bisecting fixing commit since 54b4fa6d39551639cb10664f6ac78b01993a1d7e building syzkaller on c8d1cc20df5ca5d9ea437054720fa3cfdfa1f578 testing commit 54b4fa6d39551639cb10664f6ac78b01993a1d7e with gcc (GCC) 8.1.0 kernel signature: b683505277a37898fa17c68e37e487b848b6c8f5194278a94e7f037c12d03977 all runs: crashed: kernel BUG at drivers/dma-buf/dma-buf.c:LINE! testing current HEAD 20b3a3dfdf6c55b50bbdc8e231a3dbf6bf965dc7 testing commit 20b3a3dfdf6c55b50bbdc8e231a3dbf6bf965dc7 with gcc (GCC) 8.1.0 kernel signature: 774ec39eb11e5650884c179562f1f243e0d919cd2f8b23e576bcb550db087c3c all runs: crashed: kernel BUG at drivers/dma-buf/dma-buf.c:LINE! revisions tested: 2, total time: 26m24.848113467s (build: 19m18.622928775s, test: 6m7.348761775s) the crash still happens on HEAD commit msg: Linux 4.19.134 crash: kernel BUG at drivers/dma-buf/dma-buf.c:LINE! 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: 8558 Comm: syz-executor.0 Not tainted 4.19.134-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 cd 7b 6f fd 48 89 df e8 35 c2 a8 fd 31 c0 48 83 c4 10 5b 41 5c 41 5d 41 5e 41 5f 5d c3 <0f> 0b e8 5d 66 67 fd 48 8d bb 38 02 00 00 48 b8 00 00 00 00 00 fc RSP: 0018:ffff888081c8fdd0 EFLAGS: 00010202 RAX: 0000000000000000 RBX: ffff88809c3fe4c0 RCX: 0000000000000004 RDX: 1ffff1101387fcc7 RSI: 0000000000000000 RDI: ffff88809c3fe638 RBP: ffff888081c8fe08 R08: 0000000000000000 R09: 0000000000000000 R10: ffff888081c8fe18 R11: ffff8880a6a1c4f0 R12: ffff8880a0db2b3c R13: ffff8880a6a1c4f0 R14: ffffffff878475a0 R15: ffff88821a50c020 FS: 0000000001202940(0000) GS:ffff8880aea00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fbac39ec008 CR3: 00000000a896e000 CR4: 00000000001406f0 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: 0033:0x4163e1 Code: 75 14 b8 03 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 04 1b 00 00 c3 48 83 ec 08 e8 0a fc ff ff 48 89 04 24 b8 03 00 00 00 0f 05 <48> 8b 3c 24 48 89 c2 e8 53 fc ff ff 48 89 d0 48 83 c4 08 48 3d 01 RSP: 002b:00007ffe7fd56aa0 EFLAGS: 00000293 ORIG_RAX: 0000000000000003 RAX: 0000000000000000 RBX: 0000000000000008 RCX: 00000000004163e1 RDX: 0000000000000000 RSI: 0000000000000081 RDI: 0000000000000007 RBP: 0000000000000000 R08: 0000000000000000 R09: 01ffffffffffffff R10: 00000000007708c0 R11: 0000000000000293 R12: 000000000076bf00 R13: 00000000007708d0 R14: 0000000000000000 R15: 000000000076bf0c Modules linked in: ---[ end trace 5bc8de989ac158e8 ]--- 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 cd 7b 6f fd 48 89 df e8 35 c2 a8 fd 31 c0 48 83 c4 10 5b 41 5c 41 5d 41 5e 41 5f 5d c3 <0f> 0b e8 5d 66 67 fd 48 8d bb 38 02 00 00 48 b8 00 00 00 00 00 fc RSP: 0018:ffff888081c8fdd0 EFLAGS: 00010202 RAX: 0000000000000000 RBX: ffff88809c3fe4c0 RCX: 0000000000000004 RDX: 1ffff1101387fcc7 RSI: 0000000000000000 RDI: ffff88809c3fe638 RBP: ffff888081c8fe08 R08: 0000000000000000 R09: 0000000000000000 R10: ffff888081c8fe18 R11: ffff8880a6a1c4f0 R12: ffff8880a0db2b3c R13: ffff8880a6a1c4f0 R14: ffffffff878475a0 R15: ffff88821a50c020 FS: 0000000001202940(0000) GS:ffff8880aea00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fbac39ec008 CR3: 00000000a896e000 CR4: 00000000001406f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400