From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-yk0-f177.google.com (mail-yk0-f177.google.com [209.85.160.177]) by kanga.kvack.org (Postfix) with ESMTP id 3565B6B0038 for ; Thu, 12 Feb 2015 10:12:40 -0500 (EST) Received: by mail-yk0-f177.google.com with SMTP id 20so4742006yks.8 for ; Thu, 12 Feb 2015 07:12:40 -0800 (PST) Received: from mx1.redhat.com (mx1.redhat.com. [209.132.183.28]) by mx.google.com with ESMTPS id 16si5186312qab.57.2015.02.12.07.12.38 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 12 Feb 2015 07:12:39 -0800 (PST) Message-ID: <54DCC2DE.10503@redhat.com> Date: Thu, 12 Feb 2015 10:12:30 -0500 From: Rik van Riel MIME-Version: 1.0 Subject: Re: [PATCH] mm: fix negative nr_isolated counts References: <20150211130905.4b0d1809b0689ffd6e83d851@linux-foundation.org> <54DC61C6.10502@suse.cz> In-Reply-To: <54DC61C6.10502@suse.cz> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Vlastimil Babka , Andrew Morton , Hugh Dickins Cc: linux-mm@kvack.org, Joonsoo Kim , Rafael Aquini -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On 02/12/2015 03:18 AM, Vlastimil Babka wrote: > On 02/11/2015 10:09 PM, Andrew Morton wrote: >>> Fixes: edc2ca612496 ("mm, compaction: move pageblock checks up >>> from isolate_migratepages_range()") Signed-off-by: Hugh Dickins >>> Cc: stable@vger.kernel.org # v3.18+ >> >> And why -stable? What user-visible problem is the bug causing? >> > > Commit 35cd78156c "vmscan: throttle direct reclaim when too many > pages are isolated already" by Rik seems to have introduced this > congestion_wait() based on too_many_isolated(). The bug it was > fixing: > > "When way too many processes go into direct reclaim, it is possible > for all of the pages to be taken off the LRU. One result of this is > that the next process in the page reclaim code thinks there are no > reclaimable pages left and triggers an out of memory kill." > > So either this is now prevented by something else and > too_many_isolated() could go away, or we should restore its > functionality. Any idea, Rik? I don't think that bug is prevented. I have seen reports of OOM kills happening while the system still has a lot of reclaimable page cache pages. This might actually help explain that bug... - -- All rights reversed -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQEcBAEBAgAGBQJU3MLdAAoJEM553pKExN6DheAH/RgOqPr/HwzgaalKd2JcQcSx xuIL/AhjIf8SYIHO5TTr00lF6mMpXfLs6+7UzYlICYmJ+wA4jZ6MapfpqYH/nkYG tCS/8kMvH+rfkrUMp8NDz1od4Akp9w153xpA/6rmNrGTrcwXY9L4R2ANj30sJ9bw 5aRvwsYKAbGjXwJqDFbkR6UySthEZ8wPlOZpjJyhBoA9kMx+hP/Aka+qjYkiS7Ny DfMuEjaNl8dsFZuulc7olhKNSXLyQPNmZt+oQCfb82KH78r6qpH2mhIrRtTunY6z 9iLHrxRgN2j8ZtDPFVaxMWQ3CQlaBZgTigSx1p+MTYVq8nfUe2HhkBgs2EKuV18= =hWac -----END PGP SIGNATURE----- -- 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