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[Bug kprobes/5759] probes in sched.c on preempt kernel cause reboot
- From: "jkenisto at us dot ibm dot com" <sourceware-bugzilla at sourceware dot org>
- To: systemtap at sources dot redhat dot com
- Date: 12 Feb 2008 21:48:37 -0000
- Subject: [Bug kprobes/5759] probes in sched.c on preempt kernel cause reboot
- References: <20080212161826.5759.hunt@redhat.com>
- Reply-to: sourceware-bugzilla at sourceware dot org
------- Additional Comments From jkenisto at us dot ibm dot com 2008-02-12 21:48 -------
Created an attachment (id=2252)
--> (http://sourceware.org/bugzilla/attachment.cgi?id=2252&action=view)
oops from trying to install a kprobe on init_sched_debug_procfs
Following is a summary of the oops. For some reason, the kernel can't handle
the READ from the probepoint when we're trying to copy the probed instruction
into the kprobe_insn_page. This is from a 4-CPU x86_64 system running vanilla
2.6.24.
Unable to handle kernel paging request at ffffffff8086c9d0
rip is in arch_copy_kprobe(), 2nd line, first insn of inline memcpy:
movsl %ds:(%rsi),%es:(%rdi)
rip = ffffffff80472891
rsi = ffffffff8086c9d0
rdi = ffffffff8800000f
ds = 0
es = 0
rsi contains the address of init_sched_debug_procfs (i.e., the probepoint).
rdi contains MODULES_VADDR+0xf. This could be correct if the first
kprobe_insn_page was allocated right at MODULES_VADDR. MAX_INSN_SIZE=0xf for
x86_64, so this would be the start of the 2nd slot.
BTW, on 2.6.24, register_kprobe() works on many functions in kernel/sched.c,
but I've also see it fail on other probepoints besides this one.
--
http://sourceware.org/bugzilla/show_bug.cgi?id=5759
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