From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-io0-f199.google.com (mail-io0-f199.google.com [209.85.223.199]) by kanga.kvack.org (Postfix) with ESMTP id 58E86828E1 for ; Wed, 6 Jul 2016 02:49:32 -0400 (EDT) Received: by mail-io0-f199.google.com with SMTP id s63so454860330ioi.1 for ; Tue, 05 Jul 2016 23:49:32 -0700 (PDT) Received: from lgeamrelo11.lge.com (LGEAMRELO11.lge.com. [156.147.23.51]) by mx.google.com with ESMTP id j27si2232490ioi.109.2016.07.05.23.49.30 for ; Tue, 05 Jul 2016 23:49:31 -0700 (PDT) Date: Wed, 6 Jul 2016 15:50:16 +0900 From: Minchan Kim Subject: Re: [patch for-4.7] mm, compaction: prevent VM_BUG_ON when terminating freeing scanner Message-ID: <20160706065016.GA16614@bbox> References: MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline Sender: owner-linux-mm@kvack.org List-ID: To: David Rientjes Cc: Joonsoo Kim , Andrew Morton , linux-kernel@vger.kernel.org, linux-mm@kvack.org, hughd@google.com, mgorman@techsingularity.net, stable@vger.kernel.org, vbabka@suse.cz On Wed, Jun 29, 2016 at 02:47:20PM -0700, David Rientjes wrote: > It's possible to isolate some freepages in a pageblock and then fail > split_free_page() due to the low watermark check. In this case, we hit > VM_BUG_ON() because the freeing scanner terminated early without a > contended lock or enough freepages. > > This should never have been a VM_BUG_ON() since it's not a fatal > condition. It should have been a VM_WARN_ON() at best, or even handled > gracefully. > > Regardless, we need to terminate anytime the full pageblock scan was not > done. The logic belongs in isolate_freepages_block(), so handle its state > gracefully by terminating the pageblock loop and making a note to restart > at the same pageblock next time since it was not possible to complete the > scan this time. > > Reported-by: Minchan Kim > Signed-off-by: David Rientjes Tested-by: Minchan Kim I don't know you sill send updated version based on Joonsoo again. Anyway, this patch itself doesn't trigger VM_BUG_ON in my test. Thanks. -- 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