From af5b0f6a09e42c9f4fa87735f2a366748767b686 Mon Sep 17 00:00:00 2001 From: Kirill A. Shutemov Date: Wed, 15 Nov 2017 17:35:40 -0800 Subject: mm: consolidate page table accounting Currently, we account page tables separately for each page table level, but that's redundant -- we only make use of total memory allocated to page tables for oom_badness calculation. We also provide the information to userspace, but it has dubious value there too. This patch switches page table accounting to single counter. mm->pgtables_bytes is now used to account all page table levels. We use bytes, because page table size for different levels of page table tree may be different. The change has user-visible effect: we don't have VmPMD and VmPUD reported in /proc/[pid]/status. Not sure if anybody uses them. (As alternative, we can always report 0 kB for them.) OOM-killer report is also slightly changed: we now report pgtables_bytes instead of nr_ptes, nr_pmd, nr_puds. Apart from reducing number of counters per-mm, the benefit is that we now calculate oom_badness() more correctly for machines which have different size of page tables depending on level or where page tables are less than a page in size. The only downside can be debuggability because we do not know which page table level could leak. But I do not remember many bugs that would be caught by separate counters so I wouldn't lose sleep over this. [akpm@linux-foundation.org: fix mm/huge_memory.c] Link: http://lkml.kernel.org/r/20171006100651.44742-2-kirill.shutemov@linux.intel.com Signed-off-by: Kirill A. Shutemov Acked-by: Michal Hocko [kirill.shutemov@linux.intel.com: fix build] Link: http://lkml.kernel.org/r/20171016150113.ikfxy3e7zzfvsr4w@black.fi.intel.com Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/huge_memory.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'mm/huge_memory.c') diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 3610d81c062a..86fe697e8bfb 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -942,7 +942,7 @@ int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm, set_pmd_at(src_mm, addr, src_pmd, pmd); } add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR); - atomic_long_inc(&dst_mm->nr_ptes); + mm_inc_nr_ptes(dst_mm); pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable); set_pmd_at(dst_mm, addr, dst_pmd, pmd); ret = 0; -- cgit v1.2.3-55-g7522