On 11/09/2010 10:29 AM, Markus Trippelsdorf wrote:
On Mon, Nov 08, 2010 at 11:29:16PM +0100, Thomas Hellstrom wrote:
On 11/08/2010 09:53 PM, Jerome Glisse wrote:
On Mon, Nov 8, 2010 at 2:02 PM, Markus Trippelsdorf markus@trippelsdorf.de wrote:
On Mon, Nov 08, 2010 at 07:43:02PM +0100, Markus Trippelsdorf wrote:
On Mon, Nov 08, 2010 at 06:07:37PM +0100, Markus Trippelsdorf wrote:
On Mon, Nov 08, 2010 at 06:02:21PM +0100, Markus Trippelsdorf wrote:
> I can trigger a kernel crash on my system by simply loading this png > image with firefox: > http://mediaarchive.cern.ch/MediaArchive/Photo/Public/2010/1011251/1011251_0... > Sorry the above link is wrong, this is the right one (that triggers the crash): http://cdsweb.cern.ch/record/1305179/files/HI-150431-630470-huge.png
I triggered it a few more times and took the attached picture. It points to the BUG() call at drivers/gpu/drm/ttm/ttm_bo.c:1628 . (Sorry for the bad picture quality)
And here the same BUG in plaintext (should be a bit easier to read):
Nov 8 19:28:23 arch kernel: ------------[ cut here ]------------ Nov 8 19:28:23 arch kernel: kernel BUG at drivers/gpu/drm/ttm/ttm_bo.c:1628!
Thomas this bug seems to point to a case where we endup trying adding an entry to same offset in the rb tree for addr_space_mm. After reviewing carefully the locking around the rb tree modification& addr_space_mm i am fairly confident that no race can occur. Would you have any idea on what might go wrong here ? I guess i would ultimately need to dump mm& rb tree state when BUG get trigger to try to understand states of things.
I agree there shouldn't be a race in this case. The locking around these operations is simple and straightforward.
So this IMHO should either be a memory corruption or a bug in the range manager. I've never seen this BUG trigger before. Dumping mm / rb tree contents or bisecting should probably find the culprit.
OK I've found the buggy commit by bisection:
e376573f7267390f4e1bdc552564b6fb913bce76 is the first bad commit commit e376573f7267390f4e1bdc552564b6fb913bce76 Author: Michel Dänzerdaenzer@vmware.com 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 Dänzer<daenzer@vmware.com> Cc: stable@kernel.org Signed-off-by: Dave Airlie<airlied@redhat.com>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
[TTM] Failed to find memory space for buffer 0xffff880113e10e48 eviction. [TTM] No space for ffff880113e10e48 (25650 pages, 102600K, 100M) [TTM] placement[0]=0x00070002 (1) [TTM] has_type: 1 [TTM] use_type: 1 [TTM] flags: 0x0000000A [TTM] gpu_offset: 0xA0000000 [TTM] size: 131072 [TTM] available_caching: 0x00070000 [TTM] default_caching: 0x00010000 [TTM] 0x00000000-0x00000001: 1: used [TTM] 0x00000001-0x00000011: 16: used [TTM] 0x00000011-0x00000111: 256: used [TTM] 0x00000111-0x00000211: 256: used [TTM] 0x00000211-0x00000248: 55: free [TTM] 0x00000248-0x0000024c: 4: used [TTM] 0x0000024c-0x00001976: 5930: free [TTM] 0x00001976-0x000021aa: 2100: used [TTM] 0x000021aa-0x0000285f: 1717: free [TTM] 0x0000285f-0x00002860: 1: used [TTM] 0x00002860-0x00002873: 19: free [TTM] 0x00002873-0x000029b3: 320: used [TTM] 0x000029b3-0x00020000: 120397: free [TTM] total: 131072, used 2954 free 128118 [drm:radeon_cs_ioctl] *ERROR* Failed to parse relocation -12! radeon 0000:01:05.0: object_init failed for (117555200, 0x00000004) [drm:radeon_gem_object_create] *ERROR* Failed to allocate GEM object (117555200, 4, 4096, -12) radeon 0000:01:05.0: object_init failed for (117555200, 0x00000004) [drm:radeon_gem_object_create] *ERROR* Failed to allocate GEM object (117555200, 4, 4096, -12) radeon 0000:01:05.0: object_init failed for (117555200, 0x00000004) [drm:radeon_gem_object_create] *ERROR* Failed to allocate GEM object (117555200, 4, 4096, -12) radeon 0000:01:05.0: object_init failed for (117555200, 0x00000004) [drm:radeon_gem_object_create] *ERROR* Failed to allocate GEM object (117555200, 4, 4096, -12) radeon 0000:01:05.0: object_init failed for (117555200, 0x00000004) ...
And the following in the xorg log buffer:
Failed to alloc memory Failed to allocat: size: : 117555200 bytes alignment : 0 bytes domains : 4 ...