lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  PHC 
Open Source and information security mailing list archives
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date:   Sat, 2 Oct 2021 09:49:41 -0700
From:   Linus Torvalds <>
To:     Steven Rostedt <>
Cc:     Hugh Dickins <>,
        Daniele Ceraolo Spurio <>,
        Matt Roper <>,
        Lucas De Marchi <>,
        Tvrtko Ursulin <>,
        Caz Yokoyama <>,
        LKML <>,
        Jani Nikula <>,
        Matthew Brost <>,
        intel-gfx <>,
        dri-devel <>
Subject: Re: [BUG 5.15-rc3] kernel BUG at drivers/gpu/drm/i915/i915_sw_fence.c:245!

On Sat, Oct 2, 2021 at 5:17 AM Steven Rostedt <> wrote:
> On Sat, 2 Oct 2021 03:17:29 -0700 (PDT)
> Hugh Dickins <> wrote:
> > Yes (though bisection doesn't work right on this one): the fix
> Interesting, as it appeared to be very reliable. But I didn't do the
> "try before / after" on the patch.

Well, even the before/after might well have worked, since the problem
depended on how that sw_fence_dummy_notify() function ended up
aligned. So random unrelated changes could re-align it just by

Patch applied directly.

I'd also like to point out how that BUG_ON() actually made things
worse, and made this harder to debug. If it had been a WARN_ON_ONCE(),
this would presumably not even have needed bisecting, it would have
been obvious.

BUG_ON() really is pretty much *always* the wrong thing to do. It
onl;y results in problems being harder to see because you end up with
a dead machine and the message is often hidden.


Powered by blists - more mailing lists