From: catalin.marinas@arm.com (Catalin Marinas)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 1/1] arm64/hugetlb: clear PG_dcache_clean if the page is dirty when munmap
Date: Wed, 20 Jul 2016 10:19:39 +0100 [thread overview]
Message-ID: <20160720091939.GA25890@e104818-lin.cambridge.arm.com> (raw)
In-Reply-To: <578EE603.9020206@huawei.com>
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
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.
--
Catalin
next prev parent reply other threads:[~2016-07-20 9:19 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-07-07 12:09 [PATCH 1/1] arm64/hugetlb: clear PG_dcache_clean if the page is dirty when munmap Zhen Lei
2016-07-07 15:37 ` Catalin Marinas
2016-07-08 3:36 ` Leizhen (ThunderTown)
2016-07-08 13:54 ` Catalin Marinas
2016-07-08 15:24 ` Leizhen (ThunderTown)
2016-07-08 16:13 ` Catalin Marinas
2016-07-11 12:43 ` Leizhen (ThunderTown)
2016-07-12 15:35 ` Catalin Marinas
2016-07-20 2:46 ` Leizhen (ThunderTown)
2016-07-20 9:19 ` Catalin Marinas [this message]
2016-08-22 4:19 ` Leizhen (ThunderTown)
2016-08-23 17:28 ` Catalin Marinas
2016-08-24 1:30 ` Leizhen (ThunderTown)
2016-08-24 9:00 ` Leizhen (ThunderTown)
2016-08-24 10:30 ` Catalin Marinas
2016-08-25 1:42 ` Leizhen (ThunderTown)
2016-08-25 9:30 ` Catalin Marinas
2016-08-25 11:27 ` Leizhen (ThunderTown)
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