Messages in this thread Patch in this message | | | From | Zhen Lei <> | Subject | [PATCH 1/1] arm64/hugetlb: clear PG_dcache_clean if the page is dirty when munmap | Date | Thu, 7 Jul 2016 20:09:04 +0800 |
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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 <thunder.leizhen@huawei.com> --- 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
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