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#65 NULL pointer at find_comp_page()

closed-fixed
None
5
2002-05-02
2002-04-30
No

kernel: Unable to handle kernel NULL pointer
dereference at virtual address
00000018
kernel: printing eip:
kernel: c0141d60
kernel: *pde = 04f9b067
kernel: *pte = 00000000
kernel: Oops: 0000
kernel: CPU: 0
kernel: EIP: 0010:[find_comp_page+24/104] Tainted: P
kernel: EFLAGS: 00210296
kernel: eax: 00000018 ebx: 00000000 ecx: c4d33ec0
edx: 0018bb00
kernel: esi: c4d33ec0 edi: 0018bb00 ebp: fffffffe
esp: c4d33ea0
kernel: ds: 0018 es: 0018 ss: 0018
kernel: Process colorize.pl (pid: 27913,
stackpage=c4d33000)
kernel: Stack: 02b20067 c10ac800 fffffffe c4f9a8b8
c014071b 02b20067 c10ac800
0018bb00
kernel: 00000000 c012fe42 0822e174 c5d20220
00000001 c72320e0 00000002
c14875a0
kernel: c013012c c5d20220 c72320e0 0822e174
c4f9a8b8 0018bb00 00000001
c4d32000
kernel: Call Trace: [flush_comp_cache+43/164]
[do_swap_page+338/384]
[handle_mm_fault+112/240] [do_page_faul
t+388/1204] [do_page_fault+0/1204]
kernel: [timer_bh+46/680] [bh_action+38/116]
[tasklet_hi_action+93/128]
[do_softirq+97/200] [do_IRQ+214/2
32] [error_code+52/64]

Discussion

  • Logged In: YES
    user_id=94481

    We were calling flush_comp_cache() for a page with no
    mapping, what caused the oops. That can happen since it
    might get removed from swap cache and only later be flushed
    from comp cache.Thus, now if there's no mapping, we assume
    it's swapper_space (since it's the only case), what fixes
    our problem.

     
    • status: open --> closed-fixed