Messages in this thread | | | From | Kyle Huey <> | Date | Sat, 16 Jul 2022 16:21:50 -0700 | Subject | Re: [PATCH 0/3] ptrace: Stop supporting SIGKILL for PTRACE_EVENT_EXIT |
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On Sat, Jul 16, 2022 at 2:31 PM Eric W. Biederman <ebiederm@xmission.com> wrote: > > "Eric W. Biederman" <ebiederm@xmission.com> writes: > > > Keno Fischer <keno@juliacomputing.com> writes: > > > >> Hi Eric, > >> > >> On Fri, Jul 8, 2022 at 6:25 PM Eric W. Biederman <ebiederm@xmission.com> wrote: > >>> > Recently I had a conversation where it was pointed out to me that > >>> > SIGKILL sent to a tracee stropped in PTRACE_EVENT_EXIT is quite > >>> > difficult for a tracer to handle. > >>> > > >>> > >>> RR folks any comments? > >>> > >>> Did I properly understand what Keno Fischer was asking for when we > >>> talked in person? > >> > >> Yes, this is indeed what I had in mind. I have not yet had the opportunity > >> to try out your patch series (sorry), but from visual inspection, it does indeed > >> do what I wanted, which is to make sure that a tracee stays in > >> PTRACE_EVENT_EXIT for the tracer to inspect, even if there is another > >> SIGKILL incoming simultaneously (since otherwise it may be impossible > >> for the tracer to observe the PTRACE_EVENT_EXIT if two SIGKILLs > >> come in rapid succession). I will try to take this series for a proper spin > >> shortly. > > > > Thanks, > > > > I haven't yet figured out how to get the rr test suite to run > > successfully. Something about my test machine and lack of perf counters > > seems to be causing problems. So if you can perform the testing on your > > side that would be fantastic. > > Ok. I finally found a machine where I can run rr and the rr test suite. > > It looks like there are a couple of the rr 5.5.0 test that fail on > Linus's lastest kernel simply because of changes in kernel behavior. In > particular clone_cleartid_coredump, and fcntl_rw_hints. The > clone_cleartid_coredump appears to fail because SIGSEGV no longer kills > all processes that share an mm. Which was a deliberate change.
Yeah, we changed to handle this in https://github.com/rr-debugger/rr/commit/04bbacdbaba1cc496e92060014442bd1fd26b41d and https://github.com/rr-debugger/rr/commit/1a3b389c2956e1844c0d07bf4297398bb6c561ea.
> With the lastest development version of rr, only detach_sigkill appears > to be failing on Linus's latest. That failure appears to be independent > of the patches in question as well. When run manually the > detach_sigkill test succeeds so I am not quite certain what is going on, > any thoughts?
If it fails before your changes I wouldn't worry about it too much, there's been some other failures in that test lately.
- Kyle
> As for my patchset it looks like it does not cause any new test failures > for rr so I will plan on getting it into linux-next shortly. > > Eric >
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