On 2016/7/20 17:19, Catalin Marinas wrote: > On Wed, Jul 20, 2016 at 10:46:27AM +0800, Leizhen (ThunderTown) wrote: >>>>>> On 2016/7/8 21:54, Catalin Marinas wrote: >>>>>>> ------------8<---------------- >>>>>>> diff --git a/arch/arm64/mm/flush.c b/arch/arm64/mm/flush.c >>>>>>> index dbd12ea8ce68..c753fa804165 100644 >>>>>>> --- a/arch/arm64/mm/flush.c >>>>>>> +++ b/arch/arm64/mm/flush.c >>>>>>> @@ -75,7 +75,8 @@ void __sync_icache_dcache(pte_t pte, unsigned long >>>>>>> addr) >>>>>>> if (!page_mapping(page)) >>>>>>> return; >>>>>>> >>>>>>> - if (!test_and_set_bit(PG_dcache_clean, &page->flags)) >>>>>>> + if (!test_and_set_bit(PG_dcache_clean, &page->flags) || >>>>>>> + PageDirty(page)) >>>>>>> sync_icache_aliases(page_address(page), >>>>>>> PAGE_SIZE << compound_order(page)); >>>>>>> else if (icache_is_aivivt()) >>>>>>> ----------------8<--------------------- >> >> Do you plan to send this patch? My colleagues told me that if our >> patches are quite different, it should be Signed-off-by you. > > The reason I'm not sending it is that I don't fully understand how it > solves the problem for a shared file mmap(), not just hugetlbfs. As I > said in an earlier email: after an msync() in user space we > should flush the pages to disk via write_cache_pages(). This function Hi Catalin: I'm so sorry for my fault. The previous small pages test result I actually ran on ramfs. Today, I ran the case on harddisk fs, it worked well without this patch.
Summarized as follows: small pages on ramfs: need this patch small pages on harddisk fs: no need this patch hugetlbfs: need this patch > calls clear_page_dirty_for_io() after which PageDirty() is no longer > true. I can't tell how a subsequent mmap() can see the written pages as > dirty. > >> I searched all Linux source code, __sync_icache_dcache is only called >> by set_pte_at, and some check conditions(especially pte_exec) will >> limit its impact. >> >> if (pte_user(pte) && pte_exec(pte) && !pte_special(pte)) >> __sync_icache_dcache(pte, addr); > > Yes, and set_pte_at() would be called as a result of a page fault when > accessing the mmap'ed file. >
