From: Jason Gunthorpe <jgg@ziepe.ca>
To: Peter Xu <peterx@redhat.com>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Kirill Shutemov <kirill@shutemov.name>,
Wei Zhang <wzam@amazon.com>,
Mike Rapoport <rppt@linux.vnet.ibm.com>,
Matthew Wilcox <willy@infradead.org>,
Miaohe Lin <linmiaohe@huawei.com>,
Andrea Arcangeli <aarcange@redhat.com>,
Gal Pressman <galpress@amazon.com>, Jan Kara <jack@suse.cz>,
Jann Horn <jannh@google.com>,
Andrew Morton <akpm@linux-foundation.org>,
Kirill Tkhai <ktkhai@virtuozzo.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Mike Kravetz <mike.kravetz@oracle.com>,
David Gibson <david@gibson.dropbear.id.au>,
Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH v2 3/4] mm: Introduce page_needs_cow_for_dma() for deciding whether cow
Date: Thu, 4 Feb 2021 19:20:00 -0400 [thread overview]
Message-ID: <20210204232000.GG4718@ziepe.ca> (raw)
In-Reply-To: <20210204145033.136755-4-peterx@redhat.com>
On Thu, Feb 04, 2021 at 09:50:32AM -0500, Peter Xu wrote:
> We've got quite a few places (pte, pmd, pud) that explicitly checked against
> whether we should break the cow right now during fork(). It's easier to
> provide a helper, especially before we work the same thing on hugetlbfs.
>
> Since we'll reference is_cow_mapping() in mm.h, move it there too. Actually it
> suites mm.h more since internal.h is mm/ only, but mm.h is exported to the
> whole kernel. With that we should expect another patch to use is_cow_mapping()
> whenever we can across the kernel since we do use it quite a lot but it's
> always done with raw code against VM_* flags.
>
> Signed-off-by: Peter Xu <peterx@redhat.com>
> include/linux/mm.h | 21 +++++++++++++++++++++
> mm/huge_memory.c | 8 ++------
> mm/internal.h | 5 -----
> mm/memory.c | 7 +------
> 4 files changed, 24 insertions(+), 17 deletions(-)
>
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index ecdf8a8cd6ae..6ea20721d349 100644
> +++ b/include/linux/mm.h
> @@ -1291,6 +1291,27 @@ static inline bool page_maybe_dma_pinned(struct page *page)
> GUP_PIN_COUNTING_BIAS;
> }
>
> +static inline bool is_cow_mapping(vm_flags_t flags)
> +{
It feels a bit more logical to pass in a struct vm_area_struct *' here?
Jason
next prev parent reply other threads:[~2021-02-04 23:21 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-04 14:50 [PATCH v2 0/4] mm/hugetlb: Early cow on fork, and a few cleanups Peter Xu
2021-02-04 14:50 ` [PATCH v2 1/4] hugetlb: Dedup the code to add a new file_region Peter Xu
2021-02-04 14:50 ` [PATCH v2 2/4] hugetlg: Break earlier in add_reservation_in_range() when we can Peter Xu
2021-02-04 14:50 ` [PATCH v2 3/4] mm: Introduce page_needs_cow_for_dma() for deciding whether cow Peter Xu
2021-02-04 17:54 ` Linus Torvalds
2021-02-04 19:25 ` Peter Xu
2021-02-04 23:20 ` Jason Gunthorpe [this message]
2021-02-05 0:50 ` Peter Xu
2021-02-04 14:50 ` [PATCH v2 4/4] hugetlb: Do early cow when page pinned on src mm Peter Xu
2021-02-04 23:25 ` Mike Kravetz
2021-02-05 1:43 ` Peter Xu
2021-02-05 5:11 ` Mike Kravetz
2021-02-05 16:05 ` Peter Xu
[not found] ` <329ADC08-552E-423B-9230-99643B81C14A@amazon.com>
2021-02-05 15:51 ` Peter Xu
2021-02-07 9:09 ` Gal Pressman
2021-02-07 15:31 ` Peter Xu
2021-02-04 20:20 ` [PATCH v2 5/4] mm: Use is_cow_mapping() across tree where proper Peter Xu
2021-02-04 20:26 ` Linus Torvalds
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