2016-03-15 13:10 GMT+03:00 Alexander Potapenko <glider@xxxxxxxxxx>:
>
> static inline int kasan_module_alloc(void *addr, size_t size) { return 0; }
> static inline void kasan_free_shadow(const struct vm_struct *vm) {}
> diff --git a/lib/test_kasan.c b/lib/test_kasan.c
> index 82169fb..799c98e 100644
> --- a/lib/test_kasan.c
> +++ b/lib/test_kasan.c
> @@ -344,6 +344,32 @@ static noinline void __init kasan_stack_oob(void)
> *(volatile char *)p;
> }
>
> +#ifdef CONFIG_SLAB
> +static noinline void __init kasan_quarantine_cache(void)
> +{
> + struct kmem_cache *cache = kmem_cache_create(
> + "test", 137, 8, GFP_KERNEL, NULL);
> + int i;
> +
> + for (i = 0; i < 100; i++) {
> + void *p = kmem_cache_alloc(cache, GFP_KERNEL);
> +
> + kmem_cache_free(cache, p);
> + p = kmalloc(sizeof(u64), GFP_KERNEL);
> + kfree(p);
> + }
> + kmem_cache_shrink(cache);
> + for (i = 0; i < 100; i++) {
> + u64 *p = kmem_cache_alloc(cache, GFP_KERNEL);
> +
> + kmem_cache_free(cache, p);
> + p = kmalloc(sizeof(u64), GFP_KERNEL);
> + kfree(p);
> + }
> + kmem_cache_destroy(cache);
> +}
> +#endif
> +
Test looks quite useless. The kernel does allocations/frees all the
time, so I don't think that this test
adds something valuable.
And what's the result that we expect from this test? No crashes?
I'm thinking it would better to remove it.
[...]
> +
> +/* smp_load_acquire() here pairs with smp_store_release() in
> + * quarantine_reduce().
> + */
> +#define QUARANTINE_LOW_SIZE (smp_load_acquire(&quarantine_size) * 3 / 4)
I'd prefer open coding barrier with a proper comment int place,
instead of sneaking it into macros.
[...]
> +
> +void quarantine_reduce(void)
> +{
> + size_t new_quarantine_size;
> + unsigned long flags;
> + struct qlist to_free = QLIST_INIT;
> + size_t size_to_free = 0;
> + void **last;
> +
> + /* smp_load_acquire() here pairs with smp_store_release() below. */
Besides pairing rules, the comment should also explain *why* we need
this and for what
load/stores it provides memory ordering guarantees. For example take a
look at other
comments near barriers in the kernel tree.
> + if (likely(ACCESS_ONCE(global_quarantine.bytes) <=
> + smp_load_acquire(&quarantine_size)))
> + return;
> +
>
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