From: Linus Torvalds <torvalds@linux-foundation.org>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Hugh Dickins <hughd@google.com>,
Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>,
Matt Roper <matthew.d.roper@intel.com>,
Lucas De Marchi <lucas.demarchi@intel.com>,
Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>,
Caz Yokoyama <caz.yokoyama@intel.com>,
LKML <linux-kernel@vger.kernel.org>,
Jani Nikula <jani.nikula@linux.intel.com>,
Matthew Brost <matthew.brost@intel.com>,
intel-gfx <intel-gfx@lists.freedesktop.org>,
dri-devel <dri-devel@lists.freedesktop.org>
Subject: Re: [BUG 5.15-rc3] kernel BUG at drivers/gpu/drm/i915/i915_sw_fence.c:245!
Date: Sat, 2 Oct 2021 09:49:41 -0700 [thread overview]
Message-ID: <CAHk-=whJsD3RaqpmAMv7yjpnQqrEuXvibXZZDY7f-nzO+PvULg@mail.gmail.com> (raw)
In-Reply-To: <20211002081750.7eec92dd@oasis.local.home>
On Sat, Oct 2, 2021 at 5:17 AM Steven Rostedt <rostedt@goodmis.org> wrote:
>
> On Sat, 2 Oct 2021 03:17:29 -0700 (PDT)
> Hugh Dickins <hughd@google.com> 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
mistake.
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.
Linus
WARNING: multiple messages have this Message-ID (diff)
From: Linus Torvalds <torvalds@linux-foundation.org>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Hugh Dickins <hughd@google.com>,
Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>,
Matt Roper <matthew.d.roper@intel.com>,
Lucas De Marchi <lucas.demarchi@intel.com>,
Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>,
Caz Yokoyama <caz.yokoyama@intel.com>,
LKML <linux-kernel@vger.kernel.org>,
Jani Nikula <jani.nikula@linux.intel.com>,
Matthew Brost <matthew.brost@intel.com>,
intel-gfx <intel-gfx@lists.freedesktop.org>,
dri-devel <dri-devel@lists.freedesktop.org>
Subject: Re: [Intel-gfx] [BUG 5.15-rc3] kernel BUG at drivers/gpu/drm/i915/i915_sw_fence.c:245!
Date: Sat, 2 Oct 2021 09:49:41 -0700 [thread overview]
Message-ID: <CAHk-=whJsD3RaqpmAMv7yjpnQqrEuXvibXZZDY7f-nzO+PvULg@mail.gmail.com> (raw)
In-Reply-To: <20211002081750.7eec92dd@oasis.local.home>
On Sat, Oct 2, 2021 at 5:17 AM Steven Rostedt <rostedt@goodmis.org> wrote:
>
> On Sat, 2 Oct 2021 03:17:29 -0700 (PDT)
> Hugh Dickins <hughd@google.com> 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
mistake.
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.
Linus
next prev parent reply other threads:[~2021-10-02 16:50 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-02 6:02 [BUG 5.15-rc3] kernel BUG at drivers/gpu/drm/i915/i915_sw_fence.c:245! Steven Rostedt
2021-10-02 6:02 ` [Intel-gfx] " Steven Rostedt
2021-10-02 10:17 ` Hugh Dickins
2021-10-02 10:17 ` Hugh Dickins
2021-10-02 10:17 ` [Intel-gfx] " Hugh Dickins
2021-10-02 12:17 ` Steven Rostedt
2021-10-02 12:17 ` [Intel-gfx] " Steven Rostedt
2021-10-02 16:49 ` Linus Torvalds [this message]
2021-10-02 16:49 ` Linus Torvalds
2021-10-02 16:49 ` [Intel-gfx] " Linus Torvalds
2021-10-02 17:10 ` Hugh Dickins
2021-10-02 17:10 ` [Intel-gfx] " Hugh Dickins
2021-10-02 17:10 ` Hugh Dickins
2021-10-04 7:39 ` Jani Nikula
2021-10-04 7:39 ` [Intel-gfx] " Jani Nikula
2021-10-02 10:52 ` [Intel-gfx] ✗ Fi.CI.CHECKPATCH: warning for " Patchwork
2021-10-02 11:26 ` [Intel-gfx] ✓ Fi.CI.BAT: success " Patchwork
2021-10-02 12:46 ` [Intel-gfx] ✓ Fi.CI.IGT: " Patchwork
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to='CAHk-=whJsD3RaqpmAMv7yjpnQqrEuXvibXZZDY7f-nzO+PvULg@mail.gmail.com' \
--to=torvalds@linux-foundation.org \
--cc=caz.yokoyama@intel.com \
--cc=daniele.ceraolospurio@intel.com \
--cc=dri-devel@lists.freedesktop.org \
--cc=hughd@google.com \
--cc=intel-gfx@lists.freedesktop.org \
--cc=jani.nikula@linux.intel.com \
--cc=linux-kernel@vger.kernel.org \
--cc=lucas.demarchi@intel.com \
--cc=matthew.brost@intel.com \
--cc=matthew.d.roper@intel.com \
--cc=rostedt@goodmis.org \
--cc=tvrtko.ursulin@linux.intel.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.