Re: [PATCH] module: Add CONFIG_MODULE_LOAD_IN_SEQUENCE option

From: Joey Jiao <quic_jiangenj@quicinc.com>
To: Luis Chamberlain <mcgrof@kernel.org>
Cc: "linux-modules@vger.kernel.org" <linux-modules@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] module: Add CONFIG_MODULE_LOAD_IN_SEQUENCE option
Date: Wed, 11 Oct 2023 11:41:56 +0530	[thread overview]
Message-ID: <20231011061156.GA1625@hu-jiangenj-sha.qualcomm.com> (raw)
In-Reply-To: <ZSYGmQhlGKmYXENG@bombadil.infradead.org>

Thanks Luis, will recheck these two points.

On Tue, Oct 10, 2023 at 07:21:13PM -0700, Luis Chamberlain wrote:
> Please find a good email client to reply to patches.
> 
> On Wed, Oct 11, 2023 at 01:57:58AM +0000, Joey Jiao (QUIC) wrote:
> > Hi Luis,
> > 
> > > How is ignoring an error ensuring ordering?
> > The change is just to disable the schedule_work.
> 
> That's different and can be made clearer. Try:
> 
> if (!IS_ENABLED(CONFIG_FOO))
> 	schedule_stuff
> 
> > > Why are you making this only now be called with this new kconfig option?
> > This sequence loading is especially helpful for syzkaller coverage decoding.
> > When kaslr is disabled, address inside core kernel is fixed, so syzkaller can always get right function/line number from addr2line.
> > But module address keeps change across rebooting, in first booting, it might be loaded at X1, and at X2 after reboot, and at X3 after another reboot.
> > In this way, syzkaller just can't decode correctly for module address. And syzkaller currently uses PC and branch info for coverage guided things.
> > 
> > There was a discussion previously here https://groups.google.com/g/syzkaller/c/1Pnm_BjrZO8/m/WOyAKx8ZAgAJ for modprobe.
> 
> You are missing my point, you are disabling in effect a piece of code
> where it was not before.
> 
>   Luis