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

From: Linus Torvalds
Date: Sun Oct 29 2006 - 20:20:24 EST




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

---
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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