On 06/20, Linus Torvalds wrote: > > On Wed, 20 Jun 2007, Oleg Nesterov wrote: > > > > Also, suppose that some thread does > > > > for (;;) > > signal(SIGSEGV, SIG_IGN); > > > > Now we have the same situation. do_sigaction() can steal SIGSEGV from > > another thread. > > Actually, that shouldn't be possible. > > See "force_sig_info()". It does not allow blocking or ignoring forced > signals. We will reset such a signal handler to SIG_DFL, and unlock it. > > So if you get a SIGSEGV while SIGSEGV's are blocked or ignored, the kernel > *will* kill you. No questions asked.
Yes, and no. Yes, force_sig() unblocks and un-ignores the signal. However, unlike group-wide signals, thread-specific signals do not convert themselves to SIGKILL on delivery. The target thread should dequeue SIGSEGV and then it calls do_group_exit(). Before it does so, another thread doing signal(SIGSEGV, SIG_IGN) can steal the signal. Of course, this is unlikely, and the target thread will take page fault again. The same for signalfd. Oleg. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
