CODEWITHSUNDEEP
linuxkernel
Tulip
Tulip

Reputation: 193

Kernel oops -Page protection fault

My kernel oopsed at kmem_cache_alloc with Oops number 5. I googled what that denotes, and found that it means 'Page protection fault during read access in user mode'. I am not able to find what page protection fault is. Is it the same as general protection fault?

[  402.554964] Unable to handle kernel NULL pointer dereference at virtual address 00000001
[  402.562995] pgd = c84ac000
[  402.566132] [00000001] *pgd=00000000
[  402.573958] Internal error: Oops: 5 [#1] PREEMPT SMP ARM
[  402.579209] Modules linked in: bcmdhd
[  402.582923] CPU: 0 PID: 2507 Comm: MediaScannerSer Not tainted 3.10.10+ #1
[  402.589703] task: c7eab480 ti: c23b0000 task.ti: c23b0000
[  402.595036] PC is at kmem_cache_alloc+0x78/0x1c4
[  402.599603] LR is at fat_parse_long+0x2e4/0x314
[  402.604095] pc : [<c01031bc>]    lr : [<c01f3f2c>]    psr: 20000013
[  402.604095] sp : c23b1bf8  ip : c23b1c38  fp : c23b1c34
[  402.615400] r10: 007d9000  r9 : 00000000  r8 : c01f3f2c
[  402.620579] r7 : 000000d0  r6 : ef001b80  r5 : c23b0000  r4 : 00000001
[  402.637275] r3 : 00000000  r2 : c23b1c9c  r1 : 000000d0  r0 : ef001b80
[  402.643702] Flags: nzCv  IRQs on  FIQs on  Mode SVC_32  ISA ARM  Segment user
[  402.650719] Control: 10c5387d  Table: 584ac06a  DAC: 00000015

Thanks in advance.

Upvotes: 1

Views: 4257

Answers (1)

Federico
Federico

Reputation: 3892

[  402.554964] Unable to handle kernel NULL pointer dereference at virtual address 00000001

Probably, you have a NULL pointer somewhere in your code. You have something like this:

my_variable->my_sub_structure->my_field

where my_sub_structure is NULL, so the code tries to reach my_field from an invalid memory address.

Upvotes: 4

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