kernel of next-20170602 call trace when run add_key02 in LTP

[Bixuan Cui]

Hi,
Compile kernel (next-20170602) and run ltp, find:

/ # ./add_key02
tst_test.c:878: INFO: Timeout per run is 0h 05m 00s
[  341.183219] BUG: unable to handle kernel NULL pointer dereference at   (null)
[  341.183850] IP: memset+0x10/0x20
[  341.184550] *pdpt = 0000000035441001 *pde = 0000000000000000
[  341.184550]
[  341.184550] Oops: 0002 [#2] SMP
[  341.184550] Modules linked in:
[  341.184550] CPU: 0 PID: 124 Comm: add_key02 Tainted: G S    D W
  4.12.0-rc3-next-20170602 #3
[  341.184550] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996),
BIOS Bochs 01/01/2011
[  341.184550] task: f5b9ca00 task.stack: f6514000
[  341.184550] EIP: memset+0x10/0x20
[  341.184550] EFLAGS: 00000246 CPU: 0
[  341.184550] EAX: 00000000 EBX: 00000000 ECX: 00000001 EDX: 00000000
[  341.184550] ESI: 00000000 EDI: 00000000 EBP: f6515f24 ESP: f6515f1c
[  341.184550]  DS: 007b ES: 007b FS: 00d8 GS: 00e0 SS: 0068
[  341.184550] CR0: 80050033 CR2: 00000000 CR3: 36404920 CR4: 000006f0
[  341.184550] DR0: 00000000 DR1: 00000000 DR2: 00000000 DR3: 00000000
[  341.184550] DR6: 00000000 DR7: 00000000
[  341.184550] Call Trace:
[  341.184550]  memzero_explicit+0xf/0x20
[  341.184550]  SyS_add_key+0x11f/0x1c0
[  341.184550]  ? change_pid+0x13/0x50
[  341.184550]  do_fast_syscall_32+0x8b/0x130
[  341.184550]  entry_SYSENTER_32+0x4e/0x7c
[  341.184550] EIP: 0xb772ddc1
[  341.184550] EFLAGS: 00000246 CPU: 0
[  341.184550] EAX: ffffffda EBX: 080de341 ECX: 080de346 EDX: 00000000
[  341.184550] ESI: 00000001 EDI: fffffffc EBP: 0808aa97 ESP: bfe3636c
[  341.184550]  DS: 007b ES: 007b FS: 0000 GS: 0033 SS: 007b
[  341.184550] Code: 8a 0e 88 0f 8d b4 26 00 00 00 00 8b 45 f0 83 c4
04 5b 5e 5f 5d c3 90 8d 74 26 00 3e 8d 74 26 00 55 89 e5 57 89 c7 53
89 c3 89 d0 <f3> aa 89 d8 5b 5f 5d c3 90 90 90 90 90 90 90 90 3e 8d 74
26 00
[  341.184550] EIP: memset+0x10/0x20 SS:ESP: 0068:f6515f1c
[  341.184550] CR2: 0000000000000000
[  341.219144] ---[ end trace e3963c970d107f91 ]---
tst_test.c:928: INFO: If you are running on slow machine, try
exporting LTP_TIMEOUT_MUL > 1
tst_test.c:929: BROK: Test killed! (timeout?)

I try to use other tags and kernel on next-20170427 is ok, but
next-20170502 fail.
Is it bug?
Thanks,
Cui Bixuan