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 3BB0BC282DE for ; Thu, 13 Mar 2025 08:44:42 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 2FD90280002; Thu, 13 Mar 2025 04:44:40 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 2AEAE280001; Thu, 13 Mar 2025 04:44:40 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 175EA280002; Thu, 13 Mar 2025 04:44:40 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id EE675280001 for ; Thu, 13 Mar 2025 04:44:39 -0400 (EDT) Received: from smtpin19.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay07.hostedemail.com (Postfix) with ESMTP id E4B5F161BEC for ; Thu, 13 Mar 2025 08:44:40 +0000 (UTC) X-FDA: 83215891920.19.D7E0A34 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) by imf04.hostedemail.com (Postfix) with ESMTP id C92AC40002 for ; Thu, 13 Mar 2025 08:44:38 +0000 (UTC) Authentication-Results: imf04.hostedemail.com; dkim=pass header.d=infradead.org header.s=bombadil.20210309 header.b=O9ugxHfA; dmarc=none; spf=none (imf04.hostedemail.com: domain of BATV+f9b963a332ab099747ce+7872+infradead.org+hch@bombadil.srs.infradead.org has no SPF policy when checking 198.137.202.133) smtp.mailfrom=BATV+f9b963a332ab099747ce+7872+infradead.org+hch@bombadil.srs.infradead.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1741855479; 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=J93E6Vw3VK+dqosx/C38S2yEZoCxKiYDJPynkA042n4=; b=F5ZaoOQjMLJ5aqEd2uEYIvYpz3cgzXx0sBVjSK4LiY2/mRu6e/Jp7txV1kklKV9ceI5JjB m9UK8j0N7pVtCF731HVn7QKbGQ+kCLVQnwV/9ijE4tBuzeBP0Pi6BNc1jKosZY4pSwkjw2 R+LIUmUcNpqq5FaonzrLlyWQMHZkI0A= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1741855479; a=rsa-sha256; cv=none; b=ooJQhXoTQWd7Fo1JzoKxwbF1I7YApCoPOWK4+P4Go3p4Wx8iqznAOFC/qP/l3SXMI8J44v N01bjVMF/tndBUKai+2oqfBNRYpuNWm22fxxAfwx25dXDi/MYwDnIVQrRyegMa4EoJ1Vr/ WJzx+Htup3wUR9MW/p1Jwx0ojGS+IAQ= ARC-Authentication-Results: i=1; imf04.hostedemail.com; dkim=pass header.d=infradead.org header.s=bombadil.20210309 header.b=O9ugxHfA; dmarc=none; spf=none (imf04.hostedemail.com: domain of BATV+f9b963a332ab099747ce+7872+infradead.org+hch@bombadil.srs.infradead.org has no SPF policy when checking 198.137.202.133) smtp.mailfrom=BATV+f9b963a332ab099747ce+7872+infradead.org+hch@bombadil.srs.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20210309; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=J93E6Vw3VK+dqosx/C38S2yEZoCxKiYDJPynkA042n4=; b=O9ugxHfAgY3WEudjUwN0Ar0xeU TbQNuDG9GefuP6cngv+wsY6/MzAfDSdqFiTuFFHLWP+l7kE9W2/W556UQe82tzHSzdY1jSk/Z0tuT W4h048ZXziXn9X3yWtR28bPmcZ5/O1+ZVTZM1BQLbgfCgBnyXvDp+S4xreX5JVpY1/mE5L/AA7Qsx nPMk4TlVD6/3Yo+5/ZyRPj1ZATrLoaqAGFQHtKqzeoNlatq5xVsjj6jOCdLGV9hCGu8phkz5p2e+D xqYlKFgxMEWuwZjK5sEMIWNwbA3CZYdvkFHWejT5KWGmM3wDf6FxCKjGUdGcAMJg3LkpHxvGIDJYJ yCZf1EQQ==; Received: from hch by bombadil.infradead.org with local (Exim 4.98 #2 (Red Hat Linux)) id 1tseB9-0000000AabG-2B0j; Thu, 13 Mar 2025 08:44:35 +0000 Date: Thu, 13 Mar 2025 01:44:35 -0700 From: Christoph Hellwig To: Hannes Reinecke Cc: Christoph Hellwig , Matthew Wilcox , Jakub Kicinski , Andrew Morton , netdev@vger.kernel.org, Vlastimil Babka , linux-mm@kvack.org Subject: Re: [PATCH] mm: Decline to manipulate the refcount on a slab page Message-ID: References: <20250310143544.1216127-1-willy@infradead.org> <20250311111511.2531b260@kernel.org> <4fc21641-e258-474b-9409-4949fe2fda2d@suse.de> <9af6dff3-adce-40f8-8649-282212acad9e@suse.de> <17f4795a-f6c8-4e6c-ba31-c65eab18efd1@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <17f4795a-f6c8-4e6c-ba31-c65eab18efd1@suse.de> X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: C92AC40002 X-Stat-Signature: q576q85q8g65musdz3gdbq58x5wgmw1j X-HE-Tag: 1741855478-500853 X-HE-Meta: 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 wVldVed/ +bEAjHoYsSf5yBTRpnHKMkmJ52atKzZ5gpcDisKUTGEZCGwmHMy4JqweQ7f2U//Jh4eFYXn7ylbA0erP6OLQf8SHrPVpEzHJY6DgeI+Pw7t3MzErrUsFeIqT/spt7ssyH0mXWE01IDkBBK5Jde6vEapeYmMPAv03zQQIMO+mTm7F4FlJ4Kk6TYrSZjzHUUINiSy0CFiQw8dKJkBQFb0cW6yHz+XeCYso825/Xp+GtbvF7V2xX5yxVIfCNib2O+ZjGiCZsGfeAbX/Bw0oueyPex59AW+6SR3e3kanKv/l7QWT2WsUSLksrth40rbVNEXHpcrRk0uGACsRW+C1m7AiFtrovAVzuC8uM4bc5dpQYzMEoYnwnL58Qt2LzxdEiSaWWh7Lp2c0cddhNheuVZ7HByRx+M9VPFk8kAVTWFo91koFm1xwl6ZYgpyuvOhWN74v3TiXFh1t1/GjoqT8Fk0MGcsNzJjBjp4Q8cXox 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 Thu, Mar 13, 2025 at 09:34:39AM +0100, Hannes Reinecke wrote: > nvmf_connect_command_prep() returns a kmalloced buffer. Yes. > That is stored in a bvec in _nvme_submit_sync_cmd() via > blk_mq_rq_map_kern()->bio_map_kern(). > And from that point on we are dealing with bvecs (iterators > and all), and losing the information that the page referenced > is a slab page. Yes. But so does every other consomer of the block layer that passes slab memory, of which there are quite a few. Various internal scsi and nvme command come to mind, as does the XFS buffer cache. > The argument is that the network layer expected a kvec iterator > when slab pages are referred to, not a bvec iterator. It doesn't. It just doesn't want you to use ->sendpage.