From: Bibo Mao maobibo@loongson.cn
stable inclusion from linux-4.19.198 commit 909bfdecf39843d1e42a9480a9c3ed49f7579707
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[ Upstream commit 33ae8f801ad8bec48e886d368739feb2816478f2 ]
If multiple threads are accessing the same huge page at the same time, hugetlb_cow will be called if one thread write the COW huge page. And function huge_ptep_clear_flush is called to notify other threads to clear the huge pte tlb entry. The other threads clear the huge pte tlb entry and reload it from page table, the reload huge pte entry may be old.
This patch fixes this issue on mips platform, and it clears huge pte entry before notifying other threads to flush current huge page entry, it is similar with other architectures.
Signed-off-by: Bibo Mao maobibo@loongson.cn Signed-off-by: Thomas Bogendoerfer tsbogend@alpha.franken.de Signed-off-by: Sasha Levin sashal@kernel.org Signed-off-by: Yang Yingliang yangyingliang@huawei.com --- arch/mips/include/asm/hugetlb.h | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/arch/mips/include/asm/hugetlb.h b/arch/mips/include/asm/hugetlb.h index 982bc06853302..4747a46946699 100644 --- a/arch/mips/include/asm/hugetlb.h +++ b/arch/mips/include/asm/hugetlb.h @@ -67,7 +67,13 @@ static inline pte_t huge_ptep_get_and_clear(struct mm_struct *mm, static inline void huge_ptep_clear_flush(struct vm_area_struct *vma, unsigned long addr, pte_t *ptep) { - flush_tlb_page(vma, addr & huge_page_mask(hstate_vma(vma))); + /* + * clear the huge pte entry firstly, so that the other smp threads will + * not get old pte entry after finishing flush_tlb_page and before + * setting new huge pte entry + */ + huge_ptep_get_and_clear(vma->vm_mm, addr, ptep); + flush_tlb_page(vma, addr); }
static inline int huge_pte_none(pte_t pte)