Re: Slab panic on 2.6.19-rc3-git5 (-git4 was OK)

From: Andy Whitcroft
Date: Mon Oct 30 2006 - 04:56:12 EST


Linus Torvalds wrote:
>
> On Sun, 29 Oct 2006, Martin J. Bligh wrote:
>> Seems like that doesn't fix it, I'm afraid.
>
> Does the one in the current -git tree? It's commit
> 5211e6e6c671f0d4b1e1a1023384d20227d8ee65, as below..
>
> Linus

Submitted that commit, results in a couple of hours.

-apw

>
> ---
> commit 5211e6e6c671f0d4b1e1a1023384d20227d8ee65
> Author: Giridhar Pemmasani <pgiri@xxxxxxxxx>
> Date: Sun Oct 29 04:46:55 2006 -0800
>
> [PATCH] Fix GFP_HIGHMEM slab panic
>
> As reported by Martin J. Bligh <mbligh@xxxxxxxxxx>, we let through some
> non-slab bits to slab allocation through __get_vm_area_node when doing a
> vmalloc.
>
> I haven't been able to reproduce this, although I understand why it
> happens: vmalloc allocates memory with
>
> GFP_KERNEL | __GFP_HIGHMEM
>
> and commit 52fd24ca1db3a741f144bbc229beefe044202cac resulted in the same
> flags are passed down to cache_alloc_refill, causing the BUG. The
> following patch fixes it.
>
> Note that when calling kmalloc_node, I am masking off __GFP_HIGHMEM with
> GFP_LEVEL_MASK, whereas __vmalloc_area_node does the same with
>
> ~(__GFP_HIGHMEM | __GFP_ZERO).
>
> IMHO, using GFP_LEVEL_MASK is preferable, but either should fix this
> problem.
>
> Signed-off-by: Giridhar Pemmasani (pgiri@xxxxxxxxx)
> Cc: Martin J. Bligh <mbligh@xxxxxxxxxx>
> Cc: Andrew Morton <akpm@xxxxxxxx>
> Signed-off-by: Linus Torvalds <torvalds@xxxxxxxx>
>
> diff --git a/mm/vmalloc.c b/mm/vmalloc.c
> index 6d381df..46606c1 100644
> --- a/mm/vmalloc.c
> +++ b/mm/vmalloc.c
> @@ -182,7 +182,7 @@ static struct vm_struct *__get_vm_area_n
> addr = ALIGN(start, align);
> size = PAGE_ALIGN(size);
>
> - area = kmalloc_node(sizeof(*area), gfp_mask, node);
> + area = kmalloc_node(sizeof(*area), gfp_mask & GFP_LEVEL_MASK, node);
> if (unlikely(!area))
> return NULL;
>

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