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;
MIME-Version: 1.0
References: <157117606853.15019.15459271147790470307.stgit@warthog.procyon.org.uk>
 <157117608708.15019.1998141309054662114.stgit@warthog.procyon.org.uk>
In-Reply-To: <157117608708.15019.1998141309054662114.stgit@warthog.procyon.org.uk>
From:   Linus Torvalds <torvalds@linux-foundation.org>
Date:   Tue, 15 Oct 2019 15:14:10 -0700
Message-ID: <CAHk-=whiz1sHXu8SVZKEC2dup=r5JMrftPtEt6ff9Ea8dyH8yQ@mail.gmail.com>
Subject: Re: [RFC PATCH 02/21] Add a prelocked wake-up
To:     David Howells <dhowells@redhat.com>,
        Tim Chen <tim.c.chen@linux.intel.com>,
        Kan Liang <kan.liang@intel.com>
Cc:     Casey Schaufler <casey@schaufler-ca.com>,
        Stephen Smalley <sds@tycho.nsa.gov>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Nicolas Dichtel <nicolas.dichtel@6wind.com>, raven@themaw.net,
        Christian Brauner <christian@brauner.io>,
        keyrings@vger.kernel.org, linux-usb@vger.kernel.org,
        linux-block <linux-block@vger.kernel.org>,
        LSM List <linux-security-module@vger.kernel.org>,
        linux-fsdevel <linux-fsdevel@vger.kernel.org>,
        Linux API <linux-api@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Content-Type: text/plain; charset="UTF-8"
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Tue, Oct 15, 2019 at 2:48 PM David Howells <dhowells@redhat.com> wrote:
>
> Add a wakeup call for a case whereby the caller already has the waitqueue
> spinlock held.

That naming is crazy.

We already have helper functions like this, and they are just called
"wake_up_locked()".

So the "prelocked" naming is just odd. Make it be
wake_up_interruptible_sync_poll_locked().

The helper function should likely be

  void __wake_up_locked_sync_key(struct wait_queue_head *wq_head,
unsigned int mode, void *key)
  {
        __wake_up_common(wq_head, mode, 1, WF_SYNC, key, NULL);
  }
  EXPORT_SYMBOL_GPL(__wake_up_locked_sync_key);

to match the other naming patterns there.

[ Unrelated ]

Looking at that mess of functions, I also wonder if we should try to
just remove the bookmark code again. It was cute, and it was useful,
but I think the problem with the page lock list may have been fixed by
commit 9a1ea439b16b ("mm: put_and_wait_on_page_locked() while page is
migrated") which avoids the retry condition with
migrate_page_move_mapping().

Tim/Kan? Do you have the problematic load still?

              Linus