From: Miaohe Lin linmiaohe@huawei.com

[ Upstream commit 0cbcc92917c5de80f15c24d033566539ad696892 ]

Since commit ebff7d8f270d ("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: ebff7d8f270d ("mem hotunplug: fix kfree() of bootmem memory") Signed-off-by: Miaohe Lin linmiaohe@huawei.com Suggested-by: David Hildenbrand david@redhat.com Cc: Dan Williams dan.j.williams@intel.com Cc: Alistair Popple apopple@nvidia.com Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Sasha Levin sashal@kernel.org Signed-off-by: David Sauerwein dssauerw@amazon.de --- kernel/resource.c | 41 ++++++++--------------------------------- 1 file changed, 8 insertions(+), 33 deletions(-)

diff --git a/kernel/resource.c b/kernel/resource.c index 1087f33d70c4..ea4d7a02b8e8 100644 --- a/kernel/resource.c +++ b/kernel/resource.c @@ -53,14 +53,6 @@ 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, bool sibling_only) { /* Caller wants to traverse through siblings only */ @@ -149,36 +141,19 @@ __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 */