Messages in this thread | | | Date | Wed, 3 Nov 2004 00:12:27 +0100 | From | Andrea Arcangeli <> | Subject | Re: fix iounmap and a pageattr memleak (x86 and x86-64) |
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On Tue, Nov 02, 2004 at 05:34:08PM -0500, Jason Baron wrote: > I've seen the page_count being -1 (not sure why), for a number of pages in > the identity mapped region...So the BUG() on 0 doesn't seem valid to me.
bugcheck on 0 is valid there, it signals memleak. page_count == -1 signals another bug that might or might not be fixed by this as far as I can tell (this furthermore is a pte, so it sure can't have page_count == 0 or -1). So please try to track down which pages had page_count == -1.
Note, we must not confuse page->count with page_count, for the former value -1 means "in the freelist". For the latter it signals a bug.
> Also, in order to tell if the pages should be merged back to create a huge > page, i don't see how the patch differentiates b/w pages that were split > and those that weren't simply based on the page_count....
that's a page_count of the _pte_, not of the pages. so we're guaranteed it's always 1 unless we deal with this very pageattr code that is the only one that evers boost a pte page_count to > 1.
If you mean how can we provide an universal API with only keeping track of things with the page_count of the pte, we can't, and that's why it's not an universal API and that's why some symmetry is required by the API. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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