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 6CC47C624D3 for ; Wed, 2 Sep 2026 18:00:56 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 416636B00AD; Wed, 2 Sep 2026 14:00:55 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 3A02D6B00B2; Wed, 2 Sep 2026 14:00:55 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 2DD9B6B00B3; Wed, 2 Sep 2026 14:00:55 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id 0D5E96B00AD for ; Wed, 2 Sep 2026 14:00:55 -0400 (EDT) Received: from smtpin04.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay01.hostedemail.com (Postfix) with ESMTP id 98F861C19EA for ; Wed, 2 Sep 2026 18:00:54 +0000 (UTC) X-FDA: 85169588028.04.8E7D76D Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by imf03.hostedemail.com (Postfix) with ESMTP id 9E5512000A for ; Wed, 2 Sep 2026 18:00:52 +0000 (UTC) Authentication-Results: imf03.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=OGydZTsC; spf=pass (imf03.hostedemail.com: domain of ljs@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=ljs@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1788372052; b=Rnw5O0HVNn52On8aV56lXWRe7ij3XUbJTi8JUOwvQktXecsqeiJ68t9JDP4srU2tvzrMg9 wwiLg/JTq16eHrFazQ6COyYGwSs/ddgB44wq1bAJuaiHmXNm8UwmHDgmeSO4zoBahbul2M CPvRJn70lKvJjL0OsaEmkEXSTlfAwRQ= ARC-Authentication-Results: i=1; imf03.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=OGydZTsC; spf=pass (imf03.hostedemail.com: domain of ljs@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=ljs@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1788372052; 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:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=FkujdrJ/pdcNwpIbp+sSj6hn+DXxw2Xn58xtJMFlJxs=; b=XgJ3w2WM4lgKzZ5vtMF+jnIiqR6xwlfxf7ZnejMJWMFANh+0E+j5vW58bn56CC4/6yjVnd E4OUT7Bf94lsO4ZgT/VEXDaeAywMG/MjsRpFec+cOwpaHUx64eh+714yj/tPcp35jwbCv3 QAloIGNt5zx8uBEa1VDruKhEk1Wtna0= Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by tor.source.kernel.org (Postfix) with ESMTP id 32C1A60230; Wed, 2 Sep 2026 18:00:52 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id D90601F00A3A; Wed, 2 Sep 2026 18:00:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788372051; bh=FkujdrJ/pdcNwpIbp+sSj6hn+DXxw2Xn58xtJMFlJxs=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=OGydZTsC4RGgesW31RFvGv8NgGNrrRKWaqywQDMxbqsW3Wyx/EAVj4VvJR4KJQbPD hym+9RctbEOEGHMpWGfFbBe3BnGzDbiq24XumBUsaPFDDJaTAoU8HQI+YJHXCFOK5g NgZh6lej/czw/qPob3S7F7vTewedg/mXKnNvl9bdyz8PJayZs4oGeHzKFSk4O92+FK Bvp3bCd6znxQJFZrEFrBVszkU5TEgG6yVESvbT0BrYMJCmt+ZQpPaVkwC+dQ6lRCpl d6OeS478mdWn1liNL+w1RxG1n2/Ml2n+QqX2Qu9+MSrvgcT3P8BLCMCJLKzxNCkmJV /kJ5V4j43Y/xA== From: "Lorenzo Stoakes (ARM)" Date: Wed, 02 Sep 2026 19:00:18 +0100 Subject: [PATCH 1/6] mm: move drivers/char/mem.c to mm/char-mem.c MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20260902-map-private-dev-zero-v1-1-a578c730cec7@kernel.org> References: <20260902-map-private-dev-zero-v1-0-a578c730cec7@kernel.org> In-Reply-To: <20260902-map-private-dev-zero-v1-0-a578c730cec7@kernel.org> To: Arnd Bergmann , Greg Kroah-Hartman , Andrew Morton , "Liam R. Howlett" , Vlastimil Babka , Jann Horn , Pedro Falcato , David Hildenbrand , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Hugh Dickins , Baolin Wang , "Matthew Wilcox (Oracle)" , Jan Kara Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-kselftest@vger.kernel.org, "Lorenzo Stoakes (ARM)" X-Mailer: b4 0.14.3 X-Developer-Signature: v=1; a=openpgp-sha256; l=3541; i=ljs@kernel.org; h=from:subject:message-id; bh=+lQ64M91uOCmTZQebnoxYSvQq7Jfy6kZG9l8lKXW1J4=; b=owGbwMvMwCV2fu7ZrsZH9SKMp9WSGLJmpHg9UN0a/7/TWUg8x1o8wJEhtUpBeIuz+fbSa8W7/ zObn2PqKGVhEONikBVTZHn+RXx/kEjYvM4L/m4wc1iZQIYwcHEKwES+nWVkOLx4/glBmX8CS0Ju N0R7HdjYZGh3L3mhVNVJ0x2/leXSuxkZvrf0GS0/11DnPH/nmmXZixev8t3nq/U/6vO9NzdmC07 7zQAA X-Developer-Key: i=ljs@kernel.org; a=openpgp; fpr=E7F417BF5214569E89D04F46CF9DCD8A81E27F14 X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 9E5512000A X-Stat-Signature: grfnf1a383mit6e5y397dqyk8fn157m1 X-Rspam-User: X-HE-Tag: 1788372052-112957 X-HE-Meta: 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 1sEgTnH9 SDmNVqMKWLpx4ZDDm/EAIR/pu0a7JdSI1Siurhp+biD6bR8rP1I22KNNR758jsd7QTZ9wDuZ0pZevMTYx6BOM23WopW6A9QrkrWgU8nw08YSZt3pO7KyV+QPPygz4Xd/g+Ub83UClBFl3pxv/q+5NZrf55EL1iwsA32F1Qv+xjOPnnazThOgb9bh595ZE1awsgnXU+LXwKxVpI6GyX94R3mVBji6F2ZMp0XeHbEUShc/r83DREQLupGFlGR/OomNLgnd9nfqDrn9c2LBRXvx3OQ/83KDoag28cSq4vCSZY2T+9N6wMnINoDr9wxasIgKCGBOiTqsa3sO9s6qXLaIBelSaXeJt6oANkbaDRpWaaD5xV0M= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: The memory character driver implements several mm-specific features and is always compiled into the kernel, so move it to mm/ where it belongs. Among other things the driver implements /dev/mem which provides raw access to physical memory, and /dev/zero which either allows mapping of a shmem region (if mapped with MAP_SHARED) or, uniquely, anonymous memory (if mapped MAP_PRIVATE). This change lays the foundations to allow MAP_PRIVATE-/dev/zero to be mapped precisely the same as anonymous memory is mapped as currently it is an edge case within mm. Also update a couple of comments that reference 'drivers/char/mem.c' to reference 'mm/char-mem.c'. Signed-off-by: Lorenzo Stoakes (ARM) --- MAINTAINERS | 4 ++-- drivers/char/Makefile | 2 +- mm/Makefile | 3 ++- drivers/char/mem.c => mm/char-mem.c | 2 +- mm/shmem.c | 2 +- 5 files changed, 7 insertions(+), 6 deletions(-) diff --git a/MAINTAINERS b/MAINTAINERS index 2133aec4a200..ebadf4cef076 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -17272,7 +17272,7 @@ F: Documentation/ABI/testing/sysfs-kernel-mm-memory-tiers F: Documentation/ABI/testing/sysfs-kernel-mm-numa F: Documentation/admin-guide/mm/ F: Documentation/mm/ -F: drivers/char/mem.c +F: mm/char-mem.c F: include/linux/cma.h F: include/linux/dmapool.h F: include/linux/ioremap.h @@ -17477,7 +17477,7 @@ L: linux-mm@kvack.org S: Maintained W: http://www.linux-mm.org T: git git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm -F: drivers/char/mem.c +F: mm/char-mem.c F: include/trace/events/mmap.h F: fs/proc/task_mmu.c F: fs/proc/task_nommu.c diff --git a/drivers/char/Makefile b/drivers/char/Makefile index a46d7bf7c4c8..bb3bf66937b3 100644 --- a/drivers/char/Makefile +++ b/drivers/char/Makefile @@ -3,7 +3,7 @@ # Makefile for the kernel character device drivers. # -obj-y += mem.o random.o +obj-y += random.o obj-$(CONFIG_TTY_PRINTK) += ttyprintk.o obj-y += misc.o obj-$(CONFIG_TEST_MISC_MINOR) += misc_minor_kunit.o diff --git a/mm/Makefile b/mm/Makefile index e7245cb88c66..2a3ec53d62ee 100644 --- a/mm/Makefile +++ b/mm/Makefile @@ -55,7 +55,8 @@ obj-y := filemap.o mempool.o oom_kill.o fadvise.o \ mm_init.o percpu.o slab_common.o \ compaction.o show_mem.o \ interval_tree.o list_lru.o workingset.o \ - debug.o gup.o mmap_lock.o vma_init.o $(mmu-y) + debug.o gup.o mmap_lock.o vma_init.o char-mem.o \ + $(mmu-y) # Give 'page_alloc' its own module-parameter namespace page-alloc-y := page_alloc.o diff --git a/drivers/char/mem.c b/mm/char-mem.c similarity index 99% rename from drivers/char/mem.c rename to mm/char-mem.c index 63253d1de5d7..d2e575545044 100644 --- a/drivers/char/mem.c +++ b/mm/char-mem.c @@ -1,6 +1,6 @@ // SPDX-License-Identifier: GPL-2.0 /* - * linux/drivers/char/mem.c + * mm/char-mem.c * * Copyright (C) 1991, 1992 Linus Torvalds * diff --git a/mm/shmem.c b/mm/shmem.c index 255d69ebceba..c92ed17dbc4a 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -2981,7 +2981,7 @@ unsigned long shmem_get_unmapped_area(struct file *file, sb = file_inode(file)->i_sb; } else { /* - * Called directly from mm/mmap.c, or drivers/char/mem.c + * Called directly from mm/mmap.c, or mm/char-mem.c * for "/dev/zero", to create a shared anonymous object. */ if (IS_ERR(shm_mnt)) -- 2.55.0