linux-kernel - Re: [PATCH 1/2] zram: fix crashes due to use of cpu hotplug multistate

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Message-ID: <20210407153031.m4gg3rsgwlr432ba@treble>
Date:   Wed, 7 Apr 2021 10:30:31 -0500
From:   Josh Poimboeuf <jpoimboe@...hat.com>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     Miroslav Benes <mbenes@...e.cz>,
        Greg KH <gregkh@...uxfoundation.org>,
        Luis Chamberlain <mcgrof@...nel.org>, mbenes@...e.com,
        Minchan Kim <minchan@...nel.org>, keescook@...omium.org,
        dhowells@...hat.com, hch@...radead.org, ngupta@...are.org,
        sergey.senozhatsky.work@...il.com, axboe@...nel.dk,
        linux-block@...r.kernel.org, linux-kernel@...r.kernel.org,
        live-patching@...r.kernel.org, Jessica Yu <jeyu@...nel.org>
Subject: Re: [PATCH 1/2] zram: fix crashes due to use of cpu hotplug
 multistate

On Wed, Apr 07, 2021 at 04:09:44PM +0200, Peter Zijlstra wrote:
> On Tue, Apr 06, 2021 at 10:54:23AM -0500, Josh Poimboeuf wrote:
> 
> > Same for Red Hat.  Unloading livepatch modules seems to work fine, but
> > isn't officially supported.
> > 
> > That said, if rmmod is just considered a development aid, and we're
> > going to be ignoring bugs, we should make it official with a new
> > TAINT_RMMOD.
> 
> Another option would be to have live-patch modules leak a module
> reference by default, except when some debug sysctl is set or something.
> Then only those LP modules loaded while the sysctl is set to 'YOLO' can
> be unloaded.

The issue is broader than just live patching.

My suggestion was that if we aren't going to fix bugs in kernel module
unloading, then unloading modules shouldn't be supported, and should
taint the kernel.

-- 
Josh