From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alexey Dobriyan Subject: Banning checkpoint (was: Re: What can OpenVZ do?) Date: Thu, 19 Feb 2009 22:06:37 +0300 Message-ID: <20090219190637.GA4846@x200.localdomain> References: <20090213105302.GC4608@elte.hu> <1234817490.30155.287.camel@nimitz> <20090217222319.GA10546@elte.hu> <1234909849.4816.9.camel@nimitz> <20090218003217.GB25856@elte.hu> <1234917639.4816.12.camel@nimitz> <20090218051123.GA9367@x200.localdomain> <20090218181644.GD19995@elte.hu> <1234992447.26788.12.camel@nimitz> <20090218231545.GA17524@elte.hu> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20090218231545.GA17524@elte.hu> Sender: owner-linux-mm@kvack.org To: Ingo Molnar Cc: Dave Hansen , Nathan Lynch , linux-api@vger.kernel.org, containers@lists.linux-foundation.org, mpm@selenic.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, viro@zeniv.linux.org.uk, hpa@zytor.com, Andrew Morton , torvalds@linux-foundation.org, tglx@linutronix.de, xemul@openvz.org List-Id: linux-api@vger.kernel.org I think that all these efforts to abort checkpoint "intelligently" by banning it early are completely misguided. "Checkpointable" property isn't one-way ticket like "tainted" flag, so doing it like tainted var isn't right, atomic or not, SMP-safe or not. With filesystems, one has ->f_op field to compare against banned filesystems, one more flag isn't necessary. Inotify isn't supported yet? You do if (!list_empty(&inode->inotify_watches)) return -E; without hooking into inotify syscalls. ptrace(2) isn't supported -- look at struct task_struct::ptraced and friends. And so on. System call (or whatever) does something with some piece of kernel internals. We look at this "something" when walking data structures and abort if it's scary enough. Please, show at least one counter-example. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org