From a72a30af550c08423de1b9feecb6ceeddc434889 Mon Sep 17 00:00:00 2001 From: "Ho-Ren (Jack) Chuang" Date: Fri, 5 Apr 2024 00:07:05 +0000 Subject: memory tier: dax/kmem: introduce an abstract layer for finding, allocating, and putting memory types Patch series "Improved Memory Tier Creation for CPUless NUMA Nodes", v11. When a memory device, such as CXL1.1 type3 memory, is emulated as normal memory (E820_TYPE_RAM), the memory device is indistinguishable from normal DRAM in terms of memory tiering with the current implementation. The current memory tiering assigns all detected normal memory nodes to the same DRAM tier. This results in normal memory devices with different attributions being unable to be assigned to the correct memory tier, leading to the inability to migrate pages between different types of memory. https://lore.kernel.org/linux-mm/PH0PR08MB7955E9F08CCB64F23963B5C3A860A@PH0PR08MB7955.namprd08.prod.outlook.com/T/ This patchset automatically resolves the issues. It delays the initialization of memory tiers for CPUless NUMA nodes until they obtain HMAT information and after all devices are initialized at boot time, eliminating the need for user intervention. If no HMAT is specified, it falls back to using `default_dram_type`. Example usecase: We have CXL memory on the host, and we create VMs with a new system memory device backed by host CXL memory. We inject CXL memory performance attributes through QEMU, and the guest now sees memory nodes with performance attributes in HMAT. With this change, we enable the guest kernel to construct the correct memory tiering for the memory nodes. This patch (of 2): Since different memory devices require finding, allocating, and putting memory types, these common steps are abstracted in this patch, enhancing the scalability and conciseness of the code. Link: https://lkml.kernel.org/r/20240405000707.2670063-1-horenchuang@bytedance.com Link: https://lkml.kernel.org/r/20240405000707.2670063-2-horenchuang@bytedance.com Signed-off-by: Ho-Ren (Jack) Chuang Reviewed-by: "Huang, Ying" Reviewed-by: Jonathan Cameron Cc: Alistair Popple Cc: Aneesh Kumar K.V Cc: Dan Williams Cc: Dave Jiang Cc: Gregory Price Cc: Hao Xiang Cc: Jonathan Cameron Cc: Michal Hocko Cc: Ravi Jonnalagadda Cc: SeongJae Park Cc: Tejun Heo Cc: Vishal Verma Signed-off-by: Andrew Morton --- drivers/dax/kmem.c | 30 ++++-------------------------- 1 file changed, 4 insertions(+), 26 deletions(-) (limited to 'drivers/dax/kmem.c') diff --git a/drivers/dax/kmem.c b/drivers/dax/kmem.c index 42ee360cf4e3..4fe9d040e375 100644 --- a/drivers/dax/kmem.c +++ b/drivers/dax/kmem.c @@ -55,36 +55,14 @@ static LIST_HEAD(kmem_memory_types); static struct memory_dev_type *kmem_find_alloc_memory_type(int adist) { - bool found = false; - struct memory_dev_type *mtype; - - mutex_lock(&kmem_memory_type_lock); - list_for_each_entry(mtype, &kmem_memory_types, list) { - if (mtype->adistance == adist) { - found = true; - break; - } - } - if (!found) { - mtype = alloc_memory_type(adist); - if (!IS_ERR(mtype)) - list_add(&mtype->list, &kmem_memory_types); - } - mutex_unlock(&kmem_memory_type_lock); - - return mtype; + guard(mutex)(&kmem_memory_type_lock); + return mt_find_alloc_memory_type(adist, &kmem_memory_types); } static void kmem_put_memory_types(void) { - struct memory_dev_type *mtype, *mtn; - - mutex_lock(&kmem_memory_type_lock); - list_for_each_entry_safe(mtype, mtn, &kmem_memory_types, list) { - list_del(&mtype->list); - put_memory_type(mtype); - } - mutex_unlock(&kmem_memory_type_lock); + guard(mutex)(&kmem_memory_type_lock); + mt_put_memory_types(&kmem_memory_types); } static int dev_dax_kmem_probe(struct dev_dax *dev_dax) -- cgit v1.2.3