This is a slight cleanup, but, more importantly, it will let us
easily detect writes via mmap when the process is done writing
(e.g. munmaps, msyncs, fsyncs, or dies).
Signed-off-by: Andy Lutomirski <luto@xxxxxxxxxxxxxx>
---
include/linux/mm.h | 1 +
mm/memory-failure.c | 4 +---
mm/page-writeback.c | 16 ++++++++++++++--
mm/rmap.c | 9 ++++++---
4 files changed, 22 insertions(+), 8 deletions(-)
diff --git a/include/linux/mm.h b/include/linux/mm.h
index a44aa00..4c7e49b 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1037,6 +1037,7 @@ int redirty_page_for_writepage(struct writeback_control *wbc,
void account_page_dirtied(struct page *page, struct address_space *mapping);
void account_page_writeback(struct page *page);
int set_page_dirty(struct page *page);
+int set_page_dirty_from_pte(struct page *page);
int set_page_dirty_lock(struct page *page);
int clear_page_dirty_for_io(struct page *page);
diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 8b20278..ab5c3f4 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -892,9 +892,7 @@ static int hwpoison_user_mappings(struct page *p, unsigned long pfn,
mapping = page_mapping(hpage);
if (!(flags & MF_MUST_KILL) && !PageDirty(hpage) && mapping &&
mapping_cap_writeback_dirty(mapping)) {
- if (page_mkclean(hpage)) {
- SetPageDirty(hpage);
- } else {
+ if (!page_mkclean(hpage)) {
kill = 0;
ttu |= TTU_IGNORE_HWPOISON;
printk(KERN_INFO
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 830893b..cdea11a 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -2109,6 +2109,19 @@ int set_page_dirty(struct page *page)
EXPORT_SYMBOL(set_page_dirty);
/*
+ * Dirty a page due to the page table dirty bit.
+ *
+ * For pages with a mapping this should be done under the page lock.
+ * This does set_page_dirty plus extra work to account for the fact that
+ * the kernel was not notified when the actual write was done.
+ */
+int set_page_dirty_from_pte(struct page *page)
+{
+ /* Doesn't do anything interesting yet. */
+ return set_page_dirty(page);
+}
+
+/*
* set_page_dirty() is racy if the caller has no reference against
* page->mapping->host, and if the page is unlocked. This is because another
* CPU could truncate the page off the mapping and then free the mapping.
@@ -2175,8 +2188,7 @@ int clear_page_dirty_for_io(struct page *page)
* as a serialization point for all the different
* threads doing their things.
*/
- if (page_mkclean(page))
- set_page_dirty(page);
+ page_mkclean(page);
/*
* We carefully synchronise fault handlers against
* installing a dirty pte and marking the page dirty
diff --git a/mm/rmap.c b/mm/rmap.c
index 2ee1ef0..b8fe00e 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -931,6 +931,9 @@ int page_mkclean(struct page *page)
ret = page_mkclean_file(mapping, page);
}
+ if (ret)
+ set_page_dirty_from_pte(page);
+
return ret;
}
EXPORT_SYMBOL_GPL(page_mkclean);
@@ -1151,7 +1154,7 @@ void page_remove_rmap(struct page *page)
*/
if (mapping && !mapping_cap_account_dirty(mapping) &&
page_test_and_clear_dirty(page_to_pfn(page), 1))
- set_page_dirty(page);
+ set_page_dirty_from_pte(page);
/*
* Hugepages are not counted in NR_ANON_PAGES nor NR_FILE_MAPPED
* and not charged by memcg for now.
@@ -1229,7 +1232,7 @@ int try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
/* Move the dirty bit to the physical page now the pte is gone. */
if (pte_dirty(pteval))
- set_page_dirty(page);
+ set_page_dirty_from_pte(page);
/* Update high watermark before we lower rss */
update_hiwater_rss(mm);
@@ -1423,7 +1426,7 @@ static int try_to_unmap_cluster(unsigned long cursor, unsigned int *mapcount,
/* Move the dirty bit to the physical page now the pte is gone. */
if (pte_dirty(pteval))
- set_page_dirty(page);
+ set_page_dirty_from_pte(page);
page_remove_rmap(page);
page_cache_release(page);
--
1.7.11.7
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