Re: [PATCH] mm/gup: Use put_user_page*() instead of put_page*()

From: Bharath Vedartham <linux.bhar@gmail.com>
To: Jens Axboe <axboe@kernel.dk>
Cc: akpm@linux-foundation.org, ira.weiny@intel.com,
	jhubbard@nvidia.com, "Mauro Carvalho Chehab" <mchehab@kernel.org>,
	"Dimitri Sivanich" <sivanich@sgi.com>,
	"Arnd Bergmann" <arnd@arndb.de>,
	"Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
	"Alex Williamson" <alex.williamson@redhat.com>,
	"Cornelia Huck" <cohuck@redhat.com>,
	"Alexander Viro" <viro@zeniv.linux.org.uk>,
	"Björn Töpel" <bjorn.topel@intel.com>,
	"Magnus Karlsson" <magnus.karlsson@intel.com>,
	"David S. Miller" <davem@davemloft.net>,
	"Alexei Starovoitov" <ast@kernel.org>,
	"Daniel Borkmann" <daniel@iogearbox.net>,
	"Jakub Kicinski" <jakub.kicinski@netronome.com>,
	"Jesper Dangaard Brouer" <hawk@kernel.org>,
	"John Fastabend" <john.fastabend@gmail.com>,
	"Enrico Weigelt" <info@metux.net>,
	"Thomas Gleixner" <tglx@linutronix.de>,
	"Alexios Zavras" <alexios.zavras@intel.com>,
	"Dan Carpenter" <dan.carpenter@oracle.com>,
	"Max Filippov" <jcmvbkbc@gmail.com>,
	"Matt Sickler" <Matt.Sickler@daktronics.com>,
	"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
	"Keith Busch" <keith.busch@intel.com>,
	YueHaibing <yuehaibing@huawei.com>,
	linux-media@vger.kernel.org, linux-kernel@vger.kernel.org,
	devel@driverdev.osuosl.org, kvm@vger.kernel.org,
	linux-block@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	linux-mm@kvack.org, netdev@vger.kernel.org, bpf@vger.kernel.org,
	xdp-newbies@vger.kernel.org
Subject: Re: [PATCH] mm/gup: Use put_user_page*() instead of put_page*()
Date: Mon, 15 Jul 2019 12:29:17 +0530	[thread overview]
Message-ID: <20190715065917.GB3716@bharath12345-Inspiron-5559> (raw)
In-Reply-To: <018ee3d1-e2f0-ca12-9f63-945056c09985@kernel.dk>

On Sun, Jul 14, 2019 at 08:33:57PM -0600, Jens Axboe wrote:
> On 7/14/19 1:08 PM, Bharath Vedartham wrote:
> > diff --git a/fs/io_uring.c b/fs/io_uring.c
> > index 4ef62a4..b4a4549 100644
> > --- a/fs/io_uring.c
> > +++ b/fs/io_uring.c
> > @@ -2694,10 +2694,9 @@ static int io_sqe_buffer_register(struct io_ring_ctx *ctx, void __user *arg,
> >   			 * if we did partial map, or found file backed vmas,
> >   			 * release any pages we did get
> >   			 */
> > -			if (pret > 0) {
> > -				for (j = 0; j < pret; j++)
> > -					put_page(pages[j]);
> > -			}
> > +			if (pret > 0)
> > +				put_user_pages(pages, pret);
> > +
> >   			if (ctx->account_mem)
> >   				io_unaccount_mem(ctx->user, nr_pages);
> >   			kvfree(imu->bvec);
> 
> You handled just the failure case of the buffer registration, but not
> the actual free in io_sqe_buffer_unregister().
> 
> -- 
> Jens Axboe
Yup got it! Thanks! I won't be sending a patch again as fs/io_uring.c
may have larger local changes for put_user_pages.

Thanks