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[Bug runtime/12164] stap script causing ptrace to error with "Device or resource busy"
- From: "jistone at redhat dot com" <sourceware-bugzilla at sourceware dot org>
- To: systemtap at sources dot redhat dot com
- Date: Thu, 28 Oct 2010 21:05:44 +0000
- Subject: [Bug runtime/12164] stap script causing ptrace to error with "Device or resource busy"
- Auto-submitted: auto-generated
- References: <bug-12164-1110@http.sourceware.org/bugzilla/>
http://sourceware.org/bugzilla/show_bug.cgi?id=12164
Josh Stone <jistone at redhat dot com> changed:
What |Removed |Added
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CC| |jistone at redhat dot com
--- Comment #5 from Josh Stone <jistone at redhat dot com> 2010-10-28 21:05:39 UTC ---
(In reply to comment #3)
> I bisected the bug down to b642c901a918a92fdd6b1167ed02dfe4c50cdd3e:
>
> Add kprobe user probe semaphore handling.
So, the reason this commit came up is that it started enabling task_finder when
kprobes are used. We should probably try to narrow this to just for
SDT-related kprobes, but that's not really the issue here.
(In reply to comment #4)
> jistone on #systemtap had me run this systemtap script: [... process.begin ...]
This was to explicitly use utrace, thus even older stap is affected.
> this was reproducible down to systemtap 0.9.9 on Fedora 11 kernel
> 2.6.31.12-172.2.22.fc11, but not reproducible on Fedora 13 kernel 13
> 2.6.33.5-112.fc13.
I found out from Erick that his F11 kernel is actually a backport from
2.6.31.12-174.2.22.fc12. I don't have an F11 VM anymore, but I downloaded this
kernel from koji onto my F12 VM, and sure enough, strace gets EBUSY whenever a
stap-utrace probe is active. Both i686 and x86_64 have this problem on that
kernel, but work fine on with the latest F12 kernel, 2.6.32.21-168.fc12.
It's not just strace either. While stap is using utrace, gdb also gets EBUSY
trying to attach to a process, and sees no activity at all when trying to start
its own inferior. It seems that utrace on that kernel is not meeting its
multiple-client promise...
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