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 2011-04-13 16:46:01.000000000 +0800 +++ linux-next/mm/filemap.c 2011-04-13 16:47:26.000000000 +0800 @@ -2313,6 +2313,7 @@ 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). @@ -2361,6 +2362,7 @@ 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); @@ -2387,7 +2389,8 @@ again: pos += copied; written += copied; - balance_dirty_pages_ratelimited(mapping); + if (!dirty) + balance_dirty_pages_ratelimited(mapping); } while (iov_iter_count(i)); -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
