From mboxrd@z Thu Jan 1 00:00:00 1970 Subject: [RFC][PATCH] mm: balance_dirty_pages() vs throttle_vm_writeout() deadlock From: Peter Zijlstra Content-Type: text/plain Date: Tue, 20 Feb 2007 16:49:24 +0100 Message-Id: <1171986565.23046.5.camel@twins> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: linux-mm@kvack.org Cc: Trond Myklebust , Andrew Morton List-ID: If we have a lot of dirty memory and hit the throttle in balance_dirty_pages() we (potentially) generate a lot of writeback and unstable pages, if however during this writeback we need to reclaim a bit, we might hit throttle_vm_writeout(), which might delay us until the combined total of NR_UNSTABLE_NFS + NR_WRITEBACK falls below the dirty limit. However unstable pages don't go away automagickally, they need a push. While balance_dirty_pages() does this push, throttle_vm_writeout() doesn't. So we can sit here ad infintum. Hence I propose to remove the NR_UNSTABLE_NFS count from throttle_vm_writeout(). Signed-off-by: Peter Zijlstra --- mm/page-writeback.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) Index: linux-2.6-git/mm/page-writeback.c =================================================================== --- linux-2.6-git.orig/mm/page-writeback.c 2007-02-20 15:07:43.000000000 +0100 +++ linux-2.6-git/mm/page-writeback.c 2007-02-20 16:42:45.000000000 +0100 @@ -310,8 +310,7 @@ void throttle_vm_writeout(void) */ dirty_thresh += dirty_thresh / 10; /* wheeee... */ - if (global_page_state(NR_UNSTABLE_NFS) + - global_page_state(NR_WRITEBACK) <= dirty_thresh) + if (global_page_state(NR_WRITEBACK) <= dirty_thresh) break; congestion_wait(WRITE, HZ/10); } -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org