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From: Andrew Morton <akpm@linux-foundation.org>
To: Toshi Kani <toshi.kani@hpe.com>
Cc: gregkh@linuxfoundation.org, linux-mm@kvack.org,
	zhenzhang.zhang@huawei.com, arbab@linux.vnet.ibm.com,
	dan.j.williams@intel.com, abanman@sgi.com, rientjes@google.com,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/2] base/memory, hotplug: fix a kernel oops in show_valid_zones()
Date: Thu, 26 Jan 2017 13:52:54 -0800	[thread overview]
Message-ID: <20170126135254.cbd0bdbe3cdc5910c288ad32@linux-foundation.org> (raw)
In-Reply-To: <20170126214415.4509-3-toshi.kani@hpe.com>

On Thu, 26 Jan 2017 14:44:15 -0700 Toshi Kani <toshi.kani@hpe.com> wrote:

> Reading a sysfs memoryN/valid_zones file leads to the following
> oops when the first page of a range is not backed by struct page.
> show_valid_zones() assumes that 'start_pfn' is always valid for
> page_zone().
> 
>  BUG: unable to handle kernel paging request at ffffea017a000000
>  IP: show_valid_zones+0x6f/0x160
> 
> Since test_pages_in_a_zone() already checks holes, extend this
> function to return 'valid_start' and 'valid_end' for a given range.
> show_valid_zones() then proceeds with the valid range.

This doesn't apply to current mainline due to changes in
zone_can_shift().  Please redo and resend.

Please also update the changelog to provide sufficient information for
others to decide which kernel(s) need the fix.  In particular: under
what circumstances will it occur?  On real machines which real people
own?

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  reply	other threads:[~2017-01-26 21:52 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-01-26 21:44 [PATCH 0/2] fix a kernel oops in reading sysfs valid_zones Toshi Kani
2017-01-26 21:44 ` [PATCH 1/2] mm/memory_hotplug.c: check start_pfn in test_pages_in_a_zone() Toshi Kani
2017-01-26 21:44 ` [PATCH 2/2] base/memory, hotplug: fix a kernel oops in show_valid_zones() Toshi Kani
2017-01-26 21:52   ` Andrew Morton [this message]
2017-01-26 22:26     ` Kani, Toshimitsu
2017-01-27  7:48       ` gregkh
2017-01-27 17:47         ` Kani, Toshimitsu

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