From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qc0-f180.google.com (mail-qc0-f180.google.com [209.85.216.180]) by kanga.kvack.org (Postfix) with ESMTP id 6D37E6B0038 for ; Tue, 18 Nov 2014 21:48:16 -0500 (EST) Received: by mail-qc0-f180.google.com with SMTP id i8so8788749qcq.11 for ; Tue, 18 Nov 2014 18:48:16 -0800 (PST) Received: from mx1.redhat.com (mx1.redhat.com. [209.132.183.28]) by mx.google.com with ESMTPS id q110si525021qgd.122.2014.11.18.18.48.13 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 18 Nov 2014 18:48:15 -0800 (PST) Message-ID: <546C04E0.4090209@redhat.com> Date: Tue, 18 Nov 2014 21:48:00 -0500 From: Rik van Riel MIME-Version: 1.0 Subject: Re: [PATCH] Repeated fork() causes SLAB to grow without bound References: <502D42E5.7090403@redhat.com> <20120818000312.GA4262@evergreen.ssec.wisc.edu> <502F100A.1080401@redhat.com> <20120822032057.GA30871@google.com> <50345232.4090002@redhat.com> <20130603195003.GA31275@evergreen.ssec.wisc.edu> <20141114163053.GA6547@cosmos.ssec.wisc.edu> <20141117160212.b86d031e1870601240b0131d@linux-foundation.org> <20141118014135.GA17252@cosmos.ssec.wisc.edu> <546AB1F5.6030306@redhat.com> <20141118121936.07b02545a0684b2cc839a10c@linux-foundation.org> In-Reply-To: <20141118121936.07b02545a0684b2cc839a10c@linux-foundation.org> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: Michel Lespinasse , Hugh Dickins , Andrea Arcangeli , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Tim Hartrick , Michal Hocko -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On 11/18/2014 03:19 PM, Andrew Morton wrote: > On Mon, 17 Nov 2014 21:41:57 -0500 Rik van Riel > wrote: > >> That way people can understand what the code does simply by >> looking at the changelog - no need to go find old linux-kernel >> mailing list threads. > > Yes please, there's a ton of stuff here which we should attempt to > capture. > > https://lkml.org/lkml/2012/8/15/765 is useful. > > I'm assuming that with the "foo < 5" hack, an application which > forked 5 times then did a lot of work would still trigger the > "catastrophic issue at page reclaim time" issue which Rik > identified at https://lkml.org/lkml/2012/8/20/265? It's not "forking 5 times", it is "forking >>5 generations deep". There are a few programs that do that, but it does not appear that they are forking servers like apache or sendmail (which fork from the 2nd generation, and then sometimes again to exec a helper from the 4th generation). > There are real-world workloads which are triggering this slab > growth problem, yes? (Detail them in the changelog, please). There are, but the overlap between "forks >>5 generations deep" and "forks a bajillion child processes" appears to be zero. - -- All rights reversed -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQEcBAEBAgAGBQJUbATgAAoJEM553pKExN6Ds84H/ixCr4Q5C09sDISuw9y/PsVI moXPbqgefpzbS316MgD1AMl7rj2OWAMiQcRGQ6yMelXOyuB89XTiBi19t5UxaSUn tuFnxeknoIL0155yTfszETRGjN9mUKoyk9HAhND1T+x2VFLwaQYyk7CdZC/h7IQ7 m1jfwlR30r0Ie6x5lkN1XaculdWdXjr7wTwUWeOVsc6lWv3kR3dC52LKsB4fv340 gBeL5sTDNNp6r5Gfr5QL7fQR0eLVvhStSmsm4GbggpVSBSCpZ++h8eTjdtHxuJO3 jtgEGAvhnLDSqRi6NG6dKoxtXW8++hnFIKBw1Ec36NTuTkbKiHo9EQujINtXWro= =/EU5 -----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