[PATCH] page migration: Fix MPOL_INTERLEAVE behavior for migration via mbind() (1e275d40) · Commits · 戴 / test

migrate_pages_to() allocates a list of new pages on the intended target node or with the intended policy and then uses the list of new pages as targets for the migration of a list of pages out of place. When the pages are allocated it is not clear which of the out of place pages will be moved to the new pages. So we cannot specify an address as needed by alloc_page_vma(). This causes problem for MPOL_INTERLEAVE which will currently allocate the pages on the first node of the set. If mbind is used with vma that has the policy of MPOL_INTERLEAVE then the interleaving of pages may be destroyed. This patch fixes that by generating a fake address for each alloc_page_vma which will result is a distribution of pages as prescribed by MPOL_INTERLEAVE. Lee also noted that the sequence of nodes for the new pages seems to be inverted. So we also invert the way the lists of pages for migration are build. Signed-off-by:

Christoph Lameter <clameter@sgi.com> Signed-off-by:

Lee Schermerhorn <lee.schermerhorn@hp.com> Looks-ok-to: Andi Kleen <ak@suse.de> Signed-off-by:

Andrew Morton <akpm@osdl.org> Signed-off-by:

Linus Torvalds <torvalds@osdl.org>

mm/mempolicy.c

+18 −4

Original line number	Diff line number	Diff line
		@@ -552,7 +552,7 @@ static void migrate_page_add(struct page page, struct list_head pagelist,
		*/
		if ((flags & MPOL_MF_MOVE_ALL) \|\| page_mapcount(page) == 1) {
		if (isolate_lru_page(page))
		list_add(&page->lru, pagelist);
		list_add_tail(&page->lru, pagelist);
		}
		}

		@@ -569,6 +569,7 @@ static int migrate_pages_to(struct list_head *pagelist,
		LIST_HEAD(moved);
		LIST_HEAD(failed);
		int err = 0;
		unsigned long offset = 0;
		int nr_pages;
		struct page *page;
		struct list_head *p;
		@@ -576,8 +577,21 @@ static int migrate_pages_to(struct list_head *pagelist,
		redo:
		nr_pages = 0;
		list_for_each(p, pagelist) {
		if (vma)
		page = alloc_page_vma(GFP_HIGHUSER, vma, vma->vm_start);
		if (vma) {
		/*
		* The address passed to alloc_page_vma is used to
		* generate the proper interleave behavior. We fake
		* the address here by an increasing offset in order
		* to get the proper distribution of pages.
		*
		* No decision has been made as to which page
		* a certain old page is moved to so we cannot
		* specify the correct address.
		*/
		page = alloc_page_vma(GFP_HIGHUSER, vma,
		offset + vma->vm_start);
		offset += PAGE_SIZE;
		}
		else
		page = alloc_pages_node(dest, GFP_HIGHUSER, 0);

		@@ -585,7 +599,7 @@ redo:
		err = -ENOMEM;
		goto out;
		}
		list_add(&page->lru, &newlist);
		list_add_tail(&page->lru, &newlist);
		nr_pages++;
		if (nr_pages > MIGRATE_CHUNK_SIZE)
		break;

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