From: Jason Gunthorpe <jgg@ziepe.ca>
To: Peter Xu <peterx@redhat.com>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Matthew Wilcox <willy@infradead.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Kirill Tkhai <ktkhai@virtuozzo.com>,
Mike Rapoport <rppt@linux.vnet.ibm.com>,
David Gibson <david@gibson.dropbear.id.au>,
Kirill Shutemov <kirill@shutemov.name>,
Christoph Hellwig <hch@lst.de>, Miaohe Lin <linmiaohe@huawei.com>,
Gal Pressman <galpress@amazon.com>, Jann Horn <jannh@google.com>,
Jan Kara <jack@suse.cz>, Wei Zhang <wzam@amazon.com>,
Mike Kravetz <mike.kravetz@oracle.com>,
Andrea Arcangeli <aarcange@redhat.com>,
Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH v4 5/5] hugetlb: Do early cow when page pinned on src mm
Date: Tue, 9 Feb 2021 13:54:24 -0400 [thread overview]
Message-ID: <20210209175424.GK4718@ziepe.ca> (raw)
In-Reply-To: <20210209030229.84991-6-peterx@redhat.com>
On Mon, Feb 08, 2021 at 10:02:29PM -0500, Peter Xu wrote:
> This is the last missing piece of the COW-during-fork effort when there're
> pinned pages found. One can reference 70e806e4e645 ("mm: Do early cow for
> pinned pages during fork() for ptes", 2020-09-27) for more information, since
> we do similar things here rather than pte this time, but just for hugetlb.
>
> Note that after Jason's recent work on 57efa1fe5957 ("mm/gup: prevent gup_fast
> from racing with COW during fork", 2020-12-15) which is safer and easier to
> understand, we're safe now within the whole copy_page_range() against gup-fast,
> we don't need the wr-protect trick that proposed in 70e806e4e645 anymore.
>
> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
> Signed-off-by: Peter Xu <peterx@redhat.com>
> ---
> mm/hugetlb.c | 66 ++++++++++++++++++++++++++++++++++++++++++++++++----
> 1 file changed, 62 insertions(+), 4 deletions(-)
Didn't check every hugetlbfs detail, but looks reasonable
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Jason
prev parent reply other threads:[~2021-02-09 17:54 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-09 3:02 [PATCH v4 0/5] mm/hugetlb: Early cow on fork, and a few cleanups Peter Xu
2021-02-09 3:02 ` [PATCH v4 1/5] hugetlb: Dedup the code to add a new file_region Peter Xu
2021-02-09 3:02 ` [PATCH v4 2/5] hugetlg: Break earlier in add_reservation_in_range() when we can Peter Xu
2021-02-09 3:02 ` [PATCH v4 3/5] mm: Introduce page_needs_cow_for_dma() for deciding whether cow Peter Xu
2021-02-09 17:40 ` Jason Gunthorpe
2021-02-09 3:02 ` [PATCH v4 4/5] mm: Use is_cow_mapping() across tree where proper Peter Xu
2021-02-09 17:46 ` Jason Gunthorpe
2021-02-09 3:02 ` [PATCH v4 5/5] hugetlb: Do early cow when page pinned on src mm Peter Xu
2021-02-09 17:54 ` Jason Gunthorpe [this message]
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