From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-io0-f198.google.com (mail-io0-f198.google.com [209.85.223.198]) by kanga.kvack.org (Postfix) with ESMTP id D456B440417 for ; Wed, 8 Nov 2017 10:05:14 -0500 (EST) Received: by mail-io0-f198.google.com with SMTP id i38so5767575iod.10 for ; Wed, 08 Nov 2017 07:05:14 -0800 (PST) Received: from resqmta-ch2-06v.sys.comcast.net (resqmta-ch2-06v.sys.comcast.net. [2001:558:fe21:29:69:252:207:38]) by mx.google.com with ESMTPS id 91si3743368ioq.86.2017.11.08.07.05.13 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 08 Nov 2017 07:05:13 -0800 (PST) Date: Wed, 8 Nov 2017 09:05:12 -0600 (CST) From: Christopher Lameter Subject: Re: [PATCH] slub: Fix sysfs duplicate filename creation when slub_debug=O In-Reply-To: <1510119138.17435.19.camel@mtkswgap22> Message-ID: References: <1510023934-17517-1-git-send-email-miles.chen@mediatek.com> <1510119138.17435.19.camel@mtkswgap22> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Sender: owner-linux-mm@kvack.org List-ID: To: Miles Chen Cc: Pekka Enberg , David Rientjes , Joonsoo Kim , Andrew Morton , linux-kernel@vger.kernel.org, linux-mm@kvack.org, wsd_upstream@mediatek.com, linux-mediatek@lists.infradead.org On Wed, 8 Nov 2017, Miles Chen wrote: > > Ok then the aliasing failed for some reason. The creation of the unique id > > and the alias detection needs to be in sync otherwise duplicate filenames > > are created. What is the difference there? > > The aliasing failed because find_mergeable() returns if (flags & > SLAB_NEVER_MERGE) is true. So we do not go to search for alias caches. > > __kmem_cache_alias() > find_mergeable() > kmem_cache_flags() --> setup flag by the slub_debug > if (flags & SLAB_NEVER_MERGE) return NULL; > ... > search alias logic... > > > The flags maybe changed if disable_higher_order_debug=1. So the > unmergeable cache becomes mergeable later. Ok so make sure taht the aliasing logic also clears those flags before checking for SLAB_NEVER_MERGE. > > The clearing of the DEBUG_METADATA_FLAGS looks ok to me. kmem_cache_alias > > should do the same right? > > > Yes, I think clearing DEBUG_METADATA flags in kmem_cache_alias is > another solution for this issue. > > We will need to do calculate_sizes() by using original flags and compare > the order of s->size and s->object_size when > disable_higher_order_debug=1. Hmmm... Or move the aliasing check to a point where we know the size of the slab objects? -- 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