I booted a CONFIG_PREEMPT_NONE=y && CONFIG_SMP=n kernel (linux.git as of 9c982e86dbdb), and hit BUG_ON() at __vmw_cmdbuf_header_free().
---------- static void __vmw_cmdbuf_header_free(struct vmw_cmdbuf_header *header) { struct vmw_cmdbuf_man *man = header->man;
BUG_ON(!spin_is_locked(&man->lock));
if (header->inline_space) { vmw_cmdbuf_header_inline_free(header); return; } (...snipped...) ----------
[ 1.883512] ------------[ cut here ]------------ [ 1.885102] kernel BUG at drivers/gpu/drm/vmwgfx/vmwgfx_cmdbuf.c:250! [ 1.886836] invalid opcode: 0000 [#1] [ 1.888390] Modules linked in: [ 1.889519] CPU: 0 PID: 59 Comm: kworker/0:2 Not tainted 4.4.0-rc7+ #22 [ 1.891125] Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 07/31/2013 [ 1.893404] Workqueue: events vmw_fb_dirty_flush [ 1.894767] task: ffff880036406e00 ti: ffff880079a98000 task.ti: ffff880079a98000 [ 1.896572] RIP: 0010:[<ffffffff8143dad4>] [<ffffffff8143dad4>] __vmw_cmdbuf_header_free.isra.16+0x4/0x10 [ 1.898729] RSP: 0018:ffff880079a9bae8 EFLAGS: 00010246 [ 1.900209] RAX: ffff8800365635c8 RBX: ffff88003654aa80 RCX: ffff8800365635e0 [ 1.901950] RDX: ffff8800365635e0 RSI: 0000000000000003 RDI: 0000000000000246 [ 1.903700] RBP: ffff880079a9bae8 R08: 0000000000000000 R09: 0000000000000000 [ 1.905713] R10: 0000000000000000 R11: 0000000000000000 R12: ffff880079b1c300 [ 1.907498] R13: 0000000000000001 R14: ffff88003654aa98 R15: ffff880036563400 [ 1.909306] FS: 0000000000000000(0000) GS:ffffffff81c23000(0000) knlGS:0000000000000000 [ 1.911147] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 1.912711] CR2: 00007f8e571d8298 CR3: 0000000079b33000 CR4: 00000000001406f0 [ 1.914541] Stack: [ 1.915430] ffff880079a9bb58 ffffffff8143dc78 ffff880036563430 ffff880036563490 [ 1.917350] ffff880036563478 ffff8800365635e0 ffff880036563590 ffff880036563458 [ 1.919311] ffff880036563468 ffff880036563400 ffff880079b1c300 0000000000000008 [ 1.921239] Call Trace: [ 1.922235] [<ffffffff8143dc78>] vmw_cmdbuf_man_process+0xe8/0x220 [ 1.923841] [<ffffffff8143e20f>] __vmw_cmdbuf_cur_flush+0x8f/0xe0 [ 1.925504] [<ffffffff8143ea96>] vmw_cmdbuf_commit+0x96/0xe0 [ 1.927000] [<ffffffff814330c1>] vmw_fifo_commit_flush+0x21/0x40 [ 1.928559] [<ffffffff81433169>] vmw_fifo_send_fence+0x69/0xd0 [ 1.930145] [<ffffffff81426c90>] vmw_execbuf_fence_commands+0x50/0x100 [ 1.931767] [<ffffffff8142b4ab>] vmw_kms_helper_buffer_finish+0x4b/0xe0 [ 1.933442] [<ffffffff8143308e>] ? vmw_fifo_commit+0x1e/0x30 [ 1.935000] [<ffffffff81438139>] vmw_kms_sou_do_dmabuf_dirty+0xe9/0x110 [ 1.936652] [<ffffffff814374c0>] ? vmw_sou_surface_fifo_commit+0xf0/0xf0 [ 1.938408] [<ffffffff81437330>] ? vmw_sou_surface_clip+0x70/0x70 [ 1.939970] [<ffffffff81428b28>] vmw_framebuffer_dmabuf_dirty+0x148/0x1f0 [ 1.941589] [<ffffffff8107c5e9>] ? update_curr+0x99/0xe0 [ 1.943092] [<ffffffff8142df51>] vmw_fb_dirty_flush+0x231/0x290 [ 1.944586] [<ffffffff8106e1fb>] process_one_work+0x11b/0x310 [ 1.946087] [<ffffffff8106e4fe>] worker_thread+0x10e/0x440 [ 1.947586] [<ffffffff8164be9c>] ? __schedule+0x22c/0x590 [ 1.949067] [<ffffffff8106e3f0>] ? process_one_work+0x310/0x310 [ 1.950573] [<ffffffff810730f2>] kthread+0xd2/0xf0 [ 1.951894] [<ffffffff81073020>] ? kthread_worker_fn+0x150/0x150 [ 1.953472] [<ffffffff8164edff>] ret_from_fork+0x3f/0x70 [ 1.954905] [<ffffffff81073020>] ? kthread_worker_fn+0x150/0x150 [ 1.956432] Code: 48 8b 43 f0 c7 00 00 00 00 00 eb e2 be 5b 01 00 00 48 c7 c7 18 81 9a 81 e8 4a d6 c1 ff c6 05 d8 e1 86 00 01 eb da 90 55 48 89 e5 <0f> 0b 66 2e 0f 1f 84 00 00 00 00 00 55 48 89 e5 41 54 53 48 89 [ 1.962434] RIP [<ffffffff8143dad4>] __vmw_cmdbuf_header_free.isra.16+0x4/0x10 [ 1.964217] RSP <ffff880079a9bae8> [ 1.965409] ---[ end trace 6120f678d5112bae ]--- [ 1.966727] Kernel panic - not syncing: Fatal exception in interrupt [ 1.968374] Kernel Offset: disabled [ 1.969467] ---[ end Kernel panic - not syncing: Fatal exception in interrupt