On Sunday 02 October 2005 03:03, Jeff Dike wrote: > On Thu, Sep 29, 2005 at 02:09:27PM +0200, Blaisorblade wrote: > > Again, that page is not bad. There is no page yet for this address, and > > the host won't allocate one for now.
> It is bad in the sense that, unless some space is freed on that mount, a > reference to the page will always fault. Sorry, any reference will fault, unless it is done on a allocated present page, which the UML kernel freed but the host didn't. And remember, btw, you've planned to make this impossible... > > Ok, this makes a bit of sense, even if IMHO it doesn't work, I now see > > your point (but I still insist with what said above). > Explain why it doesn't work. Below. > > However, even a dirtied page could be "bad", if it has been swapped. If > > we're getting a SIGBUS, it meant that it didn't succeed in freeing any > > memory. > No it can't. A swapped page still counts as occupying space in the > filesystem. If a page was successfully allocated, then accesses to it will > always succeed, even if it needs to be swapped in. Sorry, Jeff, which page are you going to evict? It can be a dirty page. Unless you mean that since that page is still accounted in the FS, Linux will leave a RAM page free to allow it to be re-read, while still swapping the page. You didn't obviously mean this absurdity (why swap it in first place), but I don't catch what's missing to you. > > And, frankly, unless the UML ram file is kept on ramfs (which is > > RAM-only), it can be swapped (both for disk-based filesystem and for > > tmpfs). So, I don't think what you suggest could work. > Swapping makes no difference. Realoding pages means freeing RAM to leave place to them. -- Inform me of my mistakes, so I can keep imitating Homer Simpson's "Doh!". Paolo Giarrusso, aka Blaisorblade (Skype ID "PaoloGiarrusso", ICQ 215621894) http://www.user-mode-linux.org/~blaisorblade ___________________________________ Yahoo! Messenger: chiamate gratuite in tutto il mondo http://it.messenger.yahoo.com ------------------------------------------------------- This SF.Net email is sponsored by: Power Architecture Resource Center: Free content, downloads, discussions, and more. http://solutions.newsforge.com/ibmarch.tmpl _______________________________________________ User-mode-linux-devel mailing list User-mode-linux-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/user-mode-linux-devel
