Date: Mon, 21 Nov 2016 16:25:42 +0100 From: Volker Lendecke <Volker.Lendecke@SerNet.DE> To: Konstantin Belousov <kostikbel@gmail.com> Cc: freebsd-hackers@freebsd.org Subject: Re: process shared mutexes? Message-ID: <20161121152542.GA31733@sernet.de> In-Reply-To: <20161121151040.GA54029@kib.kiev.ua> References: <20161121133528.GA30947@sernet.de> <20161121135036.GY54029@kib.kiev.ua> <20161121141616.GB30947@sernet.de> <20161121151040.GA54029@kib.kiev.ua>
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On Mon, Nov 21, 2016 at 05:10:40PM +0200, Konstantin Belousov wrote: > Please see the libthr(3) man page, in particular, read the RUN-TIME > SETTINGS section, the description of the kern.ipc.umtx_vnode_persistent > sysctl. > > Does setting the sysctl to 1 allow your program to run ? Yes, that does make it work. The description says that the umtx vnode is dropped on the last munmap. If I #if 0 the middle mmap, it works, although there is no mmap around anymore. So the description is not 100% accurate I'd say. When does the recycling happen exactly? Can it break running applications? And -- how can I make sure for Samba that this is set properly at runtime? We already have a runtime mutex test for some ancient Linux kernels that were broken. We could add this as a subtest too. But -- what happens if the admin resets this while Samba is running? Does the kernel make sure that existing files still get the correct behaviour when the sysctl changes? Thanks! Volkerhome | help
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