Re: [Bug fix PATCH v4] Reusing a resource structure allocated bybootmem

From: Johannes Weiner
Date: Thu Apr 18 2013 - 09:42:40 EST


On Thu, Apr 18, 2013 at 05:36:12PM +0900, Yasuaki Ishimatsu wrote:
> @@ -151,6 +162,39 @@ __initcall(ioresources_init);
>
> #endif /* CONFIG_PROC_FS */
>
> +static void free_resource(struct resource *res)
> +{
> + if (!res)
> + return;
> +
> + if (PageSlab(virt_to_head_page(res))) {
> + spin_lock(&bootmem_resource_lock);
> + res->sibling = bootmem_resource.sibling;
> + bootmem_resource.sibling = res;
> + spin_unlock(&bootmem_resource_lock);
> + } else {
> + kfree(res);
> + }

The branch is mixed up, you are collecting slab objects in
bootmem_resource and kfreeing bootmem.

> +static struct resource *get_resource(gfp_t flags)
> +{
> + struct resource *res = NULL;
> +
> + spin_lock(&bootmem_resource_lock);
> + if (bootmem_resource.sibling) {
> + res = bootmem_resource.sibling;
> + bootmem_resource.sibling = res->sibling;
> + memset(res, 0, sizeof(struct resource));
> + }
> + spin_unlock(&bootmem_resource_lock);
> +
> + if (!res)
> + res = kzalloc(sizeof(struct resource), flags);
> +
> + return res;
> +}
> +
> /* Return the conflict entry if you can't request it */
> static struct resource * __request_resource(struct resource *root, struct resource *new)
> {
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