From: Peter Xu <peterx@redhat.com>
To: Yang Shi <shy828301@gmail.com>
Cc: David Hildenbrand <david@redhat.com>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
"Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
Sasha Levin <sasha.levin@oracle.com>,
"Aneesh Kumar K . V" <aneesh.kumar@linux.vnet.ibm.com>,
Vlastimil Babka <vbabka@suse.cz>,
Jerome Marchand <jmarchan@redhat.com>,
Andrea Arcangeli <aarcange@redhat.com>,
Hugh Dickins <hughd@google.com>, Jason Gunthorpe <jgg@nvidia.com>,
John Hubbard <jhubbard@nvidia.com>
Subject: Re: [PATCH v1] mm/gup: adjust stale comment for RCU GUP-fast
Date: Thu, 1 Sep 2022 14:07:12 -0400 [thread overview]
Message-ID: <YxD00K1lv151X/eq@xz-m1.local> (raw)
In-Reply-To: <CAHbLzkpdUMq2fMxqx-NgSZ2VLBU5RGqSpJRWH6eRrYymErAbaw@mail.gmail.com>
On Thu, Sep 01, 2022 at 10:50:48AM -0700, Yang Shi wrote:
> Yeah, because THP collapse does copy the data before clearing pte. If
> we want to remove pmdp_collapse_flush() by just clearing pmd, we
> should clear *AND* flush pte before copying the data IIRC.
Yes tlb flush is still needed. IIUC the generic pmdp_collapse_flush() will
still be working (with the pte level flushing there) but it should just
start to work for all archs, so potentially we could drop the arch-specific
pmdp_collapse_flush()s, mostly the ppc impl.
This also reminded me that the s390 version of pmdp_collapse_flush() is a
bit weird, since it doesn't even have the tlb flush there. I feel like
it's broken but I can't really tell whether something I've overlooked.
Worth an eye on.
--
Peter Xu
next prev parent reply other threads:[~2022-09-01 18:07 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-01 7:21 David Hildenbrand
2022-09-01 14:37 ` Kirill A . Shutemov
2022-09-01 16:12 ` Jason Gunthorpe
2022-09-01 16:30 ` David Hildenbrand
2022-09-01 16:28 ` Peter Xu
2022-09-01 16:34 ` David Hildenbrand
2022-09-01 16:40 ` Peter Xu
2022-09-01 16:46 ` David Hildenbrand
2022-09-01 17:41 ` Peter Xu
2022-09-01 17:44 ` David Hildenbrand
2022-09-01 17:50 ` Yang Shi
2022-09-01 18:07 ` Peter Xu [this message]
2022-09-01 18:35 ` Yang Shi
2022-09-02 6:32 ` David Hildenbrand
2022-09-02 13:53 ` Peter Xu
2022-09-02 15:37 ` Yang Shi
2022-09-04 16:52 ` Aneesh Kumar K V
2022-09-05 8:38 ` David Hildenbrand
2022-09-05 8:41 ` Aneesh Kumar K V
2022-09-04 16:49 ` Aneesh Kumar K V
2022-09-05 8:02 ` David Hildenbrand
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