From: Christian Borntraeger Date: Sun, 9 Apr 2017 20:09:38 +0000 (+0200) Subject: s390/mm: fix CMMA vs KSM vs others X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=a8f60d1fadf7b8b54449fcc9d6b15248917478ba;p=GitHub%2Fmoto-9609%2Fandroid_kernel_motorola_exynos9610.git s390/mm: fix CMMA vs KSM vs others On heavy paging with KSM I see guest data corruption. Turns out that KSM will add pages to its tree, where the mapping return true for pte_unused (or might become as such later). KSM will unmap such pages and reinstantiate with different attributes (e.g. write protected or special, e.g. in replace_page or write_protect_page)). This uncovered a bug in our pagetable handling: We must remove the unused flag as soon as an entry becomes present again. Cc: stable@vger.kernel.org Signed-of-by: Christian Borntraeger Signed-off-by: Martin Schwidefsky --- diff --git a/arch/s390/include/asm/pgtable.h b/arch/s390/include/asm/pgtable.h index 93e37b12e882..ecec682bb516 100644 --- a/arch/s390/include/asm/pgtable.h +++ b/arch/s390/include/asm/pgtable.h @@ -1051,6 +1051,8 @@ static inline void set_pte_at(struct mm_struct *mm, unsigned long addr, { if (!MACHINE_HAS_NX) pte_val(entry) &= ~_PAGE_NOEXEC; + if (pte_present(entry)) + pte_val(entry) &= ~_PAGE_UNUSED; if (mm_has_pgste(mm)) ptep_set_pte_at(mm, addr, ptep, entry); else