Become a fan of Slashdot on Facebook

 



Forgot your password?
typodupeerror
Check out the new SourceForge HTML5 internet speed test! No Flash necessary and runs on all devices. ×

Comment In a nutshell (Score 1) 109

This is an ancient bug that was actually attempted to be fixed once (badly) by me [Phil "not Paul" Oester] eleven years ago in commit 4ceb5db9757a ("Fix get_user_pages() race for write access") but that was then undone due to problems on s390 by commit f33ea7f404e5 ("fix get_user_pages bug").
In the meantime, the s390 situation has long been fixed, and we can now fix it by checking the pte_dirty() bit properly (and do it better).
The s390 dirty bit was implemented in abf09bed3cce ("s390/mm: implement software dirty bits") which made it into v3.9. Earlier kernels will have to look at the page state itself.
Also, the VM has become more scalable, and what used a purely theoretical race back then has become easier to trigger. To fix it, we introduce a new internal FOLL_COW flag to mark the "yes, we already did a COW" rather than play racy games with FOLL_WRITE that is very fundamental, and then use the pte dirty flag to validate that the FOLL_COW flag is still valid.

tl;dr? It only became a serious flaw recently. It's been fixed. Install the fix.
apt-get update&&apt-get -y upgrade&&reboot

I'm not surprised that a published vulnerability is being exploited. Nor am I surprised that problem has been fixed, (and the fix was available immediately instead of on Patch Tuesday), or that some people are running systems that haven't been updated with the fix.

Comment Re:1Million People (Score 1) 497

it's extremely rare on Earth ... $2 Billion is not the limit of demand, it's the limit of supply

Do you have evidence for a large pent-up demand for deuterium that would be released by a price drop of less than five times? (That would take it down to about the price of silver.)

No. Nor would I be stupid enough to assume the price would drop just because the supply increases (processing cost may not drop). Do you have any evidence to support your claim that the price is based soley on demand? Evidence for the absurd assertion that the cost would drop to the same a silver if the supply increased by a factor five?

Hint: nobody makes anything other than tiny amounts of deuterium anymore - not due to lack of demand. (the last supplier was Canada some years ago - though at least one Chinese source is gearing up for production).

the two would be of value for fueling fusion rockets

That's a technology that does not currently exist, and which might not actually use deuterium or tritium when/if it finally gets going.

Agreed

less than one tenth of what the USA spends annually on the bullshit War on Drugs

This is an irrelevant point of comparison. I'm asking for a business case; you can claim anything is "economically viable" if you're allowed to just steal something else' budget. That argument doesn't tend to convince the people who actually control such budgets, though.

Patently and demonstrably you did not ask for a business case - you just conflated the cost of the theoretical mission with government spending and are now distract. It's hardly irrelevant, it demonstrates what the US government is happy to spend on a demonstrably pointless exercise.

it's just a by-product of potable water production.

This is a ridiculous statement which suggests that you have no idea how deuterium is actually refined,

:) Which only goes to show you are yet another ultracrepidarian /. poster. Perhaps you are a mechanical engineer that thinks industrial chemical engineering is intuitive - good luck with the job interviews.

Extracting it on Mars will require dedicated machinery and tons of additional energy, just like on Earth.

No. Read the source I provided instead of relying of what you skim-read from someone else's outdated opinion.

Red Herring alert! Can you point to the source of your claim that this fleet won't be waiting for results from surface probes (and many robotic test trips)?!

Musk already decided that we should send one million people there to build a self-sustaining society, even though he himself admitted that he doesn't have any idea how to make that latter part work economically or technologically. That was half the point of his talk...

That's a quote from you, which avoids my question. When did Mush say he wouldn't wait for surface probe results?. Hint: he didn't.

So in your alternative plan all space exploration will be using theoretical propulsion that starts from this planet ... environmentally friendly and sustainable

Electric propulsion (various styles of ion engines and plasma engines) is not "theoretical" - it's in use today on space probes and even commercial satellites - unlike the deuterium-based fusion that your plans seem to depend upon. And yes, it is more environmentally friendly and sustainable because it's literally about ten times as fuel efficient as chemical rockets.

There are various good reasons why Musk didn't select electric propulsion for his proposal, but they mostly revolve around his fixation on putting tons of human beings on the surface of Mars. For mining the Main Belt, most of his reasons do not apply.

Present technology - with which I'm familiar (and not just from reading /.) is too slow for human transport - but viable for unmanned (or short manned) transport.

I guess that'll push up the price aluminium, good plan

??? What does this have to do with anything I said? Electric engines can run on pretty much any elemental propellant (as long as it's not too reactive), including abundant hydrogen, or any of the noble gases. My proposal almost certainly uses less aluminium than Musk's, since it requires less total up-mass and aerospace stuff tends to use a lot of aluminium for structural purposes.

[sigh]Musk's transports are resusable - what are you wrapping your (imaginary) rockets in? Unicorn farts?

I'm somewhat familiar with large scale mining and I find your remote mining of asteroids "controlled from Earth, intriguing. I wonder why we don't do that now instead of FIFO to humpies in the Pilbara??

Are you really that clueless that you don't understand that Pilbara is an orders of magnitude cheaper place to send and sustain human life than any asteroid, or Mars?

The more expensive it is to send people to the job site, and keep them alive once they get there, the higher the economic incentive to figure out how to automate the job. Many jobs that could be done most cheaply by people on Earth are cheaper with automation in space.

True - to a point. The point where armchair speculation about what the percentage of gearing ratio is onsite labour in the Pilbara, meets reality (it's around 70%). It's enourmously expensive to fly workers in and out and house them in the Pilbara - it's much cheaper to mine remotely (it's been tried, and we'll keep trying). And we'd do it if it saved only a few hundred thousand - but things go wrong (always) - it's still cheaper to send (extra) engineers and workers in only when things go wrong, but the cost of interrupted production is the reason why we don't do it. tl;dr? We don't remotely mine the Pilbara because it's not signficantly cheaper - it's because interruption to the supply chain is a much higher cost. That's not theory or conjecture - there in lies the difference of "opinion".
I'm "guessing" that with limited launch windows from Earth available to workers and engineers that would need to be sent to fix things if remote asteroid mining go - and much longer production chains, that real life factor would increase. From an armchair it may sound cheaper to send remote mining equipment to asteroids - but in real life it'd be a poor investment.

And it's not like there are any viable alternatives

The viable alternative is to stay on Earth unless and until we have the technology to establish a truly self-sustaining, or otherwise economically viable, colony elsewhere.

[cough] That's not an "alternative" (therefore it cannot be "viable") - it's just the (current) situation. Until we develop (and test) the required technology (if it's possible).

Musk himself already admitted in his presentation that we don't have that tech today; he's just hoping someone else will invent it before the ITS is ready.

Where's the problem with that (especially seeing as someone else may be employed by him)??

Why is he doing this? Because he knows he'll probably die within a few decades, at most, and he's impatient enough that he can't stand just waiting for the tech to mature.

Was there a point to that statement?

(Note that I am arguing against premature large-scale colonization, not exploration or technology development. Sending some people to visit Mars soon is a reasonable goal; sending a million to stay probably isn't.)

I suspect he's not serious about making the primary mission to populate Mars with a million people. If it's possible to send return robot missions to Mars (and land) - then the technological advancements will be of enormous value, and, it would make the scenario he describes worthwhile doing (because we can do useful work there). More worthwhile than a similar mission to the Moon (the space equivalent of a mission to Easter Island).

I believe Elon is correct in thinking he can find passengers that will pay for the opportunity - you seem to be arguing that his idea doesn't serve your agenda.

I think he's correct too, if he can achieve the super-low prices he claims. BUT, those prices only cover transportation - they don't cover all the stuff you need to stay alive once you get there, and SpaceX isn't even claiming to know what all that other stuff will cost.

Agreed. If he claimed he could price everything I'd be dumping Tesla shares this minute. Perhaps you've confused his speech with the launch of ticket sales....

Gravity is not a reason why it shouldn't be used

It absolutely is a reason not to use it as a trading post on the way to the Main Belt like you proposed. Gravity might or might not be a reason not to use Mars for the resources available on the surface - it depends on whether there's an easier place to get those same resources, instead (like Earth...).

Unless we re-engineer the human body any space colony will be short lived. With present technology (and resources), large scale mining of asteroids from Earth is not something I'd invest in (and I don't do /. armchair investing in mining). What you do with your investments, is your business.

Comment Re:No return trips? (Score 1) 497

Only a moron would jump the conclusion that it meant that all the development failures have to be marketed

The same can be said about people who try every desperate measure to defend Musk and SpaceX.

I agree. Though I'm not. However people who make shit up to try take every desparate measure to defame Musk and SpaceX are not just morons - they're a waste of space and oxygen. e.g. people whose invent things to support an unsupportable opinion ("I saw thousands of people cheering 911") - or you, when you bullshitted about what I quoted so that you could put a spin on things "Elon sells failure". When he does I'll damn him for it, likewise I would have damned lightbulbs that had filaments that lasted less than 2 seconds.

Comment Re:No return trips? (Score 1) 497

Then why did you use *that* analogy?

To point out the obvious to people who are not as recalcitrant as you - new technology is usually the result of repeated failure (iterative refinements). Only a moron would jump the conclusion that it meant that all the development failures have to be marketed - or a moron that's desperately trying to sustain an unsupportable position.

Comment Re:Consenting parties (Score 1) 497

you confuse

No. You're just confused - at best. In a discussion about the viability of a Mars Mission you repeatedly inject irrelevant "information" and try and present it as relevant. As you have just done. Trying to impress by baffling with bullshit might have worked in pre-school but you're not there now (I hope).

And I don't "attempt" to insult anyone.

Comment Re:1Million People (Score 1) 497

Deuterium

As far as I can tell, the worldwide deuterium market is currently less than $2 billion per year,

Not because of De Beers type cartel - simply because it's extremely rare on Earth.
tl:dr? $2 Billion is not the limit of demand, it's the limit of supply. I guess that's a mistake any business amateur could make.

whereas Musk's plan proposes to spend at least $10 billion per year on transportation alone - and obviously there would be many other large costs associated with establishing a self-sufficient mining colony.

You asked for something that's more plentiful on Mars than on Earth - so stop lugging those goal posts over to where Deuterium is the sole reason for going there. A transport cost that is less than one tenth of what the USA spends annually on the bullshit War on Drugs is a not a good reason - even if you phrase it like it's an ongoing cost (or like it's coming out of your welfare cheque).

I doubt Mars has much at all in resources that would fund the trips there - that's why I refered to it as a trading post. Eventually it's resources will produce funds from Earth - but it's unlikely they'd ever pay for the initial trips - what it does have is location and resources that will make it an important (critical) staging station for mining the Main Belt. What little we know about Mars is that it has lots of Deuterium. It can be used for more than just electricity production, which given Martian winds is probably not the first choice for power generation - and the viability of the process can not be measured by Earth criteria. Tritium is not abundant - but places you could cheaply and easily produce it are. Just a guess - the two would be of value for fueling fusion rockets.

When your largest resource is water a 5x greater abundance of deuterium, on a mostly unpopulated planet will be more than 5 times easier to refine - it's just a by-product of potable water production.

knowledge about the environment that we won't know until surface probes return results

Why not wait for those results before deciding that we should spend a trillion dollars on settling one million people there?

Red Herring alert! Can you point to the source of your claim that this fleet won't be waiting for results from surface probes (and many robotic test trips)?!

It's a strawman question (intentional?) that ignores viable access to the asteroids of the Main Belt ... it's not about the end-points, it's the points in-between - many of them inhospitable places. All of it driven by trade ...

It would be cheaper to skip the million-person Mars colony, and just focus on mining asteroids. Most (all?) of the work can be done automated with supervision from Earth. The Martian surface is an expensive distraction at the bottom of a deep gravity well. Refuelling at Mars is probably unnecessary with electric propulsion, but can be accomplished with way less than a million people there if needed.

So in your alternative plan all space exploration will be using theoretical propulsion that starts from this planet - presumably using rockets powered by environmentally friendly and sustainable unicorn gases (I guess that'll push up the price aluminium, good plan - we can mine more easily refineable aluminium ore from the moon). Moving a million to Mars is achievable - moving a billion is not. We don't have the resources for it, and environmental effects would have a severe impact on those that don't go.

I'd like to see your costing that shows why your "plan" is cheaper than Elon's - until then I'd just have to take your word for that you've "got it all figured out".

I'm somewhat familiar with large scale mining and I find your remote mining of asteroids "controlled from Earth, intriguing. I wonder why we don't do that now instead of FIFO to humpies in the Pilbara?? Surely it'd be cheaper... maybe it's a Union thing.

In the case of Australia colonisation was originally intended as a means of supporting and claiming a trading base

The Martian surface is not a good trading base for any destination but itself. The relatively deep gravity well means that it's not really "on the way" to anywhere else, delta-V wise. And, we don't need a million people there if the goal is just to supply fuel to stuff in orbit.

Agree it's not an ideal trading post - there isn't even a Pizza Hut there, but that's in keeping with the history of trading posts. And it's not like there are any viable alternatives - and no, the moon is not a viable alternative.

I believe Elon is correct in thinking he can find passengers that will pay for the opportunity - you seem to be arguing that his idea doesn't serve your agenda.

Gravity is not a reason why it shouldn't be used, for the same reason that the presence of water is not.

Comment Re:Consenting parties (Score 1) 497

The company who build the rocket has an obligation to disclose any known or reasonably foreseeable risks.

You've got a low enough /. ID number to be fully aware of the fact that salesmen and corporate executives lie on a distressingly regular basis.

And obviously a high enough IQ to have considered that - just like the company that buys the launch services, and the company that insures both parties.

Understandably you are unable to take that into consideration and thus depart on a tangential path to nowhere important overloaded with inconsequential "considerations".
[someone]"I think a black colour t-shirt will be warmer in the sun" [nutria] Black is not a colour, it will fade, the sun only shines during the day, you can't trust some t-shirt sellers, I had a really bad experience with a t-shirt (when I got my head stuck in the armhole) - four and a half good reasons why that is a bad idea (and there's no such thing as a bad argument). The sort of "logic" used by pro-Creationists - a large number of irrelevant but tenuously connected distractions from the subject in discussion (theys not irrellivent - they's all woody words).

Comment Re:They'll come crawling back (Score 1) 277

Their software works fine for me. Maybe the problem is you.

That's customer service right there. And Linux people wonder why their desktop market share can't break out of the bottom 1%...

Most of us don't care about "market share" or bullshit categories like "desktop market share". We just want what we use - phones, servers, routers, micro devices, planes, medical equipment, and even that small category of devices where Linux isn't the overwhelming OS of choice called "desktops" to work the way we want.
Most people have a phone, use the internet, watch television and use their pad devices far more than "Desktops" (even "Windows" fans who use Linux far more than Windows but are too dumb to realise it). We tend to leave the fan boi "brand loyalty" crap to face painters and other superstitious folk.

Just because thousand dollar handbags are pretty popular with reality TV stars doesn't mean most people want or use handbags - and if they do, they don't tend to give a fuck about the brand (it's just a tool, fool). Just as most people don't pay much attention to political, geographic, or racial boundaries - it just sounds that way because those that do, have time to make noise about it (except for dem commies - they're all de same - especially the 400lb Ruskie bedsitting "hackers").

Comment Re:1Million People (Score 1) 497

What can be made or mined on Mars that can't be made or mined more cheaply on Earth, or from asteroids?

Deuterium, knowledge - the latter is worth more than anything else. Likely lots of other valuable resources, mostly precious metals unavailable on a cooler Earth, mined out, and bio resources.

It's a strawman question (intentional?) that ignores viable access to the asteroids of the Main Belt, and precludes knowledge about the environment that we won't know until surface probes return results (we won't go to Madagascar/Orkney because legend has it there be dragons there).
Re-read the history of world trade and colonization - it's not about the end-points, it's the points in-between - many of them inhospitable places. All of it driven by trade (the rest are generally referred to as lost civilisations).

The European explorers and colonists to which you appeal went out in search of

I don't appeal to any explorers or colonists - they went where they were told they could.

What's now North America was originally considered of greatest value as a trading post for the West Indies - not as a (mythical) sanctuary for the religiously ostrasized. Colonization by non-government initiative had been happening for many centuries before on a trial and failure basis.

Australia has fuck all arable land by European standards - and almost all that "arable" soil is shallow has very little nutrients in it (it's in the landscape). European soil is deep and nutrient rich - the result of glacial activity. Except for two very small areas "arable" land in Australia is not of glacial origin (or the Chinese and Portugese would have settled centuries earlier). That's why Australian land is grossly overvalued and the first European settlers had such enormously high failure rates (the First Fleet starved). Australia has very little water, had lots of easily accessible gold, copper and other high demand metals - and is conveniently located near Java. Access to spices made it worthwhile establishing as a trade base, everything else was just a bonus (that the French would discovered as well if they'd been just a little quicker).

tl:dr? In the case of Australia colonisation was originally intended as a means of supporting and claiming a trading base - not as somewhere that had resources worth exploiting for exportation. The "we don't know where to put the convicts" story is a myth. "but - sheep!" didn't happen until George organised the theft of the Merino from Spain - much later, and "gold!" didn't happen until after the Californian strikes.

Comment Re:The Moon is first (Score 1) 497

And if America had been a minimum of 140 times farther away than the Arctic, that might have been a bit harder decision...

No. It's time, not distance - something to do with logistics, and whether you die from exposure and starvation at the destination - it's complicated (in your case).

Maybe if you asked Tim Severin he'd explain why Eric the Red or St Brendan sailed/paddled past the easier winds and currents to the Arctic instead of taking a direct flight on an Airbus like a fucking crow you might understand (something to do with why they managed to come back). Though I doubt there's much you do understand that doesn't involve Cheetos and an old sock.

Slashdot Top Deals

I have never seen anything fill up a vacuum so fast and still suck. -- Rob Pike, on X.

Working...