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    SubjectRe: 2.6.31-rc2: BUG: unable to handle kernel NULL pointer dereference
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    Am Sonntag, den 12.07.2009, 22:26 +0200 schrieb Jiri Slaby:
    > On 07/12/2009 07:30 PM, Parag Warudkar wrote:
    > > static void selinux_write_opts(struct seq_file *m,
    > > 1012 struct security_mnt_opts *opts)
    > > 1013 {
    > > 1014 int i;
    > > 1015 char *prefix;
    > > 1016
    > > 1017 for (i = 0; i < opts->num_mnt_opts; i++) {
    > > 1018 char *has_comma;
    > > 1019
    > > 1020 if (opts->mnt_opts[i])
    > > 1021 has_comma = strchr(opts->mnt_opts[i], ',');
    > > ^^^^^^^^^^^^^^^^^^^^^^^^^
    > > And that is a NULL pointer dereference - but we just checked for
    > > opts->mnt_opts[i] for not NULL.
    >
    > Note, that there is not a NULL dereference. It dereferences 0x40 which
    > came in as %rdi. Looks like somebody assigned garbage in there.
    >
    > Or a single bit mem error. Is memtest OK with this machine?

    Will schedule a memtest run.

    >
    > What warning tainted the kernel before this oops is still interesting...

    There seems to be no OOPS before that BUG. Does a WARNING also set the G
    flag? Something like that:

    Jul 12 16:42:34 localhost kernel: [ 6179.647004] ------------[ cut here ]------------
    Jul 12 16:42:34 localhost kernel: [ 6179.647004] WARNING: at lib/kref.c:43 kref_get+0x2f/0x4c()
    Jul 12 16:42:34 localhost kernel: [ 6179.647004] Hardware name: MS-7250
    Jul 12 16:42:34 localhost kernel: [ 6179.647004] Modules linked in: rndis_wlan floppy olympic forcedeth [last unloaded: scsi_wait_scan]
    Jul 12 16:42:34 localhost kernel: [ 6179.647004] Pid: 27483, comm: pm-suspend Tainted: G W 2.6.31-rc2 #79
    Jul 12 16:42:34 localhost kernel: [ 6179.647004] Call Trace:
    Jul 12 16:42:34 localhost kernel: [ 6179.647004] [<ffffffff8106c1c6>] ? warn_slowpath_common+0x84/0xb2
    Jul 12 16:42:34 localhost kernel: [ 6179.647004] [<ffffffff8134876b>] ? kref_get+0x2f/0x4c
    Jul 12 16:42:34 localhost kernel: [ 6179.647004] [<ffffffff813476b2>] ? kobject_get+0x26/0x44
    Jul 12 16:42:34 localhost kernel: [ 6179.647004] [<ffffffff815a344f>] ? cpufreq_cpu_get+0x74/0xca
    Jul 12 16:42:34 localhost kernel: [ 6179.647004] [<ffffffff815a3675>] ? cpufreq_suspend+0x5f/0x16f
    Jul 12 16:42:34 localhost kernel: [ 6179.647004] [<ffffffff81044a4f>] ? disable_local_APIC+0x2d/0x6d
    Jul 12 16:42:34 localhost kernel: [ 6179.647004] [<ffffffff81449b54>] ? sysdev_suspend+0xa7/0x28d
    Jul 12 16:42:34 localhost kernel: [ 6179.647004] [<ffffffff810a1229>] ? suspend_devices_and_enter+0x11c/0x1e6
    Jul 12 16:42:34 localhost kernel: [ 6179.647004] [<ffffffff810a13d8>] ? enter_state+0xe5/0x14c
    Jul 12 16:42:34 localhost kernel: [ 6179.647004] [<ffffffff810a0841>] ? state_store+0xc1/0xf6
    Jul 12 16:42:34 localhost kernel: [ 6179.647004] [<ffffffff81178bb8>] ? sysfs_write_file+0xe6/0x137
    Jul 12 16:42:34 localhost kernel: [ 6179.647004] [<ffffffff81117d03>] ? vfs_write+0xb4/0x126
    Jul 12 16:42:34 localhost kernel: [ 6179.647004] [<ffffffff81117e5d>] ? sys_write+0x55/0x90
    Jul 12 16:42:34 localhost kernel: [ 6179.647004] [<ffffffff8102bf2b>] ? system_call_fastpath+0x16/0x1b
    Jul 12 16:42:34 localhost kernel: [ 6179.647004] ---[ end trace f7a4d612974b9b3e ]---

    Btw this seems also to be new in 2.6.31-rc2:
    Jul 12 16:42:34 localhost kernel: [ 6187.256748] sd 2:0:0:0: [sdb] Starting disk
    Jul 12 16:42:34 localhost kernel: [ 6190.318012]
    Jul 12 16:42:34 localhost kernel: [ 6190.318128] floppy driver state
    Jul 12 16:42:34 localhost kernel: [ 6190.318244] -------------------
    Jul 12 16:42:34 localhost kernel: [ 6190.320684] now=4300857616 last interrupt=4294760495 diff=6097121 last called handler=ffffffffa00263ea
    Jul 12 16:42:34 localhost kernel: [ 6190.320896] timeout_message=lock fdc
    Jul 12 16:42:34 localhost kernel: [ 6190.321018] last output bytes:
    Jul 12 16:42:34 localhost kernel: [ 6190.321135] f 80 4294754488
    Jul 12 16:42:34 localhost kernel: [ 6190.321251] 0 90 4294754489
    Jul 12 16:42:34 localhost kernel: [ 6190.321367] 1 91 4294754489
    Jul 12 16:42:34 localhost kernel: [ 6190.321484] 8 81 4294754493
    Jul 12 16:42:34 localhost kernel: [ 6190.321600] 4 80 4294756489
    Jul 12 16:42:34 localhost kernel: [ 6190.321717] 0 90 4294756489
    Jul 12 16:42:34 localhost kernel: [ 6190.321833] f 80 4294756489
    Jul 12 16:42:34 localhost kernel: [ 6190.321949] 0 90 4294756489
    Jul 12 16:42:34 localhost kernel: [ 6190.322073] 0 91 4294756490
    Jul 12 16:42:34 localhost kernel: [ 6190.322189] 8 81 4294756494
    Jul 12 16:42:34 localhost kernel: [ 6190.322305] f 80 4294758491
    Jul 12 16:42:34 localhost kernel: [ 6190.322421] 0 90 4294758491
    Jul 12 16:42:34 localhost kernel: [ 6190.322538] 1 91 4294758491
    Jul 12 16:42:34 localhost kernel: [ 6190.322654] 8 81 4294758496
    Jul 12 16:42:34 localhost kernel: [ 6190.322770] 4 80 4294760491
    Jul 12 16:42:34 localhost kernel: [ 6190.322886] 0 90 4294760491
    Jul 12 16:42:34 localhost kernel: [ 6190.323010] f 80 4294760491
    Jul 12 16:42:34 localhost kernel: [ 6190.323126] 0 90 4294760491
    Jul 12 16:42:34 localhost kernel: [ 6190.323243] 0 91 4294760491
    Jul 12 16:42:34 localhost kernel: [ 6190.323359] 8 81 4294760495
    Jul 12 16:42:34 localhost kernel: [ 6190.323475] last result at 4294760495
    Jul 12 16:42:34 localhost kernel: [ 6190.323591] last redo_fd_request at 4296147775
    Jul 12 16:42:34 localhost kernel: [ 6190.323708] 20 0
    Jul 12 16:42:34 localhost kernel: [ 6190.323869] status=4e
    Jul 12 16:42:34 localhost kernel: [ 6190.323984] fdc_busy=1
    Jul 12 16:42:34 localhost kernel: [ 6190.324107] do_floppy=ffffffffa0022263
    Jul 12 16:42:34 localhost kernel: [ 6190.324224] cont=ffffffffa002d190
    Jul 12 16:42:34 localhost kernel: [ 6190.324340] current_req=(null)
    Jul 12 16:42:34 localhost kernel: [ 6190.324456] command_status=-1
    Jul 12 16:42:34 localhost kernel: [ 6190.324572]
    Jul 12 16:42:34 localhost kernel: [ 6190.324689] floppy0: floppy timeout called
    Jul 12 16:42:34 localhost kernel: [ 6190.365498] PM: resume devices took 10.626 seconds

    greets
    thomas




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