Commit 0cbcc929 authored by Miaohe Lin's avatar Miaohe Lin Committed by Linus Torvalds
Browse files

kernel/resource: fix kfree() of bootmem memory again 

Since commit ebff7d8f ("mem hotunplug: fix kfree() of bootmem
memory"), we could get a resource allocated during boot via
alloc_resource().  And it's required to release the resource using
free_resource().  Howerver, many people use kfree directly which will
result in kernel BUG.  In order to fix this without fixing every call
site, just leak a couple of bytes in such corner case.

Link: https://lkml.kernel.org/r/20220217083619.19305-1-linmiaohe@huawei.com


Fixes: ebff7d8f ("mem hotunplug: fix kfree() of bootmem memory")
Signed-off-by: default avatarMiaohe Lin <linmiaohe@huawei.com>
Suggested-by: default avatarDavid Hildenbrand <david@redhat.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Alistair Popple <apopple@nvidia.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent b3d7fe86

kernel/resource.c

+8 −33
Original line number Diff line number Diff line
@@ -56,14 +56,6 @@ struct resource_constraint { 


static DEFINE_RWLOCK(resource_lock);



/*

 * For memory hotplug, there is no way to free resource entries allocated

 * by boot mem after the system is up. So for reusing the resource entry

 * we need to remember the resource.

 */

static struct resource *bootmem_resource_free;

static DEFINE_SPINLOCK(bootmem_resource_lock);



static struct resource *next_resource(struct resource *p)

{

	if (p->child)
@@ -160,36 +152,19 @@ __initcall(ioresources_init); 


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_free;

		bootmem_resource_free = res;

		spin_unlock(&bootmem_resource_lock);

	} else {

	/**

	 * If the resource was allocated using memblock early during boot

	 * we'll leak it here: we can only return full pages back to the

	 * buddy and trying to be smart and reusing them eventually in

	 * alloc_resource() overcomplicates resource handling.

	 */

	if (res && PageSlab(virt_to_head_page(res)))

		kfree(res);

}

}



static struct resource *alloc_resource(gfp_t flags)

{

	struct resource *res = NULL;



	spin_lock(&bootmem_resource_lock);

	if (bootmem_resource_free) {

		res = bootmem_resource_free;

		bootmem_resource_free = res->sibling;

	}

	spin_unlock(&bootmem_resource_lock);



	if (res)

		memset(res, 0, sizeof(struct resource));

	else

		res = kzalloc(sizeof(struct resource), flags);



	return res;

	return kzalloc(sizeof(struct resource), flags);

}



/* Return the conflict entry if you can't request it */