From 3cde287bb4769fe9dfc9c532ddc88d90e81bc4c5 Mon Sep 17 00:00:00 2001 From: Yu Zhao Date: Wed, 4 Dec 2019 16:49:56 -0800 Subject: [PATCH] mm/memory.c: replace is_zero_pfn with is_huge_zero_pmd for thp For hugely mapped thp, we use is_huge_zero_pmd() to check if it's zero page or not. We do fill ptes with my_zero_pfn() when we split zero thp pmd, but this is not what we have in vm_normal_page_pmd() -- pmd_trans_huge_lock() makes sure of it. This is a trivial fix for /proc/pid/numa_maps, and AFAIK nobody complains about it. Gerald Schaefer asked: : Maybe the description could also mention the symptom of this bug? : I would assume that it affects anon/dirty accounting in gather_pte_stats(), : for huge mappings, if zero page mappings are not correctly recognized. I came across this while I was looking at the code, so I'm not aware of any symptom. Link: http://lkml.kernel.org/r/20191108192629.201556-1-yuzhao@google.com Signed-off-by: Yu Zhao Acked-by: Andrew Morton Cc: Matthew Wilcox Cc: Ralph Campbell Cc: Will Deacon Cc: Peter Zijlstra Cc: "Aneesh Kumar K . V" Cc: Dave Airlie Cc: Thomas Hellstrom Cc: Souptick Joarder Cc: Gerald Schaefer Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/memory.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/memory.c b/mm/memory.c index 513c3ecc76ee..e455160e0f75 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -672,7 +672,7 @@ struct page *vm_normal_page_pmd(struct vm_area_struct *vma, unsigned long addr, if (pmd_devmap(pmd)) return NULL; - if (is_zero_pfn(pfn)) + if (is_huge_zero_pmd(pmd)) return NULL; if (unlikely(pfn > highest_memmap_pfn)) return NULL;