From: "Björn Töpel" <bjorn.topel@gmail.com>
To: akpm@linux-foundation.org, linux-mm@kvack.org,
LKML <linux-kernel@vger.kernel.org>,
"David S . Miller" <davem@davemloft.net>,
Bjorn Topel <bjorn.topel@intel.com>,
Magnus Karlsson <magnus.karlsson@intel.com>,
Netdev <netdev@vger.kernel.org>, Davidlohr Bueso <dbueso@suse.de>
Subject: Re: [PATCH v2] xsk: share the mmap_sem for page pinning
Date: Mon, 11 Feb 2019 17:21:49 +0100 [thread overview]
Message-ID: <CAJ+HfNj3jwqT7980grynDp7sPj6XL8_JFgs5AK6Zhhj7spRpTg@mail.gmail.com> (raw)
In-Reply-To: <20190211161529.uskq5ca7y3j5522i@linux-r8p5>
Den mån 11 feb. 2019 kl 17:15 skrev Davidlohr Bueso <dave@stgolabs.net>:
>
> Holding mmap_sem exclusively for a gup() is an overkill.
> Lets share the lock and replace the gup call for gup_longterm(),
> as it is better suited for the lifetime of the pinning.
>
Thanks for the cleanup!
Acked-by: Björn Töpel <bjorn.topel@intel.com>
> Cc: David S. Miller <davem@davemloft.net>
> Cc: Bjorn Topel <bjorn.topel@intel.com>
> Cc: Magnus Karlsson <magnus.karlsson@intel.com>
> CC: netdev@vger.kernel.org
> Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
> ---
> net/xdp/xdp_umem.c | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/net/xdp/xdp_umem.c b/net/xdp/xdp_umem.c
> index 5ab236c5c9a5..e7fa8d0d7090 100644
> --- a/net/xdp/xdp_umem.c
> +++ b/net/xdp/xdp_umem.c
> @@ -265,10 +265,10 @@ static int xdp_umem_pin_pages(struct xdp_umem *umem)
> if (!umem->pgs)
> return -ENOMEM;
>
> - down_write(¤t->mm->mmap_sem);
> - npgs = get_user_pages(umem->address, umem->npgs,
> + down_read(¤t->mm->mmap_sem);
> + npgs = get_user_pages_longterm(umem->address, umem->npgs,
> gup_flags, &umem->pgs[0], NULL);
> - up_write(¤t->mm->mmap_sem);
> + up_read(¤t->mm->mmap_sem);
>
> if (npgs != umem->npgs) {
> if (npgs >= 0) {
> --
> 2.16.4
>
next prev parent reply other threads:[~2019-02-11 16:22 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-07 5:37 [PATCH -tip 0/2] more get_user_pages mmap_sem cleanups Davidlohr Bueso
2019-02-07 5:37 ` [PATCH 1/2] xsk: do not use mmap_sem Davidlohr Bueso
2019-02-07 7:43 ` Björn Töpel
2019-02-11 15:33 ` Daniel Borkmann
2019-02-11 16:37 ` Dan Williams
2019-02-11 17:16 ` Weiny, Ira
2019-02-11 16:15 ` [PATCH v2] xsk: share the mmap_sem for page pinning Davidlohr Bueso
2019-02-11 16:21 ` Björn Töpel [this message]
2019-02-11 19:53 ` Daniel Borkmann
2019-02-07 5:37 ` [PATCH 2/2] MIPS/c-r4k: do no use mmap_sem for gup_fast() Davidlohr Bueso
2019-02-07 19:00 ` Paul Burton
2019-02-07 19:25 ` Davidlohr Bueso
2019-02-07 5:50 ` [PATCH -tip 0/2] more get_user_pages mmap_sem cleanups Davidlohr Bueso
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