On Die, 2010-11-09 at 11:37 +0100, Markus Trippelsdorf wrote: > On Tue, Nov 09, 2010 at 11:32:57AM +0100, Michel DÃnzer wrote: > > On Die, 2010-11-09 at 11:07 +0100, Thomas Hellstrom wrote: > > > On 11/09/2010 10:53 AM, Thomas Hellstrom wrote: > > > > On 11/09/2010 10:29 AM, Markus Trippelsdorf wrote: > > > >> OK I've found the buggy commit by bisection: > > > >> > > > >> e376573f7267390f4e1bdc552564b6fb913bce76 is the first bad commit > > > >> commit e376573f7267390f4e1bdc552564b6fb913bce76 > > > >> Author: Michel DÃnzer<daenzer@xxxxxxxxxx> > > > >> Date: Thu Jul 8 12:43:28 2010 +1000 > > > >> > > > >> drm/radeon: fall back to GTT if bo creation/validation in VRAM > > > >> fails. > > > >> > > > >> This fixes a problem where on low VRAM cards we'd run out of > > > >> space for validation. > > > >> > > > >> [airlied: Tested on my M7, Thinkpad T42, compiz works with no > > > >> problems.] > > > >> > > > >> Signed-off-by: Michel DÃnzer<daenzer@xxxxxxxxxx> > > > >> Cc: stable@xxxxxxxxxx > > > >> Signed-off-by: Dave Airlie<airlied@xxxxxxxxxx> > > > >> > > > >> Please note that this is an old commit from 2.6.36-rc. When I revert > > > >> it the > > > >> kernel no longer crashes. Instead I see the following in my dmesg: > > > >> > > > > > > > > Hmm, so this sounds like something in the Radeon eviction error path > > > > is causing corruption. > > > > I had a similar problem with vmwgfx, when I tried to unref a BO > > > > _after_ ttm_bo_init() failed. > > > > ttm_bo_init() is really supposed to call unref itself for various > > > > reasons, so calling unref() or kfree() after a failed ttm_bo_init() > > > > will cause corruption. > > > > > > > > In any case, the error below also suggests something is a bit fragile > > > > in the Radeon driver: > > > > > > > > First, an accelerated eviction may fail, like in the message below, > > > > but then there must always be a backup plan, like unaccelerated > > > > eviction to system. On BO creation, there are a number of placement > > > > strategies, but if all else fails, it should be possible to initially > > > > place the BO in system memory. > > > > > > > > Second, If bo validation fails during a command submission, due to > > > > insufficient VRAM / TT, then the driver should retry the complete > > > > validation cycle after first blocking all other validators and then > > > > evicting everything not pinned, to avoid failures due to fragmentation. > > > > > > > > /Thomas > > > > > > > > > > Indeed, it seems like the commit you mention just retries ttm_bo_init() > > > after it previously failed. At that point the bo has been destroyed, so > > > that is probably what's causing the BUG you are seeing. > > > > > > Admittedly, ttm_bo_init() calling unref on failure is not properly > > > documented in the function description. The reason for doing so is to > > > have a single path for freeing all BO resources already allocated on the > > > point of failure. > > > > Does the patch below fix the problem? > > Yes, indeed. I was just about to send the same patch to the list. > > Thanks. Thank you for testing / confirming the fix, and to Thomas for the analysis of the problem. I've submitted the fix to Dave with your Tested-by: added. -- Earthling Michel DÃnzer | http://www.vmware.com Libre software enthusiast | Debian, X and DRI developer _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/dri-devel
