From mboxrd@z Thu Jan 1 00:00:00 1970 From: thunder.leizhen@huawei.com (Zhen Lei) Date: Thu, 7 Jul 2016 20:09:04 +0800 Subject: [PATCH 1/1] arm64/hugetlb: clear PG_dcache_clean if the page is dirty when munmap Message-ID: <1467893344-8352-1-git-send-email-thunder.leizhen@huawei.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org At present, PG_dcache_clean is only cleared when the related huge page is about to be freed. But sometimes, there maybe a process is in charge to copy binary codes into a shared memory, and notifies other processes to execute base on that. For the first time, there is no problem, because the default value of page->flags is PG_dcache_clean cleared. So the cache will be maintained at the time of set_pte_at for other processes. But if the content of the shared memory have been updated again, there is no cache operations, because the PG_dcache_clean is still set. For example: Process A open a hugetlbfs file mmap it as a shared memory copy some binary codes into it munmap Process B open the hugetlbfs file mmap it as a shared memory, executable invoke the functions in the shared memory munmap repeat the above steps. Signed-off-by: Zhen Lei --- arch/arm64/mm/hugetlbpage.c | 20 +++++++++++++++----- 1 file changed, 15 insertions(+), 5 deletions(-) diff --git a/arch/arm64/mm/hugetlbpage.c b/arch/arm64/mm/hugetlbpage.c index 2e49bd2..547b158 100644 --- a/arch/arm64/mm/hugetlbpage.c +++ b/arch/arm64/mm/hugetlbpage.c @@ -201,6 +201,7 @@ pte_t huge_ptep_get_and_clear(struct mm_struct *mm, unsigned long addr, pte_t *ptep) { pte_t pte; + struct page *page; if (pte_cont(*ptep)) { int ncontig, i; @@ -222,12 +223,21 @@ pte_t huge_ptep_get_and_clear(struct mm_struct *mm, if (pte_dirty(ptep_get_and_clear(mm, addr, cpte))) is_dirty = true; } - if (is_dirty) - return pte_mkdirty(pte); - else - return pte; + if (is_dirty) { + pte = pte_mkdirty(pte); + page = pte_page(pte); + clear_bit(PG_dcache_clean, &page->flags); + } + + return pte; } else { - return ptep_get_and_clear(mm, addr, ptep); + pte = ptep_get_and_clear(mm, addr, ptep); + if (huge_pte_dirty(pte)) { + page = pte_page(pte); + clear_bit(PG_dcache_clean, &page->flags); + } + + return pte; } } -- 2.5.0