linux-kernel - Re: [PATCH] mm/slub: Add taint after the errors are printed

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Message-ID: <YMp3htJJkyVZJglK@optiplex-fbsd>
Date:   Wed, 16 Jun 2021 18:13:26 -0400
From:   Rafael Aquini <aquini@...hat.com>
To:     Vlastimil Babka <vbabka@...e.cz>
Cc:     Georgi Djakov <quic_c_gdjako@...cinc.com>,
        akpm@...ux-foundation.org, iamjoonsoo.kim@....com,
        rientjes@...gle.com, penberg@...nel.org, cl@...ux.com,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org, djakov@...nel.org
Subject: Re: [PATCH] mm/slub: Add taint after the errors are printed

On Wed, Jun 16, 2021 at 06:34:41PM +0200, Vlastimil Babka wrote:
> On 6/16/21 6:25 PM, Georgi Djakov wrote:
> > When running the kernel with panic_on_taint, the usual slub debug error
> > messages are not being printed when object corruption happens. That's
> > because we panic in add_taint(), which is called before printing the
> > additional information. This is a bit unfortunate as the error messages
> > are actually very useful, especially before a panic. Let's fix this by
> > moving add_taint() after the errors are printed on the console.
> > 
> > Signed-off-by: Georgi Djakov <quic_c_gdjako@...cinc.com>
> 
> Makes sense.
> 
> While at it, I wonder if we should use LOCKDEP_STILL_OK instead of
> LOCKDEP_NOW_UNRELIABLE. Isn't it too pessimistic to assume that some slab's
> memory corruption hit some lock state?
>

Given there is noted corruption I don't think it's safe to assume otherwise.