When dd in 512bytes, balance_dirty_pages_ratelimited() could be called 8 times for the same page, but obviously the page is only dirtied once. Fix it with a (slightly racy) PageDirty() test. Signed-off-by: Wu Fengguang <fengguang.wu@xxxxxxxxx> --- mm/filemap.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) --- linux-next.orig/mm/filemap.c 2011-03-02 14:18:52.000000000 +0800 +++ linux-next/mm/filemap.c 2011-03-02 14:20:07.000000000 +0800 @@ -2253,6 +2253,7 @@ static ssize_t generic_perform_write(str long status = 0; ssize_t written = 0; unsigned int flags = 0; + unsigned int dirty; /* * Copies from kernel address space cannot fail (NFSD is a big user). @@ -2301,6 +2302,7 @@ again: pagefault_enable(); flush_dcache_page(page); + dirty = PageDirty(page); mark_page_accessed(page); status = a_ops->write_end(file, mapping, pos, bytes, copied, page, fsdata); @@ -2327,7 +2329,8 @@ again: pos += copied; written += copied; - balance_dirty_pages_ratelimited(mapping); + if (!dirty) + balance_dirty_pages_ratelimited(mapping); } while (iov_iter_count(i)); -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>