From: Mike Kravetz <mike.kravetz@oracle.com>
To: Muchun Song <songmuchun@bytedance.com>,
akpm@linux-foundation.org, zi.yan@cs.rutgers.edu,
kirill.shutemov@linux.intel.com, rientjes@google.com,
lars.persson@axis.com, ziy@nvidia.com
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
duanxiongchun@bytedance.com, fam.zheng@bytedance.com
Subject: Re: [PATCH v4 3/5] mm: hugetlb: fix missing cache flush in copy_huge_page_from_user()
Date: Wed, 9 Feb 2022 11:07:07 -0800 [thread overview]
Message-ID: <d78d6e56-1879-94c8-dc28-06431e583a77@oracle.com> (raw)
In-Reply-To: <20220208073617.70342-4-songmuchun@bytedance.com>
On 2/7/22 23:36, Muchun Song wrote:
> The userfaultfd calls copy_huge_page_from_user() which does not do
> any cache flushing for the target page. Then the target page will
> be mapped to the user space with a different address (user address),
> which might have an alias issue with the kernel address used to copy
> the data from the user to. Fix this issue by flushing dcache in
> copy_huge_page_from_user().
Quick question.
Should this also be done for the non-hugetlb case? Take a look at the
routines __mcopy_atomic() and mcopy_atomic_pte(). Or, is that somehow
handled?
For this change,
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
--
Mike Kravetz
>
> Fixes: fa4d75c1de13 ("userfaultfd: hugetlbfs: add copy_huge_page_from_user for hugetlb userfaultfd support")
> Signed-off-by: Muchun Song <songmuchun@bytedance.com>
> ---
> mm/memory.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/mm/memory.c b/mm/memory.c
> index e8ce066be5f2..eb027da68aa7 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -5405,6 +5405,8 @@ long copy_huge_page_from_user(struct page *dst_page,
> if (rc)
> break;
>
> + flush_dcache_page(subpage);
> +
> cond_resched();
> }
> return ret_val;
next prev parent reply other threads:[~2022-02-09 19:07 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-08 7:36 [PATCH v4 0/5] Fix some cache flush bugs Muchun Song
2022-02-08 7:36 ` [PATCH v4 1/5] mm: thp: fix wrong cache flush in remove_migration_pmd() Muchun Song
2022-02-08 7:36 ` [PATCH v4 2/5] mm: fix missing cache flush for all tail pages of compound page Muchun Song
2022-02-08 7:36 ` [PATCH v4 3/5] mm: hugetlb: fix missing cache flush in copy_huge_page_from_user() Muchun Song
2022-02-09 19:07 ` Mike Kravetz [this message]
2022-02-10 7:19 ` Muchun Song
2022-02-08 7:36 ` [PATCH v4 4/5] mm: hugetlb: fix missing cache flush in hugetlb_mcopy_atomic_pte() Muchun Song
2022-02-09 18:59 ` Mike Kravetz
2022-02-08 7:36 ` [PATCH v4 5/5] mm: replace multiple dcache flush with flush_dcache_folio() Muchun Song
2022-02-09 19:10 ` Mike Kravetz
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