From: Dave Young <dyoung@redhat.com>
To: Tejun Heo <tj@kernel.org>
Cc: WANG Cong <xiyou.wangcong@gmail.com>,
kexec@lists.infradead.org, tim@edgecast.com,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] percpu: fix chunk range calculation
Date: Tue, 22 Nov 2011 10:48:28 +0800 [thread overview]
Message-ID: <4ECB0D7C.1020700@redhat.com> (raw)
In-Reply-To: <20111121211050.GK25776@google.com>
On 11/22/2011 05:10 AM, Tejun Heo wrote:
> On Fri, Nov 18, 2011 at 10:55:35AM -0800, Tejun Heo wrote:
>> Percpu allocator recorded the cpus which map to the first and last
>> units in pcpu_first/last_unit_cpu respectively and used them to
>> determine the address range of a chunk - e.g. it assumed that the
>> first unit has the lowest address in a chunk while the last unit has
>> the highest address.
>>
>> This simply isn't true. Groups in a chunk can have arbitrary positive
>> or negative offsets from the previous one and there is no guarantee
>> that the first unit occupies the lowest offset while the last one the
>> highest.
>>
>> Fix it by actually comparing unit offsets to determine cpus occupying
>> the lowest and highest offsets. Also, rename pcu_first/last_unit_cpu
>> to pcpu_low/high_unit_cpu to avoid confusion.
>>
>> The chunk address range is used to flush cache on vmalloc area
>> map/unmap and decide whether a given address is in the first chunk by
>> per_cpu_ptr_to_phys() and the bug was discovered by invalid
>> per_cpu_ptr_to_phys() translation for crash_note.
>>
>> Kudos to Dave Young for tracking down the problem.
>>
>> Signed-off-by: Tejun Heo <tj@kernel.org>
>> Reported-by: WANG Cong <xiyou.wangcong@gmail.com>
>> Reported-by: Dave Young <dyoung@redhat.com>
>> LKML-Reference: <4EC21F67.10905@redhat.com>
>> Cc: stable @kernel.org
>
> BTW, waiting for Tested-by. If someone gives me that, I'll push it
> through percpu/for-fixes.
Tested-by: Dave Young <dyoung@redhat.com>
>
> Thanks.
>
--
Thanks
Dave
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WARNING: multiple messages have this Message-ID (diff)
From: Dave Young <dyoung@redhat.com>
To: Tejun Heo <tj@kernel.org>
Cc: WANG Cong <xiyou.wangcong@gmail.com>,
kexec@lists.infradead.org, tim@edgecast.com,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] percpu: fix chunk range calculation
Date: Tue, 22 Nov 2011 10:48:28 +0800 [thread overview]
Message-ID: <4ECB0D7C.1020700@redhat.com> (raw)
In-Reply-To: <20111121211050.GK25776@google.com>
On 11/22/2011 05:10 AM, Tejun Heo wrote:
> On Fri, Nov 18, 2011 at 10:55:35AM -0800, Tejun Heo wrote:
>> Percpu allocator recorded the cpus which map to the first and last
>> units in pcpu_first/last_unit_cpu respectively and used them to
>> determine the address range of a chunk - e.g. it assumed that the
>> first unit has the lowest address in a chunk while the last unit has
>> the highest address.
>>
>> This simply isn't true. Groups in a chunk can have arbitrary positive
>> or negative offsets from the previous one and there is no guarantee
>> that the first unit occupies the lowest offset while the last one the
>> highest.
>>
>> Fix it by actually comparing unit offsets to determine cpus occupying
>> the lowest and highest offsets. Also, rename pcu_first/last_unit_cpu
>> to pcpu_low/high_unit_cpu to avoid confusion.
>>
>> The chunk address range is used to flush cache on vmalloc area
>> map/unmap and decide whether a given address is in the first chunk by
>> per_cpu_ptr_to_phys() and the bug was discovered by invalid
>> per_cpu_ptr_to_phys() translation for crash_note.
>>
>> Kudos to Dave Young for tracking down the problem.
>>
>> Signed-off-by: Tejun Heo <tj@kernel.org>
>> Reported-by: WANG Cong <xiyou.wangcong@gmail.com>
>> Reported-by: Dave Young <dyoung@redhat.com>
>> LKML-Reference: <4EC21F67.10905@redhat.com>
>> Cc: stable @kernel.org
>
> BTW, waiting for Tested-by. If someone gives me that, I'll push it
> through percpu/for-fixes.
Tested-by: Dave Young <dyoung@redhat.com>
>
> Thanks.
>
--
Thanks
Dave
next prev parent reply other threads:[~2011-11-22 2:46 UTC|newest]
Thread overview: 63+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-10-11 23:39 Crash during vmcore_init Tim Hartrick
2011-11-14 13:39 ` WANG Cong
2011-11-14 18:50 ` Tim Hartrick
2011-11-15 8:14 ` Dave Young
2011-11-15 8:14 ` Dave Young
2011-11-15 13:47 ` Américo Wang
2011-11-15 13:47 ` Américo Wang
2011-11-15 13:50 ` Américo Wang
2011-11-15 13:50 ` Américo Wang
2011-11-15 22:32 ` Tim Hartrick
2011-11-15 22:32 ` Tim Hartrick
2011-11-16 2:22 ` Dave Young
2011-11-16 2:22 ` Dave Young
2011-11-16 18:20 ` Tim Hartrick
2011-11-16 18:20 ` Tim Hartrick
2011-11-17 3:30 ` Dave Young
2011-11-17 3:30 ` Dave Young
2011-11-17 4:34 ` Tejun Heo
2011-11-17 4:34 ` Tejun Heo
2011-11-17 4:46 ` Dave Young
2011-11-17 4:46 ` Dave Young
2011-11-17 5:22 ` Tim Hartrick
2011-11-17 7:21 ` Dave Young
2011-11-17 7:21 ` Dave Young
2011-11-17 7:23 ` Tejun Heo
2011-11-17 7:23 ` Tejun Heo
2011-11-17 7:42 ` Américo Wang
2011-11-17 7:42 ` Américo Wang
2011-11-17 16:40 ` Tim Hartrick
2011-11-17 16:40 ` Tim Hartrick
2011-11-18 8:43 ` Dave Young
2011-11-18 8:43 ` Dave Young
2011-11-18 8:45 ` Dave Young
2011-11-18 8:45 ` Dave Young
2011-11-18 18:55 ` [PATCH] percpu: fix chunk range calculation Tejun Heo
2011-11-18 18:55 ` Tejun Heo
2011-11-21 1:45 ` Dave Young
2011-11-21 1:45 ` Dave Young
2011-11-21 16:20 ` Tim Hartrick
2011-11-22 2:52 ` Dave Young
2011-11-22 2:52 ` Dave Young
2011-11-21 17:01 ` Tejun Heo
2011-11-21 17:01 ` Tejun Heo
2011-11-22 3:00 ` Dave Young
2011-11-22 3:00 ` Dave Young
2011-11-22 16:02 ` Tejun Heo
2011-11-22 16:02 ` Tejun Heo
2011-11-21 21:10 ` Tejun Heo
2011-11-21 21:10 ` Tejun Heo
2011-11-22 2:48 ` Dave Young [this message]
2011-11-22 2:48 ` Dave Young
2011-11-22 16:19 ` Tejun Heo
2011-11-22 16:19 ` Tejun Heo
2011-11-15 14:13 ` Crash during vmcore_init Américo Wang
2011-11-15 22:57 ` Tim Hartrick
2011-11-16 12:47 ` Américo Wang
2011-11-16 13:19 ` Tim Hartrick
2011-11-16 13:31 ` Américo Wang
2011-11-16 13:44 ` Tim Hartrick
[not found] ` <1321462343.4198.29.camel@boudreau>
2011-11-17 6:48 ` Américo Wang
2011-11-17 16:08 ` Tim Hartrick
2011-11-17 16:31 ` Tim Hartrick
2011-11-16 15:52 ` Tim Hartrick
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