On Wed, 8 Mar 2006, Luck, Tony wrote: > Thinking about this further ... in most cases the swap path will also > conceal any evidence that this happened, because it will overwrite > the pte with the swap file number and offset of where it stashed > the page ... so "we've been lucky for all these years" theory is > looking quite credible. Hmm.... What happens for the dirty bit .... zero pte is marked dirty, however page is marked not present, thus page fault follows. By the time the fault handler checks the pte it is valid again since the swapper overwrote with a swap pte (otherwise we would get VM: killing process ...), swapper overwrites with swap pte. The fault is a write fauklt which restores the page and marks it dirty. Then the process writes to the page. So that seems to be okay. But this only occurs for anonymous pages. If the page is file backed and zapped by the swapper then the pte is not rewritten again but the fault handler tries to "interpret" the strange pte. - : send the line "unsubscribe linux-ia64" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
|