On Mon, May 16, 2011 at 02:34:46PM +0530, Bharat Bhushan wrote: > I am using linux kernel version 2.6.16.51 MIPS port. > > I see the crash while using netlink_broadcast from kernel module. > > CPU 0 Unable to handle kernel paging request at virtual address > 00000000, epc == 8011c1c8, ra == 80120950 > Oops[#1]: > Cpu 0 > $ 0 : 00000000 50104c00 00000000 804008c0 > $ 4 : 803841a0 00000000 00000001 00000000 > $ 8 : 40000000 00000000 00000000 00000000 > $12 : 00000000 00000001 8093bfff 00000002 > $16 : 81201480 8120193c 8a69e018 881e1b80 > $20 : 8ba5a520 00000001 80412d34 00000000 > $24 : 00000000 80343f04 > $28 : 80382000 80383d08 80383d10 80120950 > Hi : 00000090 > Lo : 0000007e > epc : 8011c1c8 dequeue_task+0xc/0x94 Tainted: PF > ra : 80120950 sys_sched_yield+0x7c/0xf8 > Status: 50104c02 KERNEL EXL > Cause : 00808008 > BadVA : 00000000 > PrId : 000c0904 > Modules linked in: cf ipi_hsl dataplane evb sjtag xlr_fmn hw_random > ipt_connlimit xt_tcpudp xt_mark ipt_REDIRECT iptable_nat ip_nat > ip_conntrack iptable_filter ip_tables x_tables hwreset panic_dump > Process swapper (pid: 0, threadinfo=80382000, task=803841a0) > Stack : 80383d10 802c0180 ffffffff 00000001 8a69e018 881e1b80 ffffffff 00000001 > 00000001 802d6390 8e143390 00000000 8e11f848 8e002d8c 00000000 00000001 > 00000001 00000000 881e1c08 80410000 8e9c7f30 881e1b80 8fc7de00 8fc7def8 > 00000002 8e409400 8e143390 00000000 00000000 8e0d7840 817a3e00 0001164d > 00000000 00000000 000000d0 8e40c0e4 8e0d9ea0 8e0d9cb4 8e706738 00000002 > > > > Please note netlink_broadcast reserves Stack frame of 80bytes but > tries to write to access 88(sp). > > 802d60c8 <netlink_broadcast>: > 802d60c8: 27bdffb0 addiu sp,sp,-80 > 802d60cc: afb40038 sw s4,56(sp) > 802d60d0: afb30034 sw s3,52(sp) > 802d60d4: afbf004c sw ra,76(sp) > 802d60d8: afbe0048 sw s8,72(sp) > 802d60dc: afb70044 sw s7,68(sp) > 802d60e0: afb60040 sw s6,64(sp) > 802d60e4: afb5003c sw s5,60(sp) > 802d60e8: afb20030 sw s2,48(sp) > 802d60ec: afb1002c sw s1,44(sp) > 802d60f0: afb00028 sw s0,40(sp) > 802d60f4: afa40050 sw a0,80(sp) <-------Can this corrupt the > previous stack frame? > 802d60f8: 8ca20078 lw v0,120(a1) > 802d60fc: 00a09821 move s3,a1 > 802d6100: afa60058 sw a2,88(sp) <------- Can this corrupt the > previous stack frame? No; this is entirely normal. In the O32 ABI which is used to compile 32-bit kernels the caller allocates the stackframe for the callee to save the argument registers $a0 .. $a3 so you expect to see accesses to the 16 bytes above the current stack frame just like here. Ralf PS: 2.6.16.51 is now over 4 years old. Please ship to the following address: British Museum Great Russell Street WC1B 3DG London Great Britain ;-)
