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From: Hugh Dickins <hughd@google.com>
To: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Hugh Dickins <hughd@google.com>,
	 Gerald Schaefer <gerald.schaefer@linux.ibm.com>,
	 Vasily Gorbik <gor@linux.ibm.com>,
	 Andrew Morton <akpm@linux-foundation.org>,
	 Mike Kravetz <mike.kravetz@oracle.com>,
	Mike Rapoport <rppt@kernel.org>,
	 "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
	 Matthew Wilcox <willy@infradead.org>,
	David Hildenbrand <david@redhat.com>,
	 Suren Baghdasaryan <surenb@google.com>,
	 Qi Zheng <zhengqi.arch@bytedance.com>,
	Yang Shi <shy828301@gmail.com>,
	 Mel Gorman <mgorman@techsingularity.net>,
	Peter Xu <peterx@redhat.com>,
	 Peter Zijlstra <peterz@infradead.org>,
	Will Deacon <will@kernel.org>,  Yu Zhao <yuzhao@google.com>,
	Alistair Popple <apopple@nvidia.com>,
	 Ralph Campbell <rcampbell@nvidia.com>,
	Ira Weiny <ira.weiny@intel.com>,
	 Steven Price <steven.price@arm.com>,
	SeongJae Park <sj@kernel.org>,
	 Naoya Horiguchi <naoya.horiguchi@nec.com>,
	 Christophe Leroy <christophe.leroy@csgroup.eu>,
	 Zack Rusin <zackr@vmware.com>,
	Axel Rasmussen <axelrasmussen@google.com>,
	 Anshuman Khandual <anshuman.khandual@arm.com>,
	 Pasha Tatashin <pasha.tatashin@soleen.com>,
	 Miaohe Lin <linmiaohe@huawei.com>,
	Minchan Kim <minchan@kernel.org>,
	 Christoph Hellwig <hch@infradead.org>,
	Song Liu <song@kernel.org>,
	 Thomas Hellstrom <thomas.hellstrom@linux.intel.com>,
	 Russell King <linux@armlinux.org.uk>,
	 "David S. Miller" <davem@davemloft.net>,
	 Michael Ellerman <mpe@ellerman.id.au>,
	 "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>,
	 Heiko Carstens <hca@linux.ibm.com>,
	 Christian Borntraeger <borntraeger@linux.ibm.com>,
	 Claudio Imbrenda <imbrenda@linux.ibm.com>,
	 Alexander Gordeev <agordeev@linux.ibm.com>,
	Jann Horn <jannh@google.com>,
	 linux-arm-kernel@lists.infradead.org,
	sparclinux@vger.kernel.org,  linuxppc-dev@lists.ozlabs.org,
	linux-s390@vger.kernel.org,  linux-kernel@vger.kernel.org,
	linux-mm@kvack.org
Subject: Re: [PATCH 07/12] s390: add pte_free_defer(), with use of mmdrop_async()
Date: Wed, 7 Jun 2023 19:46:26 -0700 (PDT)	[thread overview]
Message-ID: <ed24b58f-ef9f-2427-7372-5c77378c5b40@google.com> (raw)
In-Reply-To: <ZH99cLKeALvUCIH8@ziepe.ca>

On Tue, 6 Jun 2023, Jason Gunthorpe wrote:
> On Mon, Jun 05, 2023 at 10:11:52PM -0700, Hugh Dickins wrote:
> 
> > "deposited" pagetable fragments, over in arch/s390/mm/pgtable.c: use
> > the first two longs of the page table itself for threading the list.
> 
> It is not RCU anymore if it writes to the page table itself before the
> grace period, so this change seems to break the RCU behavior of
> page_table_free_rcu().. The rcu sync is inside tlb_remove_table()
> called after the stores.

Yes indeed, thanks for pointing that out.

> 
> Maybe something like an xarray on the mm to hold the frags?

I think we can manage without that:
I'll say slightly more in reply to Gerald.

Hugh


  parent reply	other threads:[~2023-06-08  2:46 UTC|newest]

Thread overview: 27+ 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
2023-05-29  6:16 ` [PATCH 02/12] mm/pgtable: add PAE safety to __pte_offset_map() Hugh Dickins
2023-05-29 13:56   ` Matthew Wilcox
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
     [not found]     ` <ZHn6n5eVTsr4Wl8x@ziepe.ca>
     [not found]       ` <4df4909f-f5dd-6f94-9792-8f2949f542b3@google.com>
     [not found]         ` <ZH95oobIqN0WO5MK@ziepe.ca>
     [not found]           ` <ZH+DAxLhIYpTlIFc@x1n>
     [not found]             ` <ZH+EMp9RuEVOjVNb@ziepe.ca>
2023-06-07  3:49               ` Hugh Dickins
2023-05-29  6:21 ` [PATCH 06/12] sparc: " Hugh Dickins
2023-05-29  6:22 ` [PATCH 07/12] s390: add pte_free_defer(), with use of mmdrop_async() Hugh Dickins
     [not found]   ` <175ebec8-761-c3f-2d98-6c3bd87161c8@google.com>
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
     [not found]     ` <ZH99cLKeALvUCIH8@ziepe.ca>
2023-06-08  2:46       ` Hugh Dickins [this message]
2023-05-29  6:23 ` [PATCH 08/12] mm/pgtable: add pte_free_defer() for pgtable as page Hugh Dickins
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
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
2023-05-29  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

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