From: Jason Gunthorpe <jgg@ziepe•ca>
To: Jann Horn <jannh@google•com>
Cc: Miaohe Lin <linmiaohe@huawei•com>,
David Hildenbrand <david@redhat•com>,
Peter Zijlstra <peterz@infradead•org>,
Yang Shi <shy828301@gmail•com>, Peter Xu <peterx@redhat•com>,
linux-kernel@vger•kernel.org, Song Liu <song@kernel•org>,
sparclinux@vger•kernel.org,
Alexander Gordeev <agordeev@linux•ibm.com>,
Claudio Imbrenda <imbrenda@linux•ibm.com>,
Will Deacon <will@kernel•org>,
linux-s390@vger•kernel.org, Yu Zhao <yuzhao@google•com>,
Ira Weiny <ira.weiny@intel•com>,
Alistair Popple <apopple@nvidia•com>,
Hugh Dickins <hughd@google•com>,
Russell King <linux@armlinux•org.uk>,
Matthew Wilcox <willy@infradead•org>,
Steven Price <steven.price@arm•com>,
Christoph Hellwig <hch@infradead•org>,
"Aneesh Kumar K.V" <aneesh.kumar@linux•ibm.com>,
Axel Rasmussen <axelrasmussen@google•com>,
Christian Borntraeger <borntraeger@linux•ibm.com>,
Thomas Hellstrom <thomas.hellstrom@linux•intel.com>,
Ralph Campbell <rcampbell@nvidia•com>,
Pasha Tatashin <pasha.tatashin@soleen•com>,
Anshuman Khandual <anshu man.khandual@arm•com>,
Heiko Carstens <hca@linux•ibm.com>,
Qi Zheng <zhengqi.arch@bytedance•com>,
Suren Baghdasaryan <surenb@google•com>,
linux-arm-kernel@lists•infradead.org,
SeongJae Park <sj@kernel•org>,
linux-mm@kvack•org, linuxppc-dev@lists•ozlabs.org,
Naoya Horiguchi <naoya.horiguchi@nec•com>,
Zack Rusin <zackr@vmware•com>, Minchan Kim <minchan@kernel•org>,
"Kirill A. Shutemov" <kirill.shutemov@linux•intel.com>,
Andrew Morton <akpm@linux-foundation•org>,
Mel Gorman <mgorman@techsingularity•net>,
"David S. Miller" <davem@davemloft•net>,
Mike Rapoport <rppt@kernel•org>,
Mike Kravetz <mike.kravetz@oracle•com>
Subject: Re: [PATCH 09/12] mm/khugepaged: retract_page_tables() without mmap or vma lock
Date: Thu, 1 Jun 2023 11:06:57 -0300 [thread overview]
Message-ID: <ZHimAWRNDTg1JPOp@ziepe.ca> (raw)
In-Reply-To: <CAG48ez1UNFfpTUph6ZMuN61CoTGne05NLAweL_=ijRfqj5evMg@mail.gmail.com>
On Thu, Jun 01, 2023 at 12:18:43AM +0200, Jann Horn wrote:
> 3. We have to *serialize* with page table walks performed by the
> IOMMU. We're doing an RCU barrier to synchronize against page table
> walks from the MMU, but without an appropriate mmu_notifier call, we
> have nothing to ensure that we aren't yanking a page table out from
> under an IOMMU page table walker while it's in the middle of its walk.
> Sure, this isn't very likely in practice, the IOMMU page table walker
> is probably pretty fast, but still we need some kind of explicit
> synchronization to make this robust, I think.
There is another thread talking about this..
Broadly we are saying that we need to call mmu ops invalidate_range at
any time the normal CPU TLB would be invalidated.
invalidate_range will not return until the iommu HW is coherent with
the current state of the page table.
Jason
next prev parent reply other threads:[~2023-06-01 14:07 UTC|newest]
Thread overview: 50+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-05-29 6:11 [PATCH 00/12] mm: free retracted page table by RCU Hugh Dickins
2023-05-29 6:14 ` [PATCH 01/12] mm/pgtable: add rcu_read_lock() and rcu_read_unlock()s Hugh Dickins
2023-05-31 17:06 ` Jann Horn
2023-06-02 2:50 ` Hugh Dickins
2023-06-02 14:21 ` Jann Horn
2023-05-29 6:16 ` [PATCH 02/12] mm/pgtable: add PAE safety to __pte_offset_map() Hugh Dickins
2023-05-29 13:56 ` Matthew Wilcox
[not found] ` <ZHeg3oRljRn6wlLX@ziepe.ca>
2023-06-02 5:35 ` Hugh Dickins
2023-05-29 6:17 ` [PATCH 03/12] arm: adjust_pte() use pte_offset_map_nolock() Hugh Dickins
2023-05-29 6:18 ` [PATCH 04/12] powerpc: assert_pte_locked() " Hugh Dickins
2023-05-29 6:20 ` [PATCH 05/12] powerpc: add pte_free_defer() for pgtables sharing page Hugh Dickins
2023-05-29 14:02 ` Matthew Wilcox
2023-05-29 14:36 ` Hugh Dickins
2023-06-01 13:57 ` Gerald Schaefer
2023-06-02 6:38 ` Hugh Dickins
2023-06-02 14:20 ` Jason Gunthorpe
2023-06-06 3:40 ` Hugh Dickins
2023-06-06 18:23 ` Jason Gunthorpe
2023-06-06 19:03 ` Peter Xu
2023-06-06 19:08 ` Jason Gunthorpe
2023-06-07 3:49 ` Hugh Dickins
2023-05-29 6:21 ` [PATCH 06/12] sparc: " Hugh Dickins
2023-06-06 3:46 ` Hugh Dickins
2023-05-29 6:22 ` [PATCH 07/12] s390: add pte_free_defer(), with use of mmdrop_async() Hugh Dickins
2023-06-06 5:11 ` Hugh Dickins
2023-06-06 18:39 ` Jason Gunthorpe
2023-06-08 2:46 ` Hugh Dickins
2023-06-06 19:40 ` Gerald Schaefer
2023-06-08 3:35 ` Hugh Dickins
2023-06-08 13:58 ` Jason Gunthorpe
2023-06-08 15:47 ` Gerald Schaefer
2023-05-29 6:23 ` [PATCH 08/12] mm/pgtable: add pte_free_defer() for pgtable as page Hugh Dickins
2023-06-01 13:31 ` Jann Horn
[not found] ` <ZHekpAKJ05cr/GLl@ziepe.ca>
2023-06-02 6:03 ` Hugh Dickins
2023-06-02 12:15 ` Jason Gunthorpe
2023-05-29 6:25 ` [PATCH 09/12] mm/khugepaged: retract_page_tables() without mmap or vma lock Hugh Dickins
2023-05-29 23:26 ` Peter Xu
2023-05-31 0:38 ` Hugh Dickins
2023-05-31 15:34 ` Jann Horn
[not found] ` <ZHe0A079X9B8jWlH@x1n>
2023-05-31 22:18 ` Jann Horn
2023-06-01 14:06 ` Jason Gunthorpe [this message]
2023-06-06 6:18 ` Hugh Dickins
2023-05-29 6:26 ` [PATCH 10/12] mm/khugepaged: collapse_pte_mapped_thp() with mmap_read_lock() Hugh Dickins
2023-05-31 17:25 ` Jann Horn
2023-06-02 5:11 ` Hugh Dickins
2023-05-29 6:28 ` [PATCH 11/12] mm/khugepaged: delete khugepaged_collapse_pte_mapped_thps() Hugh Dickins
2023-05-29 6:30 ` [PATCH 12/12] mm: delete mmap_write_trylock() and vma_try_start_write() Hugh Dickins
[not found] ` <CAG48ez0pCqfRdVSnJz7EKtNvMR65=zJgVB-72nTdrNuhtJNX2Q@mail.gmail.com>
2023-06-02 4:37 ` [PATCH 00/12] mm: free retracted page table by RCU Hugh Dickins
2023-06-02 15:26 ` Jann Horn
2023-06-06 6:28 ` Hugh Dickins
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