From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jan Schmidt Subject: Re: WARNING: at fs/btrfs/extent-tree.c:4754 followed by BUG: unable to handle kernel NULL pointer dereference at (null) Date: Thu, 08 Dec 2011 17:03:55 +0100 Message-ID: <4EE0DFEB.2000904@jan-o-sch.net> References: Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Cc: linux-btrfs@vger.kernel.org To: Kai Krakow Return-path: In-Reply-To: List-ID: On 07.12.2011 21:40, Kai Krakow wrote: > Scrubbing reports 1 uncorrectable error. I have this error since my system > froze due to some xorg graphic driver instability (was trying out SNA > acceleration for sandybridge). > > The problematic file seems to be in /usr/portage but scrubbing doesn't tell > me the filename (I was under the impression 3.2.x adds a patch which should > report filenames). It should. Did you take a look at dmesg output after scrubbing? If it doesn't contain a hint on the file or block, please paste what you get. > Everytime I run "emerge" (it is a gentoo system) my > screen goes black after a few seconds and I can only revert to using ssh. > > Problem is: As soon as this happens, some filesystem accesses block the > process in disk state, it cannot be killed. This initiates some feedback > loop: From now on any other process trying to access the FS freezes. I can > only reisub now. It seems to be fine if data comes from cache instead from > disk. Please try to grab sysrq+w output in this state. -Jan