch is too high risk and should be in x86/mm, then it should still be 
x86/pti based, to allow later merging into x86/pti.

The latest already-upstream commit of x86/pti is de791821c295, and this commit 
applies cleanly to that base.

Thanks,

	Ingo