The patch titled
do_wp_page: clarify dirty_page handling
has been added to the -mm tree. Its filename is
do_wp_page-clarify-dirty_page-handling.patch
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------------------------------------------------------
Subject: do_wp_page: clarify dirty_page handling
From: Michel Lespinasse <walken@xxxxxxxxxx>
Reorganize the code so that dirty pages are handled closer to the place
that makes them dirty (handling write fault into shared, writable VMAs).
No behavior changes.
Signed-off-by: Michel Lespinasse <walken@xxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxx>
Cc: Kosaki Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Nick Piggin <npiggin@xxxxxxxxx>
Cc: Theodore Tso <tytso@xxxxxxxxxx>
Cc: Michael Rubin <mrubin@xxxxxxxxxx>
Cc: Suleiman Souhlal <suleiman@xxxxxxxxxx>
Cc: Dave Chinner <david@xxxxxxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/memory.c | 72 ++++++++++++++++++++++++++------------------------
1 file changed, 38 insertions(+), 34 deletions(-)
diff -puN mm/memory.c~do_wp_page-clarify-dirty_page-handling mm/memory.c
--- a/mm/memory.c~do_wp_page-clarify-dirty_page-handling
+++ a/mm/memory.c
@@ -2251,8 +2251,45 @@ reuse:
entry = maybe_mkwrite(pte_mkdirty(entry), vma);
if (ptep_set_access_flags(vma, address, page_table, entry,1))
update_mmu_cache(vma, address, page_table);
+ pte_unmap_unlock(page_table, ptl);
ret |= VM_FAULT_WRITE;
- goto unlock;
+
+ if (!dirty_page)
+ return ret;
+
+ /*
+ * Yes, Virginia, this is actually required to prevent a race
+ * with clear_page_dirty_for_io() from clearing the page dirty
+ * bit after it clear all dirty ptes, but before a racing
+ * do_wp_page installs a dirty pte.
+ *
+ * do_no_page is protected similarly.
+ */
+ if (!page_mkwrite) {
+ wait_on_page_locked(dirty_page);
+ set_page_dirty_balance(dirty_page, page_mkwrite);
+ }
+ put_page(dirty_page);
+ if (page_mkwrite) {
+ struct address_space *mapping = dirty_page->mapping;
+
+ set_page_dirty(dirty_page);
+ unlock_page(dirty_page);
+ page_cache_release(dirty_page);
+ if (mapping) {
+ /*
+ * Some device drivers do not set page.mapping
+ * but still dirty their pages
+ */
+ balance_dirty_pages_ratelimited(mapping);
+ }
+ }
+
+ /* file_update_time outside page_lock */
+ if (vma->vm_file)
+ file_update_time(vma->vm_file);
+
+ return ret;
}
/*
@@ -2358,39 +2395,6 @@ gotten:
page_cache_release(old_page);
unlock:
pte_unmap_unlock(page_table, ptl);
- if (dirty_page) {
- /*
- * Yes, Virginia, this is actually required to prevent a race
- * with clear_page_dirty_for_io() from clearing the page dirty
- * bit after it clear all dirty ptes, but before a racing
- * do_wp_page installs a dirty pte.
- *
- * do_no_page is protected similarly.
- */
- if (!page_mkwrite) {
- wait_on_page_locked(dirty_page);
- set_page_dirty_balance(dirty_page, page_mkwrite);
- }
- put_page(dirty_page);
- if (page_mkwrite) {
- struct address_space *mapping = dirty_page->mapping;
-
- set_page_dirty(dirty_page);
- unlock_page(dirty_page);
- page_cache_release(dirty_page);
- if (mapping) {
- /*
- * Some device drivers do not set page.mapping
- * but still dirty their pages
- */
- balance_dirty_pages_ratelimited(mapping);
- }
- }
-
- /* file_update_time outside page_lock */
- if (vma->vm_file)
- file_update_time(vma->vm_file);
- }
return ret;
oom_free_new:
page_cache_release(new_page);
_
Patches currently in -mm which might be from walken@xxxxxxxxxx are
do_wp_page-remove-the-reuse-flag.patch
do_wp_page-clarify-dirty_page-handling.patch
mlock-avoid-dirtying-pages-and-triggering-writeback.patch
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