Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Date:   Fri, 30 Aug 2019 08:29:10 +0200
From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     Tyler Hicks <tyhicks@canonical.com>
Cc:     Sasha Levin <sashal@kernel.org>, linux-kernel@vger.kernel.org,
        stable@vger.kernel.org, Todd Kjos <tkjos@android.com>,
        devel@driverdev.osuosl.org
Subject: Re: [PATCH AUTOSEL 4.19 11/29] binder: take read mode of mmap_sem in
 binder_alloc_free_page()
Message-ID: <20190830062910.GC15257@kroah.com>
References: <20190829105009.2265-1-sashal@kernel.org>
 <20190829105009.2265-11-sashal@kernel.org>
 <20190829151320.GC27650@elm>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20190829151320.GC27650@elm>
User-Agent: Mutt/1.12.1 (2019-06-15)
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Thu, Aug 29, 2019 at 10:13:20AM -0500, Tyler Hicks wrote:
> Hello, Sasha!
> 
> On 2019-08-29 06:49:51, Sasha Levin wrote:
> > From: Tyler Hicks <tyhicks@canonical.com>
> > 
> > [ Upstream commit 60d4885710836595192c42d3e04b27551d30ec91 ]
> > 
> > Restore the behavior of locking mmap_sem for reading in
> > binder_alloc_free_page(), as was first done in commit 3013bf62b67a
> > ("binder: reduce mmap_sem write-side lock"). That change was
> > inadvertently reverted by commit 5cec2d2e5839 ("binder: fix race between
> > munmap() and direct reclaim").
> > 
> > In addition, change the name of the label for the error path to
> > accurately reflect that we're taking the lock for reading.
> > 
> > Backporting note: This fix is only needed when *both* of the commits
> > mentioned above are applied. That's an unlikely situation since they
> > both landed during the development of v5.1 but only one of them is
> > targeted for stable.
> 
> This patch isn't meant to be applied to 4.19 since commit 3013bf62b67a
> ("binder: reduce mmap_sem write-side lock") was never brought back to
> 4.19.
> 
> Tyler
> 
> > 
> > Fixes: 5cec2d2e5839 ("binder: fix race between munmap() and direct reclaim")

But this commit is in 4.19.49

thanks,

greg k-h