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Biederman" Cc: Andrew Morton , Andy Lutomirski , Kees Cook , Kusaram Devineni , Peter Zijlstra , Thomas Gleixner , Will Drewry , linux-kernel@vger.kernel.org, Linus Torvalds , Christian Brauner Subject: Re: [PATCH v2 00/14] Short circuit delivery for coredump signals Message-ID: References: <87o6gx9rc4.fsf@email.froward.int.ebiederm.org> <877bnh7tnf.fsf@email.froward.int.ebiederm.org> <877bnb4uyw.fsf_-_@email.froward.int.ebiederm.org> <87mrw0wez9.fsf@email.froward.int.ebiederm.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87mrw0wez9.fsf@email.froward.int.ebiederm.org> X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.93 On 07/09, Eric W. Biederman wrote: > > Oleg Nesterov writes: > > > Hmm. And it seems that V2 doesn't fix the problem I noticed in V1: the dumper > > thread can be wrong. > > > > The first thread which calls get_signal() -> dequeue_exit_signal() will > > initiate the coredumping, not necessary the faulting thread. This looks > > very wrong to me. ... > With the signal on the shared_pending queue any thread can initiate the > core dump without problems. Yes, > The only other effect I can see is that the order of the threads notes > as written into the coredump with fill_note_info will be different. > Perhaps a debugger takes that as a signal to report which thread has > died? AFAIK gdb assumes that the the first NT_PRSTATUS in the core dump is the "crashed thread". If the wrong thread is the dumper, the developer will see the unrelated stack trace / etc. How can the user find the faulted thread which actually triggered the coredump? I think this is another regression which should be fixed. Oleg.