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From: Hugh Dickins <hughd@google.com>
To: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Hugh Dickins <hughd@google.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Vasily Gorbik <gor@linux.ibm.com>,
	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>,
	Lorenzo Stoakes <lstoakes@gmail.com>,
	Huang Ying <ying.huang@intel.com>,
	Naoya Horiguchi <naoya.horiguchi@nec.com>,
	Christophe Leroy <christophe.leroy@csgroup.eu>,
	Zack Rusin <zackr@vmware.com>, Jason Gunthorpe <jgg@ziepe.ca>,
	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>,
	Vishal Moola <vishal.moola@gmail.com>,
	Vlastimil Babka <vbabka@suse.cz>,
	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 v2 07/12] s390: add pte_free_defer() for pgtables sharing page
Date: Wed, 28 Jun 2023 22:08:08 -0700 (PDT)	[thread overview]
Message-ID: <cd7c2851-1440-7220-6c53-16b343b1474@google.com> (raw)
In-Reply-To: <20230628211624.531cdc58@thinkpad-T15>

On Wed, 28 Jun 2023, Gerald Schaefer wrote:
> 
> As discussed in the other thread, we would rather go with less complexity,
> possibly switching to an approach w/o the list and fragment re-use in the
> future. For now, as a first step in that direction, we can try with not
> adding fragments back only for pte_free_defer(). Here is an adjusted
> version of your patch, copying most of your pte_free_defer() logic and
> also description, tested with LTP and all three of your patch series applied:

Thanks, Gerald: I don't mind abandoning my 13/12 SLAB_TYPESAFE_BY_RCU
patch (posted with fewer Cc's to the s390 list last week), and switching
to your simpler who-cares-if-we-sometimes-don't-make-maximal-use-of-page
patch.

But I didn't get deep enough into it today to confirm it - and disappointed
that you've found it necessary to play with pt_frag_refcount in addition to
_refcount and HH bits.  No real problem with that, but my instinct says it
should be simpler.

Tomorrow...
Hugh

  reply	other threads:[~2023-06-29  5:08 UTC|newest]

Thread overview: 47+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-06-20  7:35 [PATCH v2 00/12] mm: free retracted page table by RCU Hugh Dickins
2023-06-20  7:40 ` [PATCH v2 01/12] mm/pgtable: add rcu_read_lock() and rcu_read_unlock()s Hugh Dickins
2023-06-20  7:42 ` [PATCH v2 02/12] mm/pgtable: add PAE safety to __pte_offset_map() Hugh Dickins
2023-06-20  7:43 ` [PATCH v2 03/12] arm: adjust_pte() use pte_offset_map_nolock() Hugh Dickins
2023-06-20  7:45 ` [PATCH v2 04/12] powerpc: assert_pte_locked() " Hugh Dickins
2023-06-20  7:47 ` [PATCH v2 05/12] powerpc: add pte_free_defer() for pgtables sharing page Hugh Dickins
2023-06-20 11:45   ` Jason Gunthorpe
2023-06-20 19:54     ` Hugh Dickins
2023-06-20 23:52       ` Jason Gunthorpe
2023-06-22  2:36         ` Hugh Dickins
2023-06-27 17:01           ` Jason Gunthorpe
2023-06-27 20:53             ` Hugh Dickins
2023-06-20  7:49 ` [PATCH v2 06/12] sparc: add pte_free_defer() for pte_t *pgtable_t Hugh Dickins
2023-06-20  7:51 ` [PATCH v2 07/12] s390: add pte_free_defer() for pgtables sharing page Hugh Dickins
2023-06-28 19:16   ` Gerald Schaefer
2023-06-29  5:08     ` Hugh Dickins [this message]
2023-06-29 15:22       ` Jason Gunthorpe
2023-06-29 15:56         ` Gerald Schaefer
2023-06-30  6:00           ` Hugh Dickins
2023-07-02  4:32             ` Hugh Dickins
2023-07-04 13:40               ` Alexander Gordeev
2023-07-04 16:03                 ` Hugh Dickins
2023-07-04 15:19               ` Gerald Schaefer
2023-07-04 17:03                 ` Hugh Dickins
2023-07-05 12:55                   ` Gerald Schaefer
2023-07-06  1:20                     ` Hugh Dickins
2023-07-06 15:02                       ` Gerald Schaefer
2023-07-06 19:45                         ` Hugh Dickins
2023-07-10 17:21                     ` Jason Gunthorpe
2023-07-05  6:46               ` Alexander Gordeev
2023-07-06  0:52                 ` Hugh Dickins
2023-07-07 14:37                   ` Gerald Schaefer
2023-07-03 16:10             ` Gerald Schaefer
2023-06-29 13:59     ` Alexander Gordeev
2023-06-29 15:43       ` Gerald Schaefer
2023-06-30 13:38   ` Claudio Imbrenda
2023-06-30 15:28     ` Hugh Dickins
2023-06-30 16:25       ` Claudio Imbrenda
2023-06-30 19:22         ` Hugh Dickins
2023-07-03 11:00           ` Claudio Imbrenda
2023-07-03 21:29             ` Jason Gunthorpe
2023-06-20  7:53 ` [PATCH v2 08/12] mm/pgtable: add pte_free_defer() for pgtable as page Hugh Dickins
2023-06-20  7:54 ` [PATCH v2 09/12] mm/khugepaged: retract_page_tables() without mmap or vma lock Hugh Dickins
2023-06-20  7:56 ` [PATCH v2 10/12] mm/khugepaged: collapse_pte_mapped_thp() with mmap_read_lock() Hugh Dickins
2023-06-20  8:04   ` [PATCH mm " Hugh Dickins
2023-06-20  7:58 ` [PATCH v2 11/12] mm/khugepaged: delete khugepaged_collapse_pte_mapped_thps() Hugh Dickins
2023-06-20  7:59 ` [PATCH v2 12/12] mm: delete mmap_write_trylock() and vma_try_start_write() Hugh Dickins

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