linux-kernel - Re: [PATCH] staging: android: ashmem: Shrink directly through shmem

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Message-ID: <20180716094851.GA31480@kroah.com>
Date:   Mon, 16 Jul 2018 11:48:51 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     Joel Fernandes <joel@...lfernandes.org>
Cc:     linux-kernel@...r.kernel.org, devel@...verdev.osuosl.org,
        Todd Kjos <tkjos@...roid.com>,
        Jeff Vander Stoep <jeffv@...gle.com>,
        Arve H <arve@...roid.com>, Martijn Coenen <maco@...roid.com>,
        Tobias Lindskog <tobias.lindskog@...ymobile.com>,
        kernel-team@...roid.com
Subject: Re: [PATCH] staging: android: ashmem: Shrink directly through
 shmem_fallocate

On Fri, Jul 06, 2018 at 02:44:16PM -0700, Joel Fernandes wrote:
> From: Tobias Lindskog <tobias.lindskog@...ymobile.com>
> 
> When ashmem_shrink is called from direct reclaim on a user thread, a
> call to do_fallocate will check for permissions against the security
> policy of that user thread.  It can thus fail by chance if called on a
> thread that isn't permitted to modify the relevant ashmem areas.
> 
> Because we know that we have a shmem file underneath, call the shmem
> implementation of fallocate directly instead of going through the
> user-space interface for fallocate.
> 
> Bug: 21951515

What does this "Bug:" line mean to any of us?  :)

I'll go delete it, and I fixed up the subject to have 'staging: android'
in it as well.  Please do that next time.

thanks,

greg k-h