2004-01-25 14:00:42

by walter harms

Subject: mm/slab.c: linux 2.6.1 fix 2 unguarded kmalloc and a PAGE_SHIFT

Hi list,
this fixes catches 2 unguarded kmallocs() and changes a statement so that PAGE_SHIFT >20 causes a warning.
At least sparc64 is prepared for a PAGE_SHIFT >20.

hope that helps,
walter


--- mm/slab.c.org 2004-01-25 08:18:25.243165360 +0100
+++ mm/slab.c 2004-01-25 08:33:05.135401408 +0100
@@ -666,7 +666,7 @@
* Fragmentation resistance on low memory - only use bigger
* page orders on machines with more than 32MB of memory.
*/
- if (num_physpages > (32 << 20) >> PAGE_SHIFT)
+ if (num_physpages > (32 << (20-PAGE_SHIFT) )
slab_break_gfp_order = BREAK_GFP_ORDER_HI;


@@ -737,6 +737,10 @@
void * ptr;

ptr = kmalloc(sizeof(struct arraycache_init), GFP_KERNEL);
+
+ if (!ptr)
+ BUG();
+
local_irq_disable();
BUG_ON(ac_data(&cache_cache) != &initarray_cache.cache);
memcpy(ptr, ac_data(&cache_cache), sizeof(struct arraycache_init
));
@@ -744,6 +748,10 @@
local_irq_enable();

ptr = kmalloc(sizeof(struct arraycache_init), GFP_KERNEL);
+
+ if (!ptr)
+ BUG();
+
local_irq_disable();
BUG_ON(ac_data(malloc_sizes[0].cs_cachep) != &initarray_generic.
cache);
memcpy(ptr, ac_data(malloc_sizes[0].cs_cachep),

2004-01-25 18:16:31

by Manfred Spraul

Subject: Re: mm/slab.c: linux 2.6.1 fix 2 unguarded kmalloc and a PAGE_SHIFT

Hi Walter,

>this fixes catches 2 unguarded kmallocs() and changes a statement so that PAGE_SHIFT \
>>20 causes a warning. At least sparc64 is prepared for a PAGE_SHIFT >20.
>
>
Why should a page shift above 20 generate a warning?

The two unguarded kmallocs are obivously wrong, but I'd prefer to guard
them with __GFP_NOFAIL.

--
Manfred

2004-01-25 18:10:10

by Brian Gerst

Subject: Re: mm/slab.c: linux 2.6.1 fix 2 unguarded kmalloc and a PAGE_SHIFT

(Walter Harms) wrote:
> Hi list,
> this fixes catches 2 unguarded kmallocs() and changes a statement so that PAGE_SHIFT >20 causes a warning.
> At least sparc64 is prepared for a PAGE_SHIFT >20.
>
> hope that helps,
> walter
>
>
> --- mm/slab.c.org 2004-01-25 08:18:25.243165360 +0100
> +++ mm/slab.c 2004-01-25 08:33:05.135401408 +0100
> @@ -666,7 +666,7 @@
> * Fragmentation resistance on low memory - only use bigger
> * page orders on machines with more than 32MB of memory.
> */
> - if (num_physpages > (32 << 20) >> PAGE_SHIFT)
> + if (num_physpages > (32 << (20-PAGE_SHIFT) )
> slab_break_gfp_order = BREAK_GFP_ORDER_HI;
>
>
> @@ -737,6 +737,10 @@
> void * ptr;
>
> ptr = kmalloc(sizeof(struct arraycache_init), GFP_KERNEL);
> +
> + if (!ptr)
> + BUG();
> +
> local_irq_disable();
> BUG_ON(ac_data(&cache_cache) != &initarray_cache.cache);
> memcpy(ptr, ac_data(&cache_cache), sizeof(struct arraycache_init
> ));
> @@ -744,6 +748,10 @@
> local_irq_enable();
>
> ptr = kmalloc(sizeof(struct arraycache_init), GFP_KERNEL);
> +
> + if (!ptr)
> + BUG();
> +
> local_irq_disable();
> BUG_ON(ac_data(malloc_sizes[0].cs_cachep) != &initarray_generic.
> cache);
> memcpy(ptr, ac_data(malloc_sizes[0].cs_cachep),
>
> -
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>

BUG_ON(!ptr) would be better.

--
Brian Gerst