Hi Ville & Daniel,
Am 25.03.22 um 16:28 schrieb Christian König:
Am 25.03.22 um 16:25 schrieb Ville Syrjälä:
On Fri, Mar 11, 2022 at 12:02:43PM +0100, Christian König wrote:
Add a general purpose helper to deep dive into
dma_fence_chain/dma_fence_array
structures and iterate over all the fences in them.
This is useful when we need to flatten out all fences in those
structures.
Signed-off-by: Christian König <christian.koenig@xxxxxxx>
One of the dma-buf patches took down Intel CI. Looks like every
machine oopses in some sync_file thing now:
<1>[ 260.470008] BUG: kernel NULL pointer dereference, address:
0000000000000010
<1>[ 260.470020] #PF: supervisor read access in kernel mode
<1>[ 260.470025] #PF: error_code(0x0000) - not-present page
<6>[ 260.470030] PGD 0 P4D 0
<4>[ 260.470035] Oops: 0000 [#1] PREEMPT SMP NOPTI
<4>[ 260.470040] CPU: 0 PID: 5306 Comm: core_hotunplug Not tainted
5.17.0-CI-CI_DRM_11405+ #1
<4>[ 260.470049] Hardware name: Intel Corporation Jasper Lake Client
Platform/Jasperlake DDR4 SODIMM RVP, BIOS
JSLSFWI1.R00.2385.D02.2010160831 10/16/2020
<4>[ 260.470058] RIP: 0010:dma_fence_array_first+0x19/0x20
I've looked into this and the root cause seems to be that the new code
doesn't handle dma_fence_arrays with zero elements.
That is rather easy to fix, but a dma_fence_array with zero number of
elements is most likely a bug because under the wrong circumstances it
can create a dma_fence instance which will never signal.
I've send out a patch on Frinday ([PATCH] dma-buf: WIP
dma_fence_array_first fix) which avoids the crash and prints a warning
if anybody tries to create a dma_fence_array with zero length.
Can you test this?
Thanks in advance,
Christian.
