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    SubjectRe: [PATCH] mm: fix possible cause of a page_mapped BUG
    From
    >>> So, if this case is not caught later on in the code, I guess it solves
    >>> the problem. During the fuzzing I didn't experience any panic's, but
    >>> some other problems arose, i.e. cannot read /proc/<pid>/maps for some
    >>> processes (sys_read hangs, and such process cannot be killed or
    >>> stopped with any signal, still it's running (R state) and using CPU -
    >>> I'll submit another report for that).
    >>
    >> Hmm. Sounds like an endless loop in kernel mode.
    >>
    >> Use "perf record -ag" as root, it should show up very clearly in the report.
    >>
    >>                          Linus
    >
    > I've put some data here -
    > http://groups.google.com/group/fa.linux.kernel/browse_thread/thread/4345dcc4f7750ce2
    > - I think it's somewhat connected (sys_mlock appears on both cases).
    >
    > Attaching perf data (for 2.6.38) + kdb dumpall + procdump for process 14158
    >
    > Those 3 processes cannot be stopped/killed
    >
    > 14158 66.2  0.0   8380  3012 ?  RL  /tmp/iknowthis
    > 17100 63.6  0.1  18248  4004 ?  RL  /tmp/iknowthis
    > 19772 63.8  0.0   4000  1888 ?   RL  /tmp/iknowthis

    Also, the system doesn't look usable after such fuzzing (executing a
    few times some pretty deterministic program)

    root@ise-test:~# gcc -m32 mlock.c -o mlock

    root@ise-test:~# ./mlock
    ./mlock: relocation error: ./mlock: symbol perror, version GLIBC_2.0
    not defined in file libc.so.6 with link time reference

    root@ise-test:~# ./mlock
    mmap: Success
    RET: 0xf751f000
    mremap: Invalid argument
    RET: 0xffffffff

    root@ise-test:~# ./mlock
    Segmentation fault

    root@ise-test:~# dmesg | tail -n 1
    [ 5164.961568] mlock[7097]: segfault at 0 ip (null) sp
    00000000ff8a00d4 error 14 in mlock[8048000+1000]

    --
    Robert Święcki
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