On 2016/8/24 1:28, Catalin Marinas wrote: > On Mon, Aug 22, 2016 at 12:19:04PM +0800, Leizhen (ThunderTown) wrote: >> 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 > > I would add: > > small pages over nfs: fails with or without this patch > > (tested on Juno, Cortex-A57; seems to be fixed if I remove the > PG_dcache_clean test altogether but, well, we end up over-flushing) > > I assume that when using a hard drive, it goes through the block I/O > layer and we may have a flush_dcache_page() called when the kernel is > about to read a page that has been mapped in user space. This would > clear the PG_dcache_clean bit and subsequent __sync_icache_dcache() > would perform cache maintenance. > > Could you try on your system the test case without the msync() call? I'm According to my test results: without msync, the test case may failed.
10-175-112-211:~ # ./tst_small_page_no_msync Test is Failed: The result is 0x316b9, expect = 0x365a5 10-175-112-211:~ # ./tst_small_page_no_msync Test is Failed: The result is 0x31023, expect = 0x31efa 10-175-112-211:~ # ./tst_small_page_no_msync Test is Passed: The result is 0x31efa, expect = 0x31efa 10-175-112-211:~ # ./tst_small_page Test is Passed: The result is 0x31eb7, expect = 0x31eb7 10-175-112-211:~ # ./tst_small_page Test is Passed: The result is 0x3111f, expect = 0x3111f 10-175-112-211:~ # ./tst_small_page Test is Passed: The result is 0x3111f, expect = 0x3111f > not sure whether munmap() would trigger an immediate write-back, in > which case we may see the issue even with the filesystem on a hard > drive. >
