FYI, we noticed the following commit: commit: 24972782d0379cd7e2f1d049f642863223c4416b ("fs: Remove iput_final()") https://git.kernel.org/cgit/linux/kernel/git/peterz/queue.git locking/refcounts in testcase: trinity with following parameters: runtime: 300s test-description: Trinity is a linux system call fuzz tester. test-url: http://codemonkey.org.uk/projects/trinity/ on test machine: qemu-system-i386 -enable-kvm -smp 2 -m 320M caused below changes (please refer to attached dmesg/kmsg for entire log/backtrace): +------------------------------------------+------------+------------+ | | 9a4111a75d | 24972782d0 | +------------------------------------------+------------+------------+ | boot_successes | 10 | 0 | | boot_failures | 0 | 12 | | BUG:unable_to_handle_kernel | 0 | 12 | | Oops:#[##] | 0 | 12 | | Kernel_panic-not_syncing:Fatal_exception | 0 | 12 | +------------------------------------------+------------+------------+ [ 29.182485] skip http request: cgi-bin/lkp-jobfile-append-var?job_file=/lkp/scheduled/vm-ivb41-yocto-i386-25/trinity-300s-yocto-tiny-i386-2016-04-22.cgz-24972782d0379cd7e2f1d049f642863223c4416b-20170207-63339-1useqcq-0.yaml&job_state=running -O /dev/null [ 40.737707] trinity-main uses obsolete (PF_INET,SOCK_PACKET) [ 40.800286] VFS: Warning: trinity-c0 using old stat() call. Recompile your binary. [ 41.048800] BUG: unable to handle kernel NULL pointer dereference at 0000001c [ 41.049642] IP: iput+0x9/0x142 [ 41.049990] *pde = 00000000 [ 41.049990] [ 41.050500] Oops: 0000 [#1] [ 41.050815] CPU: 0 PID: 330 Comm: trinity-c3 Not tainted 4.10.0-rc6-00059-g2497278 #1 [ 41.051675] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.9.3-20161025_171302-gandalf 04/01/2014 [ 41.052770] task: 4d900000 task.stack: 4d910000 [ 41.053278] EIP: iput+0x9/0x142 [ 41.053627] EFLAGS: 00010202 CPU: 0 [ 41.054013] EAX: 00000000 EBX: 534698dc ECX: 00000000 EDX: 00000000 [ 41.054699] ESI: 00000000 EDI: 5346bd48 EBP: 4d911f48 ESP: 4d911f34 [ 41.055385] DS: 007b ES: 007b FS: 0000 GS: 00e0 SS: 0068 [ 41.055976] CR0: 80050033 CR2: 0000001c CR3: 0d904000 CR4: 00000690 [ 41.056667] Call Trace: [ 41.056950] iterate_bdevs+0xfb/0x103 [ 41.057359] ? fdatawait_one_bdev+0x10/0x10 [ 41.057826] sys_sync+0x52/0x70 [ 41.058180] do_fast_syscall_32+0xa8/0x11c [ 41.058642] entry_SYSENTER_32+0x4e/0x7c [ 41.059072] EIP: 0x3774ebb1 [ 41.059393] EFLAGS: 00000216 CPU: 0 [ 41.059785] EAX: ffffffda EBX: 0000fb1a ECX: 70000008 EDX: 00000fb0 [ 41.060477] ESI: 000000b4 EDI: 00000019 EBP: 745e374c ESP: 3ffac65c [ 41.061165] DS: 007b ES: 007b FS: 0000 GS: 0033 SS: 007b [ 41.061762] Code: c8 00 00 00 eb ca b8 88 d3 a4 41 e8 cf 94 61 00 5a 89 d8 5b 5e 5f 5d c3 55 b8 01 00 00 00 89 e5 5d c3 55 89 e5 57 56 53 83 ec 08 <8b> 48 1c 85 c0 8b 71 20 89 4d f0 89 75 ec 0f 84 1e 01 00 00 f6 [ 41.063804] EIP: iput+0x9/0x142 SS:ESP: 0068:4d911f34 [ 41.064365] CR2: 000000000000001c [ 41.064751] ---[ end trace 30f07bfbc097c0f2 ]--- [ 41.080669] Kernel panic - not syncing: Fatal exception [ 41.081260] Kernel Offset: disabled Elapsed time: 50 To reproduce: git clone git://git.kernel.org/pub/scm/linux/kernel/git/wfg/lkp-tests.git cd lkp-tests bin/lkp qemu -k <bzImage> job-script # job-script is attached in this email Thanks, Xiaolong