Re[3]: pty_chars_in_buffer NULL pointer (kernel oops)

From: nuclearcat (nuclearcat_at_nuclearcat.com)
Date: 02/27/05

  • Next message: KaiGai Kohei: "Re: [Lse-tech] Re: A common layer for Accounting packages"
    Date:	Sun, 27 Feb 2005 17:03:48 +0200
    To: nuclearcat <nuclearcat@nuclearcat.com>
    
    

    Dear, nuclearcat.

    You wrote Sunday, February 27, 2005, 4:52:54 PM:

    P.S. new kernel - 2.4.29 vanilla

    > Dear, Marcelo.

    > You wrote Saturday, February 26, 2005, 1:04:32 AM:

    > Sorry about delay, i had switched kernel to non-SMP mode.
    > I cannot debug on kernel (it is loaded VPN server, and there is no
    > redundancy for now).
    > I have only few old oopses, saved before (it is on old redhat kernel)
    > Feb 16 06:44:41 nss kernel: Unable to handle kernel NULL pointer
    > dereference at virtual address 00000000
    > Feb 16 06:44:41 nss kernel: printing eip:
    > Feb 16 06:44:41 nss kernel: 00000000
    > Feb 16 06:44:41 nss kernel: *pde = 00000000
    > Feb 16 06:44:41 nss kernel: Oops: 0000
    > Feb 16 06:44:41 nss kernel: cls_u32 sch_sfq sch_cbq ip_nat_ftp
    > ip_conntrack_ftp tun ipt_REJECT ipt_REDIRECT nls_iso8859-1 loop
    > cipcb ip_gre ipip ppp_async pp
    > Feb 16 06:44:41 nss kernel: CPU: 3
    > Feb 16 06:44:41 nss kernel: EIP: 0060:[<00000000>] Not tainted
    > Feb 16 06:44:41 nss kernel: EFLAGS: 00010286
    > Feb 16 06:44:41 nss kernel:
    > Feb 16 06:44:41 nss kernel: EIP is at [unresolved] (2.4.20-20.9smp)
    > Feb 16 06:44:41 nss kernel: eax: d4b26000 ebx: ce7fe000 ecx: c01997c0 edx: ef7c6b80
    > Feb 16 06:44:41 nss kernel: esi: 00000000 edi: ce7fe000 ebp: e040a880 esp: cfdf7ee0
    > Feb 16 06:44:41 nss kernel: ds: 0068 es: 0068 ss: 0068
    > Feb 16 06:44:41 nss kernel: Process pptpctrl (pid: 15960, stackpage=cfdf7000)
    > Feb 16 06:44:41 nss kernel: Stack: c019d839 d4b26000 00000000
    > c019b2e6 ce7fe000 ce7fe974 cfdf7f48 ce7fe000
    > Feb 16 06:44:41 nss kernel: e040a880 00000004 00000010
    > c0197a15 ce7fe000 e040a880 00000000 00000000
    > Feb 16 06:44:41 nss kernel: e040a880 c01662b7 e040a880
    > 00000000 cfdf6000 00000145 cfdf6000 00001962
    > Feb 16 06:44:41 nss kernel: Call Trace: [<c019d839>]
    > pty_chars_in_buffer [kernel] 0x39 (0xcfdf7ee0))
    > Feb 16 06:44:41 nss kernel: [<c019b2e6>] normal_poll [kernel] 0x106 (0xcfdf7eec))
    > Feb 16 06:44:41 nss kernel: [<c0197a15>] tty_poll [kernel] 0x85 (0xcfdf7f0c))
    > Feb 16 06:44:41 nss kernel: [<c01662b7>] do_select [kernel] 0x247 (0xcfdf7f24))
    > Feb 16 06:44:41 nss kernel: [<c016663e>] sys_select [kernel] 0x34e (0xcfdf7f60))
    > Feb 16 06:44:41 nss kernel: [<c01098cf>] system_call [kernel] 0x33 (0xcfdf7fc0))
    > Feb 16 06:44:41 nss kernel:
    > Feb 16 06:44:41 nss kernel:
    > Feb 16 06:44:41 nss kernel: Code: Bad EIP value.

    > in new kernel there is no debug messages to find where is problem, but
    > problem looks very similar

    > Feb 17 13:13:54 nss kernel: Unable to handle kernel NULL pointer
    > dereference at virtual address 00000000
    > Feb 17 13:13:54 nss kernel: printing eip:
    > Feb 17 13:13:54 nss kernel: 00000000
    > Feb 17 13:13:54 nss kernel: *pde = 00000000
    > Feb 17 13:13:54 nss kernel: Oops: 0000
    > Feb 17 13:13:54 nss kernel: CPU: 3
    > Feb 17 13:13:54 nss kernel: EIP: 0010:[<00000000>] Not tainted
    > Feb 17 13:13:54 nss kernel: EFLAGS: 00010286
    > Feb 17 13:13:54 nss kernel: eax: ec32e000 ebx: f6891000 ecx: c01f56a0 edx: d6547980
    > Feb 17 13:13:54 nss kernel: esi: f6891000 edi: 00000000 ebp: f39c4c00 esp: d66bbed8
    > Feb 17 13:13:54 nss kernel: ds: 0018 es: 0018 ss: 0018
    > Feb 17 13:13:54 nss kernel: Process pptpctrl (pid: 10632, stackpage=d66bb000)
    > Feb 17 13:13:54 nss kernel: Stack: c01f9829 ec32e000 00000000
    > c01f7e66 f6891000 00000010 00000202 f68910c0
    > Feb 17 13:13:54 nss kernel: f6891000 f39c4c00 00000000
    > c01f3bb0 f6891000 f39c4c00 00000000 00000000
    > Feb 17 13:13:54 nss kernel: f39c4c00 00000004 00000010
    > c0153a87 f39c4c00 00000000 d66ba000 00000145
    > Feb 17 13:13:54 nss kernel: Call Trace: [<c01f9829>]
    > [<c01f7e66>] [<c01f3bb0>] [<c0153a87>] [<c0153e0e>]
    > Feb 17 13:13:54 nss kernel: [<c010ae99>] [<c0108f67>]
    > Feb 17 13:13:54 nss kernel:
    > Feb 17 13:13:54 nss kernel: Code: Bad EIP value.

    > And problem disappearing in non-SMP kernel.

    >> Hi,

    >> On Fri, Feb 18, 2005 at 10:56:53AM +0200, nuclearcat wrote:

    >>> Is discussed at

    >>> http://kerneltrap.org/mailarchive/1/message/12508/thread

    >>> bug fixed in 2.4.x tree? Cause seems i have downloaded 2.4.29, and it
    >>> is not fixed (still my kernel on vpn server crashing almost at start),
    >>> i have grepped fast pre and bk patches, but didnt found any fixed
    >>> related to tty/pty.

    >> Can you please post the oops? Have you done so already?

    >> What makes you think it is the same race discussed in the above thread?

    >> BTW, I fail to see any drivers/char/pty.c change related to the race which triggers
    >> the pty_chars_in_buffer->0 oops.

    >> Quoting the first message from thread you mention:
    >> "That last call trace entry is the call in pty_chars_in_buffer() to

    >> /* The ldisc must report 0 if no characters available to be read */
    >> count = to->ldisc.chars_in_buffer(to);
    >> "

    >> Alan, Linus, what correction to the which the above thread discusses has
    >> been deployed?

    >>> Provided in thread patch from Linus working, but after night i have
    >>> checked server, and see load average jumped to 700.
    >>> Can anybody help in that? I am not kernel guru to provide a patch, but
    >>> seems by search in google it is actual problem for people, who own
    >>> poptop vpn servers, it is really causing serious instability for
    >>> servers.

    >> Can you compile a list of such v2.4 reports?
    >> -
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    -- 
    With best regards,
    GlobalProof Globax Division Manager,
    Denys Fedoryshchenko
    mailto:denys@globalproof.net
    -
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