Commit 3e67c098 authored Dec 21, 2006 by Andrew Morton Committed by Linus Torvalds Dec 21, 2006

[PATCH] truncate: clear page dirtiness before running try_to_free_buffers()



truncate presently invalidates the dirty page's buffer_heads then shoots down
the page.  But try_to_free_buffers() will now bale out because the page is
dirty.

Net effect: the LRU gets filled with dirty pages which have invalidated
buffer_heads attached.  They have no ->mapping and hence cannot be cleaned.
The machine leaks memory at an enormous rate.

Fix this by cleaning the page before running try_to_free_buffers(), so
try_to_free_buffers() can do its work.

Also, remember to do dirty-page-acoounting in cancel_dirty_page() so the
machine won't wedge up trying to write non-existent dirty pages.

Probably still wrong, but now less so.

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

parent 92132021

mm/truncate.c

+5 −4

Original line number	Diff line number	Diff line
		@@ -60,10 +60,11 @@ void cancel_dirty_page(struct page *page, unsigned int account_size)
		WARN_ON(++warncount < 5);
		}

		if (TestClearPageDirty(page) && account_size)
		if (TestClearPageDirty(page) && account_size) {
		dec_zone_page_state(page, NR_FILE_DIRTY);
		task_io_account_cancelled_write(account_size);
		}

		}

		/*
		* If truncate cannot remove the fs-private metadata from the page, the page
		@@ -81,11 +82,11 @@ truncate_complete_page(struct address_space mapping, struct page page)
		if (page->mapping != mapping)
		return;

		cancel_dirty_page(page, PAGE_CACHE_SIZE);

		if (PagePrivate(page))
		do_invalidatepage(page, 0);

		cancel_dirty_page(page, PAGE_CACHE_SIZE);

		ClearPageUptodate(page);
		ClearPageMappedToDisk(page);
		remove_from_page_cache(page);