From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0C605383C8D; Wed, 2 Sep 2026 18:00:52 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788372053; cv=none; b=qMcwAdQDwAJlNjz7VYI10m+Oi58gnJDNdLmMfbLjPZ07enkAPzoyjddG0bUrpS85WYYDh6YPcHlZA3Dq/+9oBgVepwhe+sdbdW0BWur/z5oTRIjjWrhervo2NkDbkHGw484HugSyrA2IZv78+BbZccgWi0WiJPWqakV0b2g4iCQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788372053; c=relaxed/simple; bh=+lQ64M91uOCmTZQebnoxYSvQq7Jfy6kZG9l8lKXW1J4=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=fRSPKccaIMs5PesmvD2JKS0lOIjSws/x+GSuzKCzT8fA1S/Wip06uAFhqKa4nhW1ziJmYZfthogd/0Dhrh0hx9efueoLqvYz3Ak279nI5OO/RIIC3MHLLxItlj2vYz/NIc9DspRtdwjd9u4tKTKipOzPrZCT3Mshfvu6MEvYYO4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=OGydZTsC; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="OGydZTsC" 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 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: 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 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