Date: Fri, 7 Oct 2016 15:18:48 +0300 From: Konstantin Belousov <kostikbel@gmail.com> To: Andy Farkas <chuzzwassa@gmail.com> Cc: freebsd-stable@freebsd.org Subject: Re: Reproducible panic - Going nowhere without my init! Message-ID: <20161007121848.GY38409@kib.kiev.ua> In-Reply-To: <CAAJ1ec1omKtGBXATvyC96N22Ue6s6wp_dfmdkHGWDoqBfehMcw@mail.gmail.com> References: <CAAJ1ec1omKtGBXATvyC96N22Ue6s6wp_dfmdkHGWDoqBfehMcw@mail.gmail.com>
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On Fri, Oct 07, 2016 at 08:32:24AM +1000, Andy Farkas wrote: > With your latest patch applied, I ran through my procedure more > than a dozen times and no panics! > > Any explanation why sleep(STALL_TIMEOUT) as apposed to a > bunch of sleep(1)'s tickles the panic? What happened was sleep() got interrupted by a signal. Normally reboot(8) stops init with SIGTSTP, then kill processes, then calls reboot(2). reboot(8) does not and cannot get acknowledges for the receipts of the signals by signalled processes, which indeed may result in the sleep interruption if other signal is delivered to init before SIGTSTP. Patch does not add 'just bunch of sleeps'. The code in the patch ensures that _exit() is called not earlier than STALL_TIMEOUT from the moment of detection of the shell exit, by reissuing sleep(). I changed the argument to 1 second to avoid situation where we e.g. sleep for 15 secs, get interrupt and then sleep for whole 30 secs. The overtime with sleep(1) is limited to 1 second. > > Also, it is definitely not sleeping for 30 seconds. I guess some > event interrupts the sleep loop?
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