bisecting fixing commit since 54b4fa6d39551639cb10664f6ac78b01993a1d7e building syzkaller on c8d1cc20df5ca5d9ea437054720fa3cfdfa1f578 testing commit 54b4fa6d39551639cb10664f6ac78b01993a1d7e compiler: gcc version 8.4.1 20210217 (GCC) kernel signature: 78935e6ac14a736ee9d2aeb984370c93b76e3bf2bd0c495055893a5f14dd2bcf all runs: crashed: kernel BUG in dma_buf_release testing current HEAD 4938296e03bd227e5020d63d418956fe52baf97c testing commit 4938296e03bd227e5020d63d418956fe52baf97c compiler: gcc version 8.4.1 20210217 (GCC) kernel signature: dc8406639239ba20a569e52897b7412a15a5637e8f1a60652311b2ab7e166296 all runs: crashed: kernel BUG in dma_buf_release revisions tested: 2, total time: 28m48.966673744s (build: 21m57.194912384s, test: 6m23.911411155s) the crash still happens on HEAD commit msg: Linux 4.19.198 crash: kernel BUG in dma_buf_release IPv6: ADDRCONF(NETDEV_UP): batadv_slave_1: link is not ready batman_adv: batadv0: Interface activated: batadv_slave_1 IPv6: ADDRCONF(NETDEV_CHANGE): batadv_slave_1: link becomes ready IPv6: ADDRCONF(NETDEV_CHANGE): veth1_to_batadv: link becomes ready ------------[ cut here ]------------ kernel BUG at drivers/dma-buf/dma-buf.c:68! invalid opcode: 0000 [#1] PREEMPT SMP KASAN CPU: 0 PID: 8638 Comm: syz-executor.5 Not tainted 4.19.198-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:dma_buf_release+0x2ec/0x570 drivers/dma-buf/dma-buf.c:68 Code: 85 36 02 00 00 48 8b bb c0 00 00 00 e8 9d 2a 76 fd 48 89 df e8 f5 35 af fd 31 c0 48 83 c4 10 5b 41 5c 41 5d 41 5e 41 5f 5d c3 <0f> 0b e8 dd 5f 6e fd 48 8d bb 38 02 00 00 48 b8 00 00 00 00 00 fc RSP: 0018:ffff8881dc88fdd0 EFLAGS: 00010202 RAX: 0000000000000000 RBX: ffff8881dc7fcd80 RCX: 0000000000000004 RDX: 1ffff1103b8ff9df RSI: 0000000000000000 RDI: ffff8881dc7fcef8 RBP: ffff8881dc88fe08 R08: 0000000000000000 R09: 0000000000000000 R10: ffff8881dc88fe18 R11: ffff8881f13bb0c0 R12: ffff8881d65900bc R13: ffff8881f13bb0c0 R14: ffffffff87849ce0 R15: ffff8881f57c0420 FS: 00000000014ea400(0000) GS:ffff8881f6800000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fed62e04718 CR3: 00000001f3df6002 CR4: 00000000001606f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: __fput+0x249/0x7f0 fs/file_table.c:278 ____fput+0x9/0x10 fs/file_table.c:309 task_work_run+0x108/0x180 kernel/task_work.c:113 tracehook_notify_resume include/linux/tracehook.h:193 [inline] exit_to_usermode_loop+0x1a9/0x200 arch/x86/entry/common.c:167 prepare_exit_to_usermode arch/x86/entry/common.c:198 [inline] syscall_return_slowpath arch/x86/entry/common.c:271 [inline] do_syscall_64+0x413/0x4e0 arch/x86/entry/common.c:296 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x41741b Code: 0f 05 48 3d 00 f0 ff ff 77 45 c3 0f 1f 40 00 48 83 ec 18 89 7c 24 0c e8 63 fc ff ff 8b 7c 24 0c 41 89 c0 b8 03 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 35 44 89 c7 89 44 24 0c e8 a1 fc ff ff 8b 44 RSP: 002b:00007ffe2e7b1dd0 EFLAGS: 00000293 ORIG_RAX: 0000000000000003 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 000000000041741b RDX: ffffffffffffffbc RSI: 00000000005408c8 RDI: 0000000000000007 RBP: 0000000000000008 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000538070 R11: 0000000000000293 R12: 00000000005408c8 R13: 000000000053bf00 R14: 00007ffe2e7b1ed0 R15: 000000000053bf00 Modules linked in: ---[ end trace c5203242e706f190 ]--- RIP: 0010:dma_buf_release+0x2ec/0x570 drivers/dma-buf/dma-buf.c:68 Code: 85 36 02 00 00 48 8b bb c0 00 00 00 e8 9d 2a 76 fd 48 89 df e8 f5 35 af fd 31 c0 48 83 c4 10 5b 41 5c 41 5d 41 5e 41 5f 5d c3 <0f> 0b e8 dd 5f 6e fd 48 8d bb 38 02 00 00 48 b8 00 00 00 00 00 fc RSP: 0018:ffff8881dc88fdd0 EFLAGS: 00010202 RAX: 0000000000000000 RBX: ffff8881dc7fcd80 RCX: 0000000000000004 RDX: 1ffff1103b8ff9df RSI: 0000000000000000 RDI: ffff8881dc7fcef8 RBP: ffff8881dc88fe08 R08: 0000000000000000 R09: 0000000000000000 R10: ffff8881dc88fe18 R11: ffff8881f13bb0c0 R12: ffff8881d65900bc R13: ffff8881f13bb0c0 R14: ffffffff87849ce0 R15: ffff8881f57c0420 FS: 00000000014ea400(0000) GS:ffff8881f6900000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fb67621c020 CR3: 00000001f3df6004 CR4: 00000000001606e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400