The patch titled
page migration cleanup: extract try_to_unmap from migration functions
has been removed from the -mm tree. Its filename is
page-migration-cleanup-extract-try_to_unmap-from-migration-functions.patch
This patch was dropped because it was merged into mainline or a subsystem tree
------------------------------------------------------
Subject: page migration cleanup: extract try_to_unmap from migration functions
From: Christoph Lameter <clameter@xxxxxxx>
Extract try_to_unmap and rename remove_references -> move_mapping
try_to_unmap() may significantly change the page state by for example setting
the dirty bit. It is therefore best to unmap in migrate_pages() before
calling any migration functions.
migrate_page_remove_references() will then only move the new page in place of
the old page in the mapping. Rename the function to
migrate_page_move_mapping().
This allows us to get rid of the special unmapping for the fallback path.
Signed-off-by: Christoph Lameter <clameter@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
---
mm/migrate.c | 76 +++++++++++++++++++------------------------------
1 file changed, 31 insertions(+), 45 deletions(-)
diff -puN mm/migrate.c~page-migration-cleanup-extract-try_to_unmap-from-migration-functions mm/migrate.c
--- a/mm/migrate.c~page-migration-cleanup-extract-try_to_unmap-from-migration-functions
+++ a/mm/migrate.c
@@ -166,15 +166,14 @@ retry:
}
/*
- * Remove references for a page and establish the new page with the correct
- * basic settings to be able to stop accesses to the page.
+ * Replace the page in the mapping.
*
* The number of remaining references must be:
* 1 for anonymous pages without a mapping
* 2 for pages with a mapping
* 3 for pages with a mapping and PagePrivate set.
*/
-static int migrate_page_remove_references(struct page *newpage,
+static int migrate_page_move_mapping(struct page *newpage,
struct page *page)
{
struct address_space *mapping = page_mapping(page);
@@ -183,35 +182,6 @@ static int migrate_page_remove_reference
if (!mapping)
return -EAGAIN;
- /*
- * Establish swap ptes for anonymous pages or destroy pte
- * maps for files.
- *
- * In order to reestablish file backed mappings the fault handlers
- * will take the radix tree_lock which may then be used to stop
- * processses from accessing this page until the new page is ready.
- *
- * A process accessing via a swap pte (an anonymous page) will take a
- * page_lock on the old page which will block the process until the
- * migration attempt is complete. At that time the PageSwapCache bit
- * will be examined. If the page was migrated then the PageSwapCache
- * bit will be clear and the operation to retrieve the page will be
- * retried which will find the new page in the radix tree. Then a new
- * direct mapping may be generated based on the radix tree contents.
- *
- * If the page was not migrated then the PageSwapCache bit
- * is still set and the operation may continue.
- */
- if (try_to_unmap(page, 1) == SWAP_FAIL)
- /* A vma has VM_LOCKED set -> permanent failure */
- return -EPERM;
-
- /*
- * Give up if we were unable to remove all mappings.
- */
- if (page_mapcount(page))
- return -EAGAIN;
-
write_lock_irq(&mapping->tree_lock);
radix_pointer = (struct page **)radix_tree_lookup_slot(
@@ -310,7 +280,7 @@ int migrate_page(struct page *newpage, s
BUG_ON(PageWriteback(page)); /* Writeback must be complete */
- rc = migrate_page_remove_references(newpage, page);
+ rc = migrate_page_move_mapping(newpage, page);
if (rc)
return rc;
@@ -349,7 +319,7 @@ int buffer_migrate_page(struct page *new
head = page_buffers(page);
- rc = migrate_page_remove_references(newpage, page);
+ rc = migrate_page_move_mapping(newpage, page);
if (rc)
return rc;
@@ -482,6 +452,33 @@ redo:
lock_page(newpage);
/*
+ * Establish swap ptes for anonymous pages or destroy pte
+ * maps for files.
+ *
+ * In order to reestablish file backed mappings the fault handlers
+ * will take the radix tree_lock which may then be used to stop
+ * processses from accessing this page until the new page is ready.
+ *
+ * A process accessing via a swap pte (an anonymous page) will take a
+ * page_lock on the old page which will block the process until the
+ * migration attempt is complete. At that time the PageSwapCache bit
+ * will be examined. If the page was migrated then the PageSwapCache
+ * bit will be clear and the operation to retrieve the page will be
+ * retried which will find the new page in the radix tree. Then a new
+ * direct mapping may be generated based on the radix tree contents.
+ *
+ * If the page was not migrated then the PageSwapCache bit
+ * is still set and the operation may continue.
+ */
+ rc = -EPERM;
+ if (try_to_unmap(page, 1) == SWAP_FAIL)
+ /* A vma has VM_LOCKED set -> permanent failure */
+ goto unlock_both;
+
+ rc = -EAGAIN;
+ if (page_mapped(page))
+ goto unlock_both;
+ /*
* Pages are properly locked and writeback is complete.
* Try to migrate the page.
*/
@@ -501,17 +498,6 @@ redo:
goto unlock_both;
}
- /* Make sure the dirty bit is up to date */
- if (try_to_unmap(page, 1) == SWAP_FAIL) {
- rc = -EPERM;
- goto unlock_both;
- }
-
- if (page_mapcount(page)) {
- rc = -EAGAIN;
- goto unlock_both;
- }
-
/*
* Default handling if a filesystem does not provide
* a migration function. We can only migrate clean
_
Patches currently in -mm which might be from clameter@xxxxxxx are
origin.patch
mm-remove-vm_locked-before-remap_pfn_range-and-drop-vm_shm.patch
page-migration-support-a-vma-migration-function.patch
allow-migration-of-mlocked-pages.patch
zoned-vm-counters-create-vmstatc-h-from-page_allocc-h.patch
zoned-vm-counters-basic-zvc-zoned-vm-counter-implementation.patch
zoned-vm-counters-basic-zvc-zoned-vm-counter-implementation-tidy.patch
zoned-vm-counters-convert-nr_mapped-to-per-zone-counter.patch
zoned-vm-counters-conversion-of-nr_pagecache-to-per-zone-counter.patch
zoned-vm-counters-remove-nr_file_mapped-from-scan-control-structure.patch
zoned-vm-counters-remove-nr_file_mapped-from-scan-control-structure-fix.patch
zoned-vm-counters-split-nr_anon_pages-off-from-nr_file_mapped.patch
zoned-vm-counters-zone_reclaim-remove-proc-sys-vm-zone_reclaim_interval.patch
zoned-vm-counters-conversion-of-nr_slab-to-per-zone-counter.patch
zoned-vm-counters-conversion-of-nr_pagetables-to-per-zone-counter.patch
zoned-vm-counters-conversion-of-nr_dirty-to-per-zone-counter.patch
zoned-vm-counters-conversion-of-nr_writeback-to-per-zone-counter.patch
zoned-vm-counters-conversion-of-nr_unstable-to-per-zone-counter.patch
zoned-vm-counters-conversion-of-nr_bounce-to-per-zone-counter.patch
zoned-vm-counters-remove-useless-struct-wbs.patch
cpuset-remove-extra-cpuset_zone_allowed-check-in-__alloc_pages.patch
corrections-to-memory-barrier-doc.patch
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