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 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2765AD44D57 for ; Wed, 6 Nov 2024 12:05:54 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id B57DF6B008A; Wed, 6 Nov 2024 07:05:53 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id B07DB6B009A; Wed, 6 Nov 2024 07:05:53 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 9A9316B00AE; Wed, 6 Nov 2024 07:05:53 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0013.hostedemail.com [216.40.44.13]) by kanga.kvack.org (Postfix) with ESMTP id 7D76C6B008A for ; Wed, 6 Nov 2024 07:05:53 -0500 (EST) Received: from smtpin24.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay08.hostedemail.com (Postfix) with ESMTP id 08E3D141C00 for ; Wed, 6 Nov 2024 12:05:52 +0000 (UTC) X-FDA: 82755540378.24.B4779D3 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by imf04.hostedemail.com (Postfix) with ESMTP id 7ADE240011 for ; Wed, 6 Nov 2024 12:05:07 +0000 (UTC) Authentication-Results: imf04.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=LuBpQvmQ; dmarc=pass (policy=none) header.from=redhat.com; spf=pass (imf04.hostedemail.com: domain of mpatocka@redhat.com designates 170.10.129.124 as permitted sender) smtp.mailfrom=mpatocka@redhat.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1730894627; a=rsa-sha256; cv=none; b=DL8mN5PuaooHvj5i1Q+71PvrIFq8qRg1NiFIpfo+1vi4QwbERLTsN6NtPMzmUZmfSBGNg0 jE5xIyzZnqBDbovne+pc3Pmik1PjNKNAHTCTO4nOW4S28oqOMrXtlVaV7cE962vjK15bpa cGjkdcx2hRgYdTgv+6VPVheSJtZVdsg= ARC-Authentication-Results: i=1; imf04.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=LuBpQvmQ; dmarc=pass (policy=none) header.from=redhat.com; spf=pass (imf04.hostedemail.com: domain of mpatocka@redhat.com designates 170.10.129.124 as permitted sender) smtp.mailfrom=mpatocka@redhat.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1730894627; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=JvulnFlXg1Y97GkXTZTrV/U45YP/j/xJhXGySebYtKQ=; b=FlEk+QwjeJq+aAaz/VJpMKDpkLjuhona2qFpA0Mm3gonwrE+E6Bqxb7QiipYJNTSTC4AaF sDppGUyIEpr01GP8MOo17Q7R0GxC9mMo6cTi9vIjBcugmGeknxBpFkIyYc7XbWoy6Rv1T2 z5YPpyGPINZMpodCQZViozqLrvpE7Kg= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1730894750; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=JvulnFlXg1Y97GkXTZTrV/U45YP/j/xJhXGySebYtKQ=; b=LuBpQvmQFLKhnHc710a4OezN5qQ2Eks+/lujF4Rc9vtAe/z8uKVcaZVEd8Xs0dW3EOJJR1 qKHzO2dceW2y8sBTPleWltODMyRP3lAYsVMni0UNjCGB875kVqQjnNEZs7Y3fC7R3bt6N2 /0tLFApxo6zCgh523Cu40+UbXP5HXm4= Received: from mx-prod-mc-01.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-611-w6jG2KNWPgu-aRIDFqgC5Q-1; Wed, 06 Nov 2024 07:05:47 -0500 X-MC-Unique: w6jG2KNWPgu-aRIDFqgC5Q-1 X-Mimecast-MFC-AGG-ID: w6jG2KNWPgu-aRIDFqgC5Q Received: from mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.17]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 88D4E19560B2; Wed, 6 Nov 2024 12:05:45 +0000 (UTC) Received: from [10.45.225.180] (unknown [10.45.225.180]) by mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 0215E1955F40; Wed, 6 Nov 2024 12:05:41 +0000 (UTC) Date: Wed, 6 Nov 2024 13:05:38 +0100 (CET) From: Mikulas Patocka To: Vlastimil Babka cc: Pedro Falcato , Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , Andrew Morton , zkabelac@redhat.com, Roman Gushchin , Hyeonggon Yoo <42.hyeyoo@gmail.com>, linux-mm@kvack.org Subject: Re: slab warning: kmem_cache of name 'dm_bufio_buffer' already exists In-Reply-To: <5a1e67c3-481e-4c6e-8507-5a8ea0bd9f28@suse.cz> Message-ID: <27ba7473-9255-2407-8e4e-e5c3cafc25c4@redhat.com> References: <9c3fecc3-19dc-42d4-6c89-4a48e9ad19cc@redhat.com> <5a1e67c3-481e-4c6e-8507-5a8ea0bd9f28@suse.cz> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.0 on 10.30.177.17 X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: dgrf2QPreYK_UkMMwKU8nunSwPOID6eatHbN7ifWq-o_1730894745 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=US-ASCII X-Rspamd-Queue-Id: 7ADE240011 X-Stat-Signature: gmcmfo7jixykxc3qj86ib64xjox8ci3i X-Rspam-User: X-Rspamd-Server: rspam05 X-HE-Tag: 1730894707-895067 X-HE-Meta: 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 AgJcMcSF MmXisQOVPZakObWO4r6NqTVWNSKdVkq2RGRMBR2bpF+7fvYF+ZPmahkiqUzSy4/eVT13aRudB49ibhJVM2FJElDbJYtSA8SrSlSiuHHaNxN7bKjSmvFXJyWLnas3a8rOQ/32sBiRmWi3KVVdz3PoKHlmKiyzDdaGNJp+5fq1tUhzWT9ZPPTYbfFpLltBoELwYVkj3VQDccL4aFL2rs0A5W4VFRe3YKzkFpEwZs12e5R3Oj9pVH5RJyq0gPk0pMYRIt3zHMnsbRJLemjv4nBxHTTJS3vTupTubyfhD25DusxDgQ/Ns8Hkb/EhugkZS9TUDhQ5rmZc7OgDX9PItd+grsf4NGvB9GTlvppmxke8QBA/4nHIBvBleQyRxlPRNucoeX7ffNHCSy266ylviTMcgNqxfbWymESPbChUYr7JcAoiq1ZHpianJ8btF9BBmY7pEBRF0feGB+kTHaGfpafKtnsuN8C960i+oqGlR 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: List-Subscribe: List-Unsubscribe: On Wed, 6 Nov 2024, Vlastimil Babka wrote: > On 11/6/24 12:19, Mikulas Patocka wrote: > > Hi > > Hi, > > > The commit 4c39529663b93165953ecf9b1a9ea817358dcd06 ("slab: Warn on > > duplicate cache names when DEBUG_VM=y") is causing large number of > > warnings about "dm_bufio_buffer", "dm_bufio_buffer-%u" (and other) device > > mapper caches. > > Hmm wonder why nobody run into this before. We thought the code that would > cause the warning would be all fixed before introducing it, but we missed > some, sorry. > > > I'd like to ask - how to properly fix it? > > > > We create a "dm_bufio_buffer" or "dm_bufio_buffer-%u" cache with every dm > > bufio client. It used to work (and the duplicate caches are merged), but > > Note the merging can be disabled so then it's really several caches with > exactly same name in /proc/slabinfo and inability to create their > sysfs/debugfs directories. Would it be sensible to allow merging caches with the same name and same attributes and only warn if there are caches with the same name and different attributes? > > now it warns. > > > > Should I append a pointer to the dm_bufio structure to the slab cache name > > to make them different? Or is there any other preferred solution? > > Anything that uniquely identifies the client should be ok, but beware e.g. > device names that can have slashes, see commit a360f311f57a36 (also for the > simplest possible fix that is an incremented number). > > > Note that it is not possible to pre-create the cache "dm_bufio_buffer-%u" > > in the module's init function, because the size of per-buffer auxiliary > > data is not known at this point. > > Looks like some chose to solve this the harder way, see 4d784c042d164f This seems too complicated. The always increasing sequence number seems like a better soltion. Mikulas