From: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
To: Michael Ellerman <mpe@ellerman.id.au>
Cc: benh@kernel.crashing.org, paulus@samba.org,
linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH] powerpc/mm: Recompute hash value after a failed update
Date: Wed, 16 Sep 2015 11:27:54 +0530 [thread overview]
Message-ID: <87r3lyewil.fsf@linux.vnet.ibm.com> (raw)
In-Reply-To: <1442378949.21531.1.camel@ellerman.id.au>
Michael Ellerman <mpe@ellerman.id.au> writes:
> On Wed, 2015-09-16 at 08:53 +0530, Aneesh Kumar K.V wrote:
>> "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> writes:
>>
>> > If we had secondary hash flag set, we ended up modifying hash value in
>> > the updatepp code path. Hence with a failed updatepp we will be using
>> > a wrong hash value for the following hash insert. Fix this by
>> > recomputing hash before insert.
>>
>> Without this patch we can end up with using wrong slot number in linux
>> pte. That can result in us missing an hash pte update or invalidate
>> which can cause memory corruption or even machine check ?
>
> Thanks. When did this break? Always? If so this should go to stable?
>
IIUC we have this issue with initial support for THP (6d492ecc6489113968ec269be1cf88942d4a5d29)
" powerpc/THP: Add code to handle HPTE faults for hugepages". So yes
this should got to stable.
-aneesh
next prev parent reply other threads:[~2015-09-16 5:58 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-09-15 7:00 [PATCH] powerpc/mm: Recompute hash value after a failed update Aneesh Kumar K.V
2015-09-16 3:23 ` Aneesh Kumar K.V
2015-09-16 4:49 ` Michael Ellerman
2015-09-16 5:57 ` Aneesh Kumar K.V [this message]
2015-09-16 7:27 ` Michael Ellerman
2015-09-16 18:59 ` Aneesh Kumar K.V
2015-09-16 4:56 ` Paul Mackerras
2015-09-17 5:13 ` Michael Ellerman
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