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]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id E4BAECD98D4 for ; Thu, 11 Jun 2026 07:56:30 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 375D76B0005; Thu, 11 Jun 2026 03:56:30 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 328BE6B0088; Thu, 11 Jun 2026 03:56:30 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 2157F6B008C; Thu, 11 Jun 2026 03:56:30 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0010.hostedemail.com [216.40.44.10]) by kanga.kvack.org (Postfix) with ESMTP id 0BD4A6B0005 for ; Thu, 11 Jun 2026 03:56:30 -0400 (EDT) Received: from smtpin26.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay10.hostedemail.com (Postfix) with ESMTP id 9DD7BC1E20 for ; Thu, 11 Jun 2026 07:56:29 +0000 (UTC) X-FDA: 84866874498.26.1C8F53B Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by imf06.hostedemail.com (Postfix) with ESMTP id 055B3180006 for ; Thu, 11 Jun 2026 07:56:27 +0000 (UTC) Authentication-Results: imf06.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=TwEgXzhc; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf06.hostedemail.com: domain of osalvador@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=osalvador@kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1781164588; 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=a4CUTTj1LLBvt23WQfDYUZoOfs2On1CLjSZO6t6REcI=; b=NSP4uYB/1hVN7q5wIhxD7uNjm9P7MiDiRmv7JRsj8YbxmdXn1VSb3gC1a+oQ/pQ27DB24L YYWZPzMUjBzlchW1BlO3/OAuY5d+m0pCvmFzdx1gxIQIf9YTgB11wwEV+d7Cb9QPoU2iYV HUSQSC954qWoUaTY7x004PeNZVK6/M4= ARC-Authentication-Results: i=1; imf06.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=TwEgXzhc; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf06.hostedemail.com: domain of osalvador@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=osalvador@kernel.org ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1781164588; b=bEIOTkWHepbmReTl6Qxj1HT0L4mbGhH7GLJIZ0m5BajhDFqxEV4F/+WYjSUJS9LBbC9+wb QivSBitKWrpuoNOgygeCPDNRlCB+QbIoifKa09Uh0FVlW4X5ouqraB8G+oE+PoJSCO6Nfz RFp3FiDcf0OBb9P0LiQCSokneptrG3I= Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by tor.source.kernel.org (Postfix) with ESMTP id 7A987600AA; Thu, 11 Jun 2026 07:56:27 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id A17F21F00893; Thu, 11 Jun 2026 07:56:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1781164587; bh=a4CUTTj1LLBvt23WQfDYUZoOfs2On1CLjSZO6t6REcI=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=TwEgXzhcjfcH+o8flQYenxnUgab6Oke/RjBQ1UCEhJcTQzCdm/PVDqD6orTJmZZDd WbhwEdep3rYaoG1RwJ5Os+ni6Kj+cVXdlhaKC8tcvpKzcjW4+oDmmSBO+WKArFPM8/ ZnkZEuRIq7Jv5v9eGCiLkK7rwEYwPM4eAGP3NW71PJeS2fMAllIo1UhxzqlBWhF5Sj qrtIBCl26qjNG+BFmZIKhYRUoXhsmA1RruEjlNESbrnREzi5UvjZisqIvJfGEzYTvM nODevr95peYmmpE7aOldoG+wRiuTpjwk9Im18sJVDO+8ZNnRVYe+iYeELHj5JKTuzL HWeug/S3df66g== Date: Thu, 11 Jun 2026 09:56:20 +0200 From: "Oscar Salvador (SUSE)" To: Lorenzo Stoakes Cc: Andrew Morton , Arnd Bergmann , Greg Kroah-Hartman , David Hildenbrand , "Liam R . Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Jann Horn , Pedro Falcato , linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH v3 1/3] drivers/char/mem: eliminate unnecessary use of success_hook Message-ID: References: <010579cca6787cf7bb057ab1f7228978b10601c8.1780397980.git.ljs@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <010579cca6787cf7bb057ab1f7228978b10601c8.1780397980.git.ljs@kernel.org> X-Rspamd-Server: rspam07 X-Rspam-User: X-Stat-Signature: 8kjdtqkffegsfjxdm1b8zni8xb5rs6e7 X-Rspamd-Queue-Id: 055B3180006 X-HE-Tag: 1781164587-959828 X-HE-Meta: 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 fUF9aUjR xTQMr0CGpJLRabUb+kBgPaL3banPBYLApj93r2HDk3e/x1Ym779O6WLADA8pIOWKQyZkFdWzp6wpAt+CMmG6YYd9uq4huHaAGiPlqzSgyzbgr00G5Pl0MeiQDaVXBlQtox+YHFeBWZ34Dy7mRM1kHDg1zgmQ17Jojxvjw7i5gFeuzMmMDC+XjK+kepWArUBZolBsSNr9n/8q4gC3C7AZu3Zl5PtIPZbWa9tZnwWuAmrXz3hwnbkRQi7AF0AK2hfWz5FIu/Jr2M6mke/FmVKpafUPlNB37KYIUTUqf Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, Jun 02, 2026 at 12:06:25PM +0100, Lorenzo Stoakes wrote: > /dev/zero, uniquely, marks memory mapped there as anonymous. This is > currently achieved using the mmap_action->success_hook. > > However this hook circumvents the abstraction of VMA initialisation so > it's preferable to do things a different way. > > To achieve this, this patch firstly defaults the VMA descriptor's vm_ops > field to the dummy VMA operations, which is what file-backed VMAs default > this field to. > > That way, we can detect whether a driver sets this field to NULL in order > to mark it anonymous. > > We then introduce vma_desc_set_anonymous() to do this explicitly, and > invoke it in mmap_zero_prepare(). > > This way, any driver which does not explicitly set desc->vm_ops, retains > the dummy vm_ops as they would previously. > > We also update set_vma_user_defined_fields() to make clear that we are > either setting vma->vm_ops to what is provided by the driver (or > defaulting to dummy_vm_ops if not set), or setting the VMA anonymous. > > This lays the groundwork for removing the success hook. > > Signed-off-by: Lorenzo Stoakes > Acked-by: David Hildenbrand (Arm) Reviewed-by: Oscar Salvador (SUSE) -- Oscar Salvador SUSE Labs