2013-04-23 14:31:43

by Aaron Tomlin

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Subject: [Patch v2] mm: slab: Verify the nodeid passed to ____cache_alloc_node

Hi,

This patch is in response to BZ#42967 [1].
Using VM_BUG_ON so it's used only when CONFIG_DEBUG_VM is set,
given that ____cache_alloc_node() is a hot code path.

Cheers,
Aaron

[1]: https://bugzilla.kernel.org/show_bug.cgi?id=42967

---8<---
mm: slab: Verify the nodeid passed to ____cache_alloc_node

If the nodeid is > num_online_nodes() this can cause an
Oops and a panic(). The purpose of this patch is to assert
if this condition is true to aid debugging efforts rather
than some random NULL pointer dereference or page fault.

Signed-off-by: Aaron Tomlin <[email protected]>
Reviewed-by: Rik van Riel <[email protected]>


slab.c | 1 +
1 file changed, 1 insertion(+)

diff --git a/mm/slab.c b/mm/slab.c
index e7667a3..735e8bd 100644
--- a/mm/slab.c
+++ b/mm/slab.c
-3412,6 +3412,7 @@ static void *____cache_alloc_node(struct kmem_cache *cachep, gfp_t flags,
void *obj;
int x;

+ VM_BUG_ON(nodeid > num_online_nodes());
l3 = cachep->nodelists[nodeid];
BUG_ON(!l3);


2013-04-23 15:58:39

by Christopher Lameter

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Subject: Re: [Patch v2] mm: slab: Verify the nodeid passed to ____cache_alloc_node

On Tue, 23 Apr 2013, Aaron Tomlin wrote:

> This patch is in response to BZ#42967 [1].
> Using VM_BUG_ON so it's used only when CONFIG_DEBUG_VM is set,
> given that ____cache_alloc_node() is a hot code path.

Acked-by: Christoph Lameter <[email protected]>

2013-04-23 16:45:40

by Rafael Aquini

[permalink] [raw]
Subject: Re: [Patch v2] mm: slab: Verify the nodeid passed to ____cache_alloc_node

On Tue, Apr 23, 2013 at 10:31:36AM -0400, Aaron Tomlin wrote:
> Hi,
>
> This patch is in response to BZ#42967 [1].
> Using VM_BUG_ON so it's used only when CONFIG_DEBUG_VM is set,
> given that ____cache_alloc_node() is a hot code path.
>
This seems to be a valid condition to BUG_ON, though.

> Cheers,
> Aaron
>
> [1]: https://bugzilla.kernel.org/show_bug.cgi?id=42967
>
> ---8<---
> mm: slab: Verify the nodeid passed to ____cache_alloc_node
>
> If the nodeid is > num_online_nodes() this can cause an
> Oops and a panic(). The purpose of this patch is to assert
> if this condition is true to aid debugging efforts rather
> than some random NULL pointer dereference or page fault.
>
> Signed-off-by: Aaron Tomlin <[email protected]>
> Reviewed-by: Rik van Riel <[email protected]>
>

Acked-by: Rafael Aquini <[email protected]>



>
> slab.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/mm/slab.c b/mm/slab.c
> index e7667a3..735e8bd 100644
> --- a/mm/slab.c
> +++ b/mm/slab.c
> -3412,6 +3412,7 @@ static void *____cache_alloc_node(struct kmem_cache *cachep, gfp_t flags,
> void *obj;
> int x;
>
> + VM_BUG_ON(nodeid > num_online_nodes());
> l3 = cachep->nodelists[nodeid];
> BUG_ON(!l3);

2013-04-23 23:16:48

by David Rientjes

[permalink] [raw]
Subject: Re: [Patch v2] mm: slab: Verify the nodeid passed to ____cache_alloc_node

On Tue, 23 Apr 2013, Aaron Tomlin wrote:

> mm: slab: Verify the nodeid passed to ____cache_alloc_node
>
> If the nodeid is > num_online_nodes() this can cause an
> Oops and a panic(). The purpose of this patch is to assert
> if this condition is true to aid debugging efforts rather
> than some random NULL pointer dereference or page fault.
>
> Signed-off-by: Aaron Tomlin <[email protected]>
> Reviewed-by: Rik van Riel <[email protected]>
>

Acked-by: David Rientjes <[email protected]>

2013-04-24 07:26:27

by Pekka Enberg

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Subject: Re: [Patch v2] mm: slab: Verify the nodeid passed to ____cache_alloc_node

On Tue, Apr 23, 2013 at 5:31 PM, Aaron Tomlin <[email protected]> wrote:
> This patch is in response to BZ#42967 [1].
> Using VM_BUG_ON so it's used only when CONFIG_DEBUG_VM is set,
> given that ____cache_alloc_node() is a hot code path.

The patch is pretty badly mangled and does not apply with 'git am'.
Please resend with updated ACKs.

Pekka