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From: Takashi Iwai <tiwai@suse.de>
To: dri-devel@lists.freedesktop.org
Cc: linux-kernel@vger.kernel.org
Subject: Atomicity in KMS panic notifier
Date: Mon, 05 May 2014 15:02:09 +0200	[thread overview]
Message-ID: <s5htx94fkfi.wl%tiwai@suse.de> (raw)

Hi,

while debugging a few reported bugs, I noticed that
drm_fb_helper_force_kernel_mode() that is called in the KMS panic
notifier isn't really atomic-safe.  It invokes crtc's set_config(),
and all implementations seem to involve with page allocations (kmalloc
with GFP_KERNEL, via some ttm ops, etc).  I've actually seen the Oops
with cirrus KMS during panic due to this.

Does anyone have an idea to fix this?  I thought of re-using
drm_fb_helper_debug_enter(), but this won't work with many drivers
that don't have crtc->mode_set_base_atomic(), either (yeah, this is
another bug).


thanks,

Takashi

             reply	other threads:[~2014-05-05 13:02 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-05-05 13:02 Takashi Iwai [this message]
2014-05-05 14:29 ` Daniel Vetter
2014-05-05 14:48   ` Takashi Iwai
2014-05-05 14:52     ` Daniel Vetter
2014-05-05 15:04       ` Takashi Iwai
2014-05-06 13:27       ` Takashi Iwai
2014-05-06 13:32         ` David Herrmann
2014-05-06 13:38           ` Takashi Iwai
2014-05-06 13:53             ` David Herrmann
2014-05-06 14:07               ` Takashi Iwai
2014-05-07 16:15   ` One Thousand Gnomes

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