From: Michael Ellerman <mpe@ellerman.id.au>
To: Paul Mackerras <paulus@samba.org>
Cc: linuxppc-dev@ozlabs.org, linux-kernel@vger.kernel.org,
Pekka Enberg <penberg@kernel.org>,
linux-mm@kvack.org, David Rientjes <rientjes@google.com>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>,
Andrew Morton <akpm@linux-foundation.org>,
Christoph Lameter <cl@linux.com>
Subject: Re: [PATCH v2] slab: Fix nodeid bounds check for non-contiguous node IDs
Date: Mon, 01 Dec 2014 16:02:14 +1100 [thread overview]
Message-ID: <1417410134.16178.2.camel@concordia> (raw)
In-Reply-To: <20141201042844.GB11234@drongo>
On Mon, 2014-12-01 at 15:28 +1100, Paul Mackerras wrote:
> The bounds check for nodeid in ____cache_alloc_node gives false
> positives on machines where the node IDs are not contiguous, leading
> to a panic at boot time. For example, on a POWER8 machine the node
> IDs are typically 0, 1, 16 and 17. This means that num_online_nodes()
> returns 4, so when ____cache_alloc_node is called with nodeid = 16 the
> VM_BUG_ON triggers, like this:
...
>
> To fix this, we instead compare the nodeid with MAX_NUMNODES, and
> additionally make sure it isn't negative (since nodeid is an int).
> The check is there mainly to protect the array dereference in the
> get_node() call in the next line, and the array being dereferenced is
> of size MAX_NUMNODES. If the nodeid is in range but invalid (for
> example if the node is off-line), the BUG_ON in the next line will
> catch that.
When did this break? How come we only just noticed?
Also needs:
Cc: stable@vger.kernel.org
cheers
WARNING: multiple messages have this Message-ID (diff)
From: Michael Ellerman <mpe@ellerman.id.au>
To: Paul Mackerras <paulus@samba.org>
Cc: linux-mm@kvack.org, Andrew Morton <akpm@linux-foundation.org>,
linux-kernel@vger.kernel.org, Pekka Enberg <penberg@kernel.org>,
linuxppc-dev@ozlabs.org, David Rientjes <rientjes@google.com>,
Christoph Lameter <cl@linux.com>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>
Subject: Re: [PATCH v2] slab: Fix nodeid bounds check for non-contiguous node IDs
Date: Mon, 01 Dec 2014 16:02:14 +1100 [thread overview]
Message-ID: <1417410134.16178.2.camel@concordia> (raw)
In-Reply-To: <20141201042844.GB11234@drongo>
On Mon, 2014-12-01 at 15:28 +1100, Paul Mackerras wrote:
> The bounds check for nodeid in ____cache_alloc_node gives false
> positives on machines where the node IDs are not contiguous, leading
> to a panic at boot time. For example, on a POWER8 machine the node
> IDs are typically 0, 1, 16 and 17. This means that num_online_nodes()
> returns 4, so when ____cache_alloc_node is called with nodeid = 16 the
> VM_BUG_ON triggers, like this:
...
>
> To fix this, we instead compare the nodeid with MAX_NUMNODES, and
> additionally make sure it isn't negative (since nodeid is an int).
> The check is there mainly to protect the array dereference in the
> get_node() call in the next line, and the array being dereferenced is
> of size MAX_NUMNODES. If the nodeid is in range but invalid (for
> example if the node is off-line), the BUG_ON in the next line will
> catch that.
When did this break? How come we only just noticed?
Also needs:
Cc: stable@vger.kernel.org
cheers
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WARNING: multiple messages have this Message-ID (diff)
From: Michael Ellerman <mpe@ellerman.id.au>
To: Paul Mackerras <paulus@samba.org>
Cc: linux-mm@kvack.org, Andrew Morton <akpm@linux-foundation.org>,
linux-kernel@vger.kernel.org, Pekka Enberg <penberg@kernel.org>,
linuxppc-dev@ozlabs.org, David Rientjes <rientjes@google.com>,
Christoph Lameter <cl@linux.com>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>
Subject: Re: [PATCH v2] slab: Fix nodeid bounds check for non-contiguous node IDs
Date: Mon, 01 Dec 2014 16:02:14 +1100 [thread overview]
Message-ID: <1417410134.16178.2.camel@concordia> (raw)
In-Reply-To: <20141201042844.GB11234@drongo>
On Mon, 2014-12-01 at 15:28 +1100, Paul Mackerras wrote:
> The bounds check for nodeid in ____cache_alloc_node gives false
> positives on machines where the node IDs are not contiguous, leading
> to a panic at boot time. For example, on a POWER8 machine the node
> IDs are typically 0, 1, 16 and 17. This means that num_online_nodes()
> returns 4, so when ____cache_alloc_node is called with nodeid = 16 the
> VM_BUG_ON triggers, like this:
...
>
> To fix this, we instead compare the nodeid with MAX_NUMNODES, and
> additionally make sure it isn't negative (since nodeid is an int).
> The check is there mainly to protect the array dereference in the
> get_node() call in the next line, and the array being dereferenced is
> of size MAX_NUMNODES. If the nodeid is in range but invalid (for
> example if the node is off-line), the BUG_ON in the next line will
> catch that.
When did this break? How come we only just noticed?
Also needs:
Cc: stable@vger.kernel.org
cheers
next prev parent reply other threads:[~2014-12-01 5:02 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-12-01 4:28 [PATCH v2] slab: Fix nodeid bounds check for non-contiguous node IDs Paul Mackerras
2014-12-01 4:28 ` Paul Mackerras
2014-12-01 4:28 ` Paul Mackerras
2014-12-01 4:58 ` Yasuaki Ishimatsu
2014-12-01 4:58 ` Yasuaki Ishimatsu
2014-12-01 4:58 ` Yasuaki Ishimatsu
2014-12-01 5:02 ` Michael Ellerman [this message]
2014-12-01 5:02 ` Michael Ellerman
2014-12-01 5:02 ` Michael Ellerman
2014-12-01 5:24 ` Paul Mackerras
2014-12-01 5:24 ` Paul Mackerras
2014-12-01 5:24 ` Paul Mackerras
2014-12-01 8:52 ` Michael Ellerman
2014-12-01 8:52 ` Michael Ellerman
2014-12-01 8:52 ` Michael Ellerman
2014-12-01 9:22 ` Pekka Enberg
2014-12-01 9:22 ` Pekka Enberg
2014-12-01 9:22 ` Pekka Enberg
2014-12-01 21:06 ` David Rientjes
2014-12-01 21:06 ` David Rientjes
2014-12-01 21:06 ` David Rientjes
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