<html><head><meta content="text/html; charset=us-ascii" http-equiv="Content-Type"></head><body><div><div style="font-family: Calibri,sans-serif; font-size: 11pt;">Really? Where did you learn this?<br><br>---<br>Sent using a tiny phone keyboard.<br>Apologies for any typos and autocorrect.<br>Also, this old phone only supports top post. Apologies.<br><br>Cy Schubert<br><Cy.Schubert@cschubert.com> or <cy@freebsd.org><br>The need of the many outweighs the greed of the few.<br>---<br></div></div><hr><span style="font-family: Tahoma,sans-serif; font-size: 10pt; font-weight: bold;">From: </span><span style="font-family: Tahoma,sans-serif; font-size: 10pt;">Alan W. Irwin</span><br><span style="font-family: Tahoma,sans-serif; font-size: 10pt; font-weight: bold;">Sent: </span><span style="font-family: Tahoma,sans-serif; font-size: 10pt;">29/01/2018 18:10</span><br><span style="font-family: Tahoma,sans-serif; font-size: 10pt; font-weight: bold;">To: </span><span style="font-family: Tahoma,sans-serif; font-size: 10pt;">Cy Schubert</span><br><span style="font-family: Tahoma,sans-serif; font-size: 10pt; font-weight: bold;">Cc: </span><span style="font-family: Tahoma,sans-serif; font-size: 10pt;">discuss@vlug.org</span><br><span style="font-family: Tahoma,sans-serif; font-size: 10pt; font-weight: bold;">Subject: </span><span style="font-family: Tahoma,sans-serif; font-size: 10pt;">RE: [Discuss] I need a recommendation for a Linux-compatible high-endPCbuilder</span><br><br>On 2018-01-29 15:25-0800 Cy Schubert wrote:<br><br>> What is special kernel memory?<br><br>It is memory whose size is a multiple of a set of particular discrete<br>sizes that are especially suitable for certain kernel uses. I cannot<br>remember exactly, but there were roughly 10 kinds of this kind of<br>special memory (each with a different base size to be used as the<br>multiple). Obviously the kernel could have just used ordinary malloc<br>and free with multiples of these special sizes when it needed memory.<br>But instead (presumably for efficiency reasons) the Linux kernel from<br>3 years ago defined a fixed area of ordinary memory and used its own<br>special routines for allocating and freeing the specially sized memory<br>blocks of the various kinds within that fixed region.<br><br>> What is a special type of memory leak?<br><br>Just like an ordinary memory leak only for each kind of special memory.<br>One example would be when the kernel has a loop that does a special<br>kind of such memory allocation without a corresponding special free.<br>So in my case the size of one of those specially allocated areas<br>started small after a boot but constantly grew as time progressed<br>according to /sys/kernel information.<br><br>> Are you suggesting that the Linux kernel is particularly unstable?<br><br>Nope. But the above idea (which was definitely part of the Linux kernel<br>from three years ago) has some obvious special memory handling<br>requirements for each kind of special memory in complete analogy with<br>ordinary memory management. So there are possibilities for such<br>memory management screwups for each kind of special memory. In my<br>case I discovered such a kernel issue with just one special kind of<br>memory. But it must have been a corner case because the Debian<br>kernel developers could not reproduce it.<br><br>> Are you sure it's JavaScript that is the issue or could it be Java?<br><br>I note for the others here this is a completely different topic then the above<br>special memory leak issues you asked me about above. And the answer to<br>your question is javascript. Do a google search for the terms<br>javascript memory leak and you will find lots of references. Add<br>"theweathernetwork" to that search and you will find<br><https://forums.informaction.com/viewtopic.php?f=10&t=21675> which<br>gives a clear example.<br><br>If JavaScript, are you suggesting that Firefox is unstable?<br><br>No more than other browsers, but historically they have all been much<br>too trustful of javascript. Thus, javascript code that your browser<br>encounters when you browse a malicious website provides a huge<br>opportunity for security attacks against your operating system. <br>That's why javascript is mentioned so much in articles discussing the<br>Spectre variant 2 vulnerability, and part of the mitigation for that<br>vulnerability must include hardening of all the browsers against bad<br>javascript code. That process is obviously ongoing, but it takes time.<br>So for now the suggestion I have read several places is to always use<br>the noscript extension to firefox and similar whitelist measures for<br>other browsers. Side benefits of such whitelist measures are<br>typically ads disappear (if you don't allow domains that generate ads<br>on your javascript code source whitelist) and the chances of<br>javascript-related memory leaks are also obviously reduced by simply<br>reducing the domains that you use for javascript.<br><br>For example, the above Weather Network user used the firefox nolist<br>extension to isolate a javascript-related memory leak in the<br>javascript code generated by the legitimate domain twnmm.com.<br>According to the discussion, twnmm.com had a horrific javascript code<br>screwup in the code they were sending to all users who were browsing<br>The Weather Network and presumably users of any other website that<br>uses javascript code distributed by twnmm.com in the same way. But<br>presumably twnmm.com have long-since fixed up that javascript bug<br>because the google utility (conveniently accessible from nolist with a<br>middle click) for evaluating the legitimacy of javascript code<br>produced by a given domain gives twnmm.com a clean bill of health, and<br>when I allowed twnmm.com on my whitelist, no memory leaks resulted and<br>I got obviously improved graphics file capability for the The Weather<br>Network (although there is still some site I am missing from my<br>whitelist that is required to make that fully work).<br><br>Anyhow, I suggest those here who use firefox and are currently not<br>aware of the nolist extension to that browser should try it<br>immediately for enhanced security (especially appropriate when<br>javascript attacks via Spectre are presumably on the upsurge),<br>reduction of ads, and reduction of chances for javascript memory<br>leaks.<br><br>Alan<br><br>__________________________<br>Alan W. Irwin<br><br>Astronomical research affiliation with Department of Physics and Astronomy,<br>University of Victoria (astrowww.phys.uvic.ca).<br><br>Programming affiliations with the FreeEOS equation-of-state<br>implementation for stellar interiors (freeeos.sf.net); the Time<br>Ephemerides project (timeephem.sf.net); PLplot scientific plotting<br>software package (plplot.sf.net); the libLASi project<br>(unifont.org/lasi); the Loads of Linux Links project (loll.sf.net);<br>and the Linux Brochure Project (lbproject.sf.net).<br>__________________________<br><br>Linux-powered Science<br>__________________________<br><br></body></html>