From 0212babb656495755ad4bfeb1066aa5c83efd2fd Mon Sep 17 00:00:00 2001 From: Pasha Tatashin Date: Wed, 12 Apr 2023 19:59:39 +0000 Subject: [PATCH] mm: hugetlb_vmemmap: provide stronger vmemmap allocation guarantees HugeTLB pages have a struct page optimizations where struct pages for tail pages are freed. However, when HugeTLB pages are destroyed, the memory for struct pages (vmemmap) needs to be allocated again. Currently, __GFP_NORETRY flag is used to allocate the memory for vmemmap, but given that this flag makes very little effort to actually reclaim memory the returning of huge pages back to the system can be problem. Lets use __GFP_RETRY_MAYFAIL instead. This flag is also performs graceful reclaim without causing ooms, but at least it may perform a few retries, and will fail only when there is genuinely little amount of unused memory in the system. Link: https://lkml.kernel.org/r/20230412195939.1242462-1-pasha.tatashin@soleen.com Signed-off-by: Pasha Tatashin Suggested-by: David Rientjes Cc: Michal Hocko Cc: Mike Kravetz Cc: Muchun Song Signed-off-by: Andrew Morton --- mm/hugetlb_vmemmap.c | 11 +++++------ 1 file changed, 5 insertions(+), 6 deletions(-) diff --git a/mm/hugetlb_vmemmap.c b/mm/hugetlb_vmemmap.c index 27f001e0f0a2..f42079b73f82 100644 --- a/mm/hugetlb_vmemmap.c +++ b/mm/hugetlb_vmemmap.c @@ -384,8 +384,9 @@ static int vmemmap_remap_free(unsigned long start, unsigned long end, } static int alloc_vmemmap_page_list(unsigned long start, unsigned long end, - gfp_t gfp_mask, struct list_head *list) + struct list_head *list) { + gfp_t gfp_mask = GFP_KERNEL | __GFP_RETRY_MAYFAIL | __GFP_THISNODE; unsigned long nr_pages = (end - start) >> PAGE_SHIFT; int nid = page_to_nid((struct page *)start); struct page *page, *next; @@ -413,12 +414,11 @@ out: * @end: end address of the vmemmap virtual address range that we want to * remap. * @reuse: reuse address. - * @gfp_mask: GFP flag for allocating vmemmap pages. * * Return: %0 on success, negative error code otherwise. */ static int vmemmap_remap_alloc(unsigned long start, unsigned long end, - unsigned long reuse, gfp_t gfp_mask) + unsigned long reuse) { LIST_HEAD(vmemmap_pages); struct vmemmap_remap_walk walk = { @@ -430,7 +430,7 @@ static int vmemmap_remap_alloc(unsigned long start, unsigned long end, /* See the comment in the vmemmap_remap_free(). */ BUG_ON(start - reuse != PAGE_SIZE); - if (alloc_vmemmap_page_list(start, end, gfp_mask, &vmemmap_pages)) + if (alloc_vmemmap_page_list(start, end, &vmemmap_pages)) return -ENOMEM; mmap_read_lock(&init_mm); @@ -476,8 +476,7 @@ int hugetlb_vmemmap_restore(const struct hstate *h, struct page *head) * When a HugeTLB page is freed to the buddy allocator, previously * discarded vmemmap pages must be allocated and remapping. */ - ret = vmemmap_remap_alloc(vmemmap_start, vmemmap_end, vmemmap_reuse, - GFP_KERNEL | __GFP_NORETRY | __GFP_THISNODE); + ret = vmemmap_remap_alloc(vmemmap_start, vmemmap_end, vmemmap_reuse); if (!ret) { ClearHPageVmemmapOptimized(head); static_branch_dec(&hugetlb_optimize_vmemmap_key); -- 2.50.1