On 3/4/26 17:37, Sebastian Brzezinka wrote: > On Wed Mar 4, 2026 at 5:28 PM CET, Jani Nikula wrote: >> On Tue, 03 Mar 2026, Christian König <[email protected]> wrote: >>> On 3/3/26 13:26, Sebastian Brzezinka wrote: >>>> Since commit 541c8f2468b9 ("dma-buf: detach fence ops on signal v3"), >>>> fence->ops may be set to NULL via RCU when a fence signals and has no >>>> release/wait ops. ttm_bo_flush_all_fences() was not updated to handle >>>> this and directly dereferences fence->ops->signaled, leading to a NULL >>>> pointer dereference crash: >>>> >>>> ``` >>>> BUG: kernel NULL pointer dereference, address: 0000000000000018 >>>> RIP: 0010:ttm_bo_release+0x1bc/0x330 [ttm] >>>> ``` >>>> >>>> Since dma_fence_enable_sw_signaling() already handles the signaled case >>>> internally (it checks DMA_FENCE_FLAG_SIGNALED_BIT before doing anything), >>>> the ops->signaled pre-check is redundant. Simply remove it and call >>>> dma_fence_enable_sw_signaling() unconditionally for each fence. >>>> >>>> Closes: https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/15759 >>>> Fixes: 541c8f2468b9 ("dma-buf: detach fence ops on signal v3") >>>> Cc: Christian König <[email protected]> >>>> Signed-off-by: Sebastian Brzezinka <[email protected]> >>> >>> Reviewed-by: Christian König <[email protected]> >>> >>> Going to push that to drm-misc-next now. >> >> Christian, did you forget to push or is there still something missing >> here?
AMDs mail servers currently mangle all mails to HTML mails (again!). So I tried to pick this one up from the dri-devel patchwork just to find that dri-devel was never CCed. But I couldn't find time to complain about that yesterday. I've just re-created the patch by copy&paste and pushed it to drm-misc-next. >> >> Sebastian, for future reference, drm/ttm patches need to be sent to the >> dri-devel mailing list. I bounced the patch there now. See MAINTAINERS >> and/or use scripts/get_maintainer.pl to see where you need to send the >> patches. The intel-gfx list is sufficient for i915 changes only. +1 Regards, Christian. >> >> BR, >> Jani. > Thanks for the guidance and for bouncing the patch to the correct list. >
