Messages in this thread | | | Date | Wed, 9 Nov 2005 08:50:12 -0800 (PST) | From | Christoph Lameter <> | Subject | Re: [PATCH 5/8] Direct Migration V2: upgrade MPOL_MF_MOVE and sys_migrate_pages() |
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On Wed, 9 Nov 2005, KAMEZAWA Hiroyuki wrote:
> > We only allocate 256 pages which are on the newlist. If the newlist is empty > > but there are still pages that could be migrated (!list_empty(pagelist)) > > then we need to allocate more pages and call migrate_pages() again. > Ah, Okay. > > confirmation: > 1. Because mm->sem is held, there is no page-is-truncated/freed case.
The page is truncated/freed case is handled by migrate_pages(). The page is moved to the "moved" lists and then returned to the LRU. The functions putting a page back to the LRU will check the refcount and discard the page.
> 2. Because pages in pagelist are removed from zone's lru, kswapd and others > will not > find and unmap them. There is no page-is-swapedout-by-others case.
Right.
> So if all target pages are successfuly remvoed from pagelist, newlist must be > empty. > Right ?
It could be empty but there could be new pages left over because some pages were freed before we could move them or we were unable to migrate a page and fell back to swap for a particular page. We need to free the leftover pages then.
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