Messages in this thread | | | Subject | Re: [PATCH 1/1] arm64/hugetlb: clear PG_dcache_clean if the page is dirty when munmap | From | "Leizhen (ThunderTown)" <> | Date | Thu, 25 Aug 2016 19:27:47 +0800 |
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On 2016/8/25 17:30, Catalin Marinas wrote: > On Thu, Aug 25, 2016 at 09:42:26AM +0800, Leizhen (ThunderTown) wrote: >> On 2016/8/24 18:30, Catalin Marinas 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<--------------------- > [...] >>> While we indeed see failures on multiple filesystem types, I wonder >>> whether this test case is actually expected to work. If I modify the >>> test to pass O_TRUNC to open(), I can no longer see failures. So any >>> standard tool that copies/creates executable files (gcc, dpkg, cp, rsync >>> etc.) wouldn't encounter such issues since they truncate the original >>> file and old page cache pages would be removed. >>> >>> Do you have a real use-case where a task mmap's an executable file, >>> modifies it in place and expects another task to see the new >>> instructions without user-space cache maintenance? >> >> No, it's just a test case created by testers. > > In this case I propose we ignore this patch and you adjust the test to > use O_TRUNC, at least until we find a real scenario where this would > matter. OK, thanks. We currently add __clear_cache in user space.
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