From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7ED4DC3A59B for ; Mon, 19 Aug 2019 09:03:49 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 3110A20989 for ; Mon, 19 Aug 2019 09:03:48 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3110A20989 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 847B36B0007; Mon, 19 Aug 2019 05:03:48 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 7F8A46B000D; Mon, 19 Aug 2019 05:03:48 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 70DCF6B000E; Mon, 19 Aug 2019 05:03:48 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0169.hostedemail.com [216.40.44.169]) by kanga.kvack.org (Postfix) with ESMTP id 51F0D6B0007 for ; Mon, 19 Aug 2019 05:03:48 -0400 (EDT) Received: from smtpin03.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with SMTP id 00839180AD805 for ; Mon, 19 Aug 2019 09:03:47 +0000 (UTC) X-FDA: 75838589736.03.spot15_3e311e15a3b23 X-HE-Tag: spot15_3e311e15a3b23 X-Filterd-Recvd-Size: 2489 Received: from mx1.redhat.com (mx1.redhat.com [209.132.183.28]) by imf08.hostedemail.com (Postfix) with ESMTP for ; Mon, 19 Aug 2019 09:03:47 +0000 (UTC) Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 193E6307D95F; Mon, 19 Aug 2019 09:03:46 +0000 (UTC) Received: from warthog.procyon.org.uk (ovpn-120-255.rdu2.redhat.com [10.10.120.255]) by smtp.corp.redhat.com (Postfix) with ESMTP id 190ED82489; Mon, 19 Aug 2019 09:03:44 +0000 (UTC) Organization: Red Hat UK Ltd. Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 3798903 From: David Howells In-Reply-To: <2b20bc62-d09c-d340-4f13-e20a850f4d47@suse.cz> References: <2b20bc62-d09c-d340-4f13-e20a850f4d47@suse.cz> <26518.1565273511@warthog.procyon.org.uk> To: Vlastimil Babka Cc: dhowells@redhat.com, Christoph Lameter , linux-mm@kvack.org Subject: Re: [PATCH] Add a slab corruption tracepoint MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-ID: <8355.1566205424.1@warthog.procyon.org.uk> Date: Mon, 19 Aug 2019 10:03:44 +0100 Message-ID: <8356.1566205424@warthog.procyon.org.uk> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.48]); Mon, 19 Aug 2019 09:03:46 +0000 (UTC) X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Vlastimil Babka wrote: > Shouldn't that include SLUB? I've been using SLAB. Looking in SLUB it's much less obvious where to insert the tracepoint. check_bytes_and_report() maybe? > I'm surprised to see SLAB used for debugging refcounting these days, The refcount debugging in question is not in SLAB, but rather in rxrpc; it's just SLAB detected the resulting memory corruption. rxrpc has tracepoints that track the refcounting, but SLAB printks a message to indicate the corruption and it's a bit tricky to work out where the printk happened with respect to the trace. > as the SLUB debugging features are vastly superior, while SLAB ones are > being sometimes found to be broken for years and removed. If SLUB is better than SLAB, shouldn't SLAB be removed? David