linux-kernel - Re: [RFC PATCH 1/3] Revert "binder_alloc: add missing mmap

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Date:   Wed, 26 Apr 2023 21:22:13 +0000
From:   Carlos Llamas <cmllamas@...gle.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Arve Hjønnevåg <arve@...roid.com>,
        Todd Kjos <tkjos@...roid.com>,
        Martijn Coenen <maco@...roid.com>,
        Joel Fernandes <joel@...lfernandes.org>,
        Christian Brauner <brauner@...nel.org>,
        Suren Baghdasaryan <surenb@...gle.com>,
        linux-kernel@...r.kernel.org, kernel-team@...roid.com,
        Liam Howlett <liam.howlett@...cle.com>
Subject: Re: [RFC PATCH 1/3] Revert "binder_alloc: add missing mmap_lock
 calls when using the VMA"

On Tue, Apr 25, 2023 at 07:19:20AM +0200, Greg Kroah-Hartman wrote:
> On Mon, Apr 24, 2023 at 08:55:46PM +0000, Carlos Llamas wrote:
> > This reverts commit 44e602b4e52f70f04620bbbf4fe46ecb40170bde.
> > 
> > This caused a performance regression particularly when pages are getting
> > reclaimed. We don't need to acquire the mmap_lock to determine when the
> > binder buffer has been fully initialized. A subsequent patch will bring
> > back the lockless approach for this.
> > 
> > [cmllamas: resolved trivial conflicts with renaming of alloc->mm]
> > 
> > Cc: Liam Howlett <liam.howlett@...cle.com>
> > Cc: Suren Baghdasaryan <surenb@...gle.com>
> > Signed-off-by: Carlos Llamas <cmllamas@...gle.com>
> > ---
> >  drivers/android/binder_alloc.c | 31 ++++++++++---------------------
> >  1 file changed, 10 insertions(+), 21 deletions(-)
> 
> Why is this series "RFC"?  What needs to be done to be able to submit it
> as a real patch series?

No real reason. Just wanted to get feedback from the mm folks first.
I'll go ahead and submit the v1.

> 
> Also, as the commits you are reverting are in older kernels, please
> properly cc: stable in the signed-off-by area, and add a fixes: tag for
> the commit you are reverting when you resend these as a real series.

Sounds good, thanks!