Messages in this thread | | | Subject | Re: [PATCH 4/6] mm: hugetlb_vmemmap: add missing smp_wmb() before set_pte_at() | From | Muchun Song <> | Date | Mon, 22 Aug 2022 18:23:27 +0800 |
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> On Aug 22, 2022, at 16:45, Miaohe Lin <linmiaohe@huawei.com> wrote: > > On 2022/8/20 16:12, Muchun Song wrote: >> >> >>> On Aug 16, 2022, at 21:05, Miaohe Lin <linmiaohe@huawei.com> wrote: >>> >>> The memory barrier smp_wmb() is needed to make sure that preceding stores >>> to the page contents become visible before the below set_pte_at() write. >> >> I found another place where is a similar case. See kasan_populate_vmalloc_pte() in >> mm/kasan/shadow.c. > > Thanks for your report. > >> >> Should we fix it as well? > > I'm not familiar with kasan yet, but I think memory barrier is needed here or memory corrupt > can't be detected until the contents are visible. smp_mb__after_atomic before set_pte_at should > be enough? What's your opinion?
I didn’t see any atomic operation between set_pte_at() and memset(), I don’t think smp_mb__after_atomic() is feasible if we really need to insert a barrier. I suggest you to send a RFC patch to KASAN maintainers, they are more familiar with this than us.
Thanks.
> > Thanks, > Miaohe Lin > >
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