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Unable to handle kernel NULL pointer dereference at virtual address 00000004

Hi, i run a program on DM6467, sometimes come across the messages as follows, after the program run a moment every time at start.

What's wrong will result this exception?

Unable to handle kernel NULL pointer dereference at virtual address 00000004
[05-27 11:50:19]pgd = c0004000
[05-27 11:50:19][00000004] *pgd=00000000
[05-27 11:50:19]Internal error: Oops: 817 [#1]
[05-27 11:50:19]Modules linked in: dsplinkk
[05-27 11:50:19]CPU: 0
[05-27 11:50:19]PC is at free_block+0x60/0x124
[05-27 11:50:19]LR is at cache_flusharray+0x80/0xbc
[05-27 11:50:19]pc : [<c0067c54>]    lr : [<c0067e40>]    Tainted: PF   
[05-27 11:50:19]sp : c04b3e48  ip : c04b3e70  fp : c04b3e6c
[05-27 11:50:19]r10: 00000080  r9 : 00000080  r8 : c0482af0
[05-27 11:50:19]r7 : 00000000  r6 : 00000008  r5 : c044fbe0  r4 : c1000000
[05-27 11:50:19]r3 : 00000000  r2 : c107f060  r1 : c0482af0  r0 : c1000b48
[05-27 11:50:19]Flags: Nzcv  IRQs off  FIQs on  Mode SVC_32  Segment kernel
[05-27 11:50:19]Control: 5317F  Table: 82724000  DAC: 00000017
[05-27 11:50:19]Process kswapd0 (pid: 106, stack limit = 0xc04b21a0)
[05-27 11:50:19]Stack: (0xc04b3e48 to 0xc04b4000)
[05-27 11:50:19]3e40:                   c03d8030 c040ce20 c0482ae0 c04b2000 00000008 00000000
[05-27 11:50:19]3e60: c04b3e8c c04b3e70 c0067e40 c0067c04 c0482ae0 c0482af0 c2feb368 a0000013
[05-27 11:50:19]3e80: c04b3eac c04b3e90 c0067b28 c0067dd0 c2feb3a8 c2feb3a8 c04b3ef0 00000049
[05-27 11:50:19]3ea0: c04b3ec4 c04b3eb0 c0097574 c0067af8 c2feb4b0 c2feb3b0 c04b3ee4 c04b3ec8
[05-27 11:50:19]3ec0: c0098840 c0097540 c04b2000 c1072910 c04b2000 c02a4404 c04b3f24 c04b3ee8
[05-27 11:50:19]3ee0: c0098ac0 c0098780 c04b3ee8 00000076 c2feb670 c07f11f0 c03a6c00 00000080
[05-27 11:50:19]3f00: 00000080 00000080 00000000 c03ff6c0 c02a39ec 00000040 c04b3f5c c04b3f28
[05-27 11:50:19]3f20: c006a964 c00988ac 00002175 000000d0 c04b3f5c c02a3340 00000001 00000000
[05-27 11:50:19]3f40: c02a3340 00000000 00000000 00000006 c04b3ff4 c04b3f60 c006c1c4 c006a8a0
[05-27 11:50:19]3f60: 00002175 c04b3f74 00000018 00000000 c04b2000 00000003 0000001a 00000040
[05-27 11:50:19]3f80: 00000009 00001189 00000017 00000006 000000d0 00000000 00000000 c04392e0
[05-27 11:50:19]3fa0: c0057d98 c04b3fbc c04b3fbc c003b74c 00000000 c04392e0 c0057d98 c04b3fbc
[05-27 11:50:19]3fc0: c04b3fbc 00000000 00000000 00000000 00000000 00000000 00000000 00000000
[05-27 11:50:19]3fe0: 00000000 00000000 00000000 c04b3ff8 c0041f54 c006bf48 000020a0 00000600
[05-27 11:50:19]Backtrace:
[05-27 11:50:19][<c0067bf4>] (free_block+0x0/0x124) from [<c0067e40>] (cache_flusharray+0x80/0xbc)
[05-27 11:50:19] r8 = 00000000  r7 = 00000008  r6 = C04B2000  r5 = C0482AE0
[05-27 11:50:19] r4 = C040CE20
[05-27 11:50:19][<c0067dc0>] (cache_flusharray+0x0/0xbc) from [<c0067b28>] (kmem_cache_free+0x40/0x58)
[05-27 11:50:19] r7 = A0000013  r6 = C2FEB368  r5 = C0482AF0  r4 = C0482AE0
[05-27 11:50:19][<c0067ae8>] (kmem_cache_free+0x0/0x58) from [<c0097574>] (destroy_inode+0x44/0x5c)
[05-27 11:50:19] r7 = 00000049  r6 = C04B3EF0  r5 = C2FEB3A8  r4 = C2FEB3A8
[05-27 11:50:19][<c0097530>] (destroy_inode+0x0/0x5c) from [<c0098840>] (dispose_list+0xd0/0x12c)
[05-27 11:50:19] r4 = C2FEB3B0
[05-27 11:50:19][<c0098770>] (dispose_list+0x0/0x12c) from [<c0098ac0>] (shrink_icache_memory+0x224/0x2d4)
[05-27 11:50:19] r7 = C02A4404  r6 = C04B2000  r5 = C1072910  r4 = C04B2000
[05-27 11:50:19][<c009889c>] (shrink_icache_memory+0x0/0x2d4) from [<c006a964>] (shrink_slab+0xd4/0x140)
[05-27 11:50:19][<c006a890>] (shrink_slab+0x0/0x140) from [<c006c1c4>] (kswapd+0x28c/0x394)
[05-27 11:50:19][<c006bf38>] (kswapd+0x0/0x394) from [<c0041f54>] (do_exit+0x0/0xda0)
[05-27 11:50:19]Code: e592401c e5942004 e5943000 e5823000 (e5832004)
[05-27 11:50:19] <6>note: kswapd0[106] exited with preempt_count 1
[05-27 11:50:19]BUG: scheduling while atomic: kswapd0/0x00000001/106
[05-27 11:50:19]caller is do_exit+0xd3c/0xda0
[05-27 11:50:20]Unable to handle kernel NULL pointer dereference at virtual address 00000004
[05-27 11:50:20]pgd = c0004000
[05-27 11:50:20][00000004] *pgd=00000000
[05-27 11:50:20]Internal error: Oops: 817 [#2]
[05-27 11:50:20]Modules linked in: dsplinkk
[05-27 11:50:20]CPU: 0
[05-27 11:50:20]PC is at free_block+0x60/0x124
[05-27 11:50:20]LR is at drain_array_locked+0x88/0xa8
[05-27 11:50:20]pc : [<c0067c54>]    lr : [<c0067da0>]    Tainted: PF   
[05-27 11:50:20]sp : c042ded0  ip : c042def8  fp : c042def4
[05-27 11:50:20]r10: c032460c  r9 : c032461c  r8 : c0482af0
[05-27 11:50:20]r7 : 00000000  r6 : 00000004  r5 : c044fbe0  r4 : c1000000
[05-27 11:50:20]r3 : 00000000  r2 : c107f060  r1 : c0482af0  r0 : c1000b48
[05-27 11:50:20]Flags: Nzcv  IRQs off  FIQs on  Mode SVC_32  Segment kernel
[05-27 11:50:20]Control: 5317F  Table: 82724000  DAC: 00000017
[05-27 11:50:20]Process events/0 (pid: 4, stack limit = 0xc042c1a0)
[05-27 11:50:20]Stack: (0xc042ded0 to 0xc042e000)
[05-27 11:50:20]dec0:                                     c256d000 00000004 c0482ae0 00000010
[05-27 11:50:20]dee0: c0482af0 c044fbe0 c042df1c c042def8 c0067da0 c0067c04 c0067bd4 00000000
[05-27 11:50:20]df00: c044fbe0 c042c000 c044fc50 00000001 c042df54 c042df20 c0068bb0 c0067d28
[05-27 11:50:20]df20: 00000000 c0409428 c042df54 c042c000 c0324628 00000000 c0409420 c032352c
[05-27 11:50:20]df40: 00000000 c0409428 c042dfc4 c042df58 c0051864 c0068b14 c0411f24 c0068b04
[05-27 11:50:20]df60: ffffffff ffffffff 00000001 00000000 c003b884 00010000 00000000 c042c000
[05-27 11:50:20]df80: 00000000 c0404540 c003b884 00100100 00200200 00000000 c042dfc4 c0409420
[05-27 11:50:20]dfa0: c042c000 c0411f20 c0051618 fffffffc 00000000 00000000 c042dff4 c042dfc8
[05-27 11:50:20]dfc0: c005781c c0051628 ffffffff ffffffff 00000000 00000000 00000000 00000000
[05-27 11:50:20]dfe0: 00000000 00000000 00000000 c042dff8 c0041f54 c0057744 c029e86c c029e86c
[05-27 11:50:20]Backtrace:
[05-27 11:50:20][<c0067bf4>] (free_block+0x0/0x124) from [<c0067da0>] (drain_array_locked+0x88/0xa8)
[05-27 11:50:20] r8 = C044FBE0  r7 = C0482AF0  r6 = 00000010  r5 = C0482AE0
[05-27 11:50:20] r4 = 00000004
[05-27 11:50:20][<c0067d18>] (drain_array_locked+0x0/0xa8) from [<c0068bb0>] (cache_reap+0xac/0x248)
[05-27 11:50:20] r8 = 00000001  r7 = C044FC50  r6 = C042C000  r5 = C044FBE0
[05-27 11:50:20] r4 = 00000000
[05-27 11:50:20][<c0068b04>] (cache_reap+0x0/0x248) from [<c0051864>] (worker_thread+0x24c/0x314)
[05-27 11:50:20][<c0051618>] (worker_thread+0x0/0x314) from [<c005781c>] (kthread+0xe8/0x11c)
[05-27 11:50:20][<c0057734>] (kthread+0x0/0x11c) from [<c0041f54>] (do_exit+0x0/0xda0)
[05-27 11:50:20] r8 = 00000000  r7 = 00000000  r6 = 00000000  r5 = 00000000
[05-27 11:50:20] r4 = 00000000
[05-27 11:50:20]Code: e592401c e5942004 e5943000 e5823000 (e5832004)
[05-27 11:50:20] <6>note: events/0[4] exited with preempt_count 1
[05-27 11:50:20]BUG: scheduling while atomic: events/0/0x00000001/4
[05-27 11:50:20]caller is do_exit+0xd3c/0xda0