From patchwork Mon Feb 10 15:44:08 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Masami Hiramatsu (Google)" X-Patchwork-Id: 13968091 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 7510624BD0E; Mon, 10 Feb 2025 15:44:12 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1739202252; cv=none; b=d4j+ZYl7qjCiTWOzFjjMZZym5OnPsihHeua4d2UzR30DVwQT3aZlDZ8wqKpCAUSwmB9zWoWmmCmkRg3wRv0P8imNKGNLZC/F/dJwzLXNTYKQhPdG9oZnL409RSLqyB5V5UsHv/yYq7IkOo13G3VrqOfYIewpT6IOi59FGrYahpM= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1739202252; c=relaxed/simple; bh=6yj73383fNCr7f3+rQlSRto99A/AVeQ+lfiwks1wc1E=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=SoBctGV0lfjXfK8u+QZUs8bM+zQ6cuevCOsE0X5TlpLcC2q8db6sOIabJvSkaXmvGef//9dcIxuYYMGkod42QC5/eM7zRR3YXBuCYmKbN6EFDkZCyT0pRn+2KZzIG4JxXY8Eauqwo6OEHQ5ydEA5guDW+7uRLFnnfeKIlnvF0y0= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=tVQjzbui; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="tVQjzbui" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7355FC4CEDF; Mon, 10 Feb 2025 15:44:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1739202252; bh=6yj73383fNCr7f3+rQlSRto99A/AVeQ+lfiwks1wc1E=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=tVQjzbuiVX3bd/a9qyUKCfAl7FY/FkNbIseS22+tBhIl1/aEywAP5m85vcM+8HAzT 4DXgBPuBrTItQWgQRC4sS6jPECS7JsR3y4C41OckduwvlKztIDYjkhYZyRXcPkP2bE Pb5RsaKx2hkB2bSlX6ilS2BfD9aGOhWoIMct3btFgHdpw+0VZW70zQBmIucP7rvGA0 eXG+oRkcrlSfc8uwB/qvtboRB/XEB8bJASqeyT0kiOQyWHD9hgg1paTvUViUf5RNXM 85cKP28li5M+4VW3rjU4qnj0MtPl5/nRaBzoIInZ2dihqJNwgjrwRDLwqf9tDPuUsr 3n9DG/oqGmy6g== From: "Masami Hiramatsu (Google)" To: Steven Rostedt Cc: Masami Hiramatsu , linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, Mark Rutland , Mathieu Desnoyers , Andrew Morton Subject: [RFC PATCH v2 2/3] mm/memblock: Add reserved memory release function Date: Tue, 11 Feb 2025 00:44:08 +0900 Message-ID: <173920224789.826592.13627374781649157364.stgit@devnote2> X-Mailer: git-send-email 2.43.0 In-Reply-To: <173920222697.826592.3726270716809214055.stgit@devnote2> References: <173920222697.826592.3726270716809214055.stgit@devnote2> User-Agent: StGit/0.19 Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 From: Masami Hiramatsu (Google) Add reserved_mem_release_by_name() to release a reserved memory region with a given name. This allows us to release reserved memory which is defined by kernel cmdline, after boot. Signed-off-by: Masami Hiramatsu (Google) --- include/linux/mm.h | 1 + mm/memblock.c | 72 +++++++++++++++++++++++++++++++++++++++++++--------- 2 files changed, 61 insertions(+), 12 deletions(-) diff --git a/include/linux/mm.h b/include/linux/mm.h index f02925447e59..a7201824c1fc 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -4197,6 +4197,7 @@ void vma_pgtable_walk_begin(struct vm_area_struct *vma); void vma_pgtable_walk_end(struct vm_area_struct *vma); int reserve_mem_find_by_name(const char *name, phys_addr_t *start, phys_addr_t *size); +int reserved_mem_release_by_name(const char *name); #ifdef CONFIG_64BIT int do_mseal(unsigned long start, size_t len_in, unsigned long flags); diff --git a/mm/memblock.c b/mm/memblock.c index 095c18b5c430..9962fbb90597 100644 --- a/mm/memblock.c +++ b/mm/memblock.c @@ -16,6 +16,7 @@ #include #include #include +#include #include #include @@ -2263,6 +2264,7 @@ struct reserve_mem_table { }; static struct reserve_mem_table reserved_mem_table[RESERVE_MEM_MAX_ENTRIES]; static int reserved_mem_count; +static DEFINE_MUTEX(reserved_mem_lock); /* Add wildcard region with a lookup name */ static void __init reserved_mem_add(phys_addr_t start, phys_addr_t size, @@ -2276,6 +2278,21 @@ static void __init reserved_mem_add(phys_addr_t start, phys_addr_t size, strscpy(map->name, name); } +static struct reserve_mem_table *reserve_mem_find_by_name_nolock(const char *name) +{ + struct reserve_mem_table *map; + int i; + + for (i = 0; i < reserved_mem_count; i++) { + map = &reserved_mem_table[i]; + if (!map->size) + continue; + if (strcmp(name, map->name) == 0) + return map; + } + return NULL; +} + /** * reserve_mem_find_by_name - Find reserved memory region with a given name * @name: The name that is attached to a reserved memory region @@ -2289,22 +2306,53 @@ static void __init reserved_mem_add(phys_addr_t start, phys_addr_t size, int reserve_mem_find_by_name(const char *name, phys_addr_t *start, phys_addr_t *size) { struct reserve_mem_table *map; - int i; - for (i = 0; i < reserved_mem_count; i++) { - map = &reserved_mem_table[i]; - if (!map->size) - continue; - if (strcmp(name, map->name) == 0) { - *start = map->start; - *size = map->size; - return 1; - } - } - return 0; + guard(mutex)(&reserved_mem_lock); + map = reserve_mem_find_by_name_nolock(name); + if (!map) + return 0; + + *start = map->start; + *size = map->size; + return 1; } EXPORT_SYMBOL_GPL(reserve_mem_find_by_name); +/** + * reserved_mem_release_by_name - Release reserved memory region with a given name + * @name: The name that is attatched to a reserved memory region + * + * Forcibly release the pages in the reserved memory region so that those memory + * can be used as free memory. After released the reserved region size becomes 0. + * + * Returns: 1 if released or 0 if not found. + */ +int reserved_mem_release_by_name(const char *name) +{ + struct reserve_mem_table *map; + unsigned int page_count; + phys_addr_t start; + + guard(mutex)(&reserved_mem_lock); + map = reserve_mem_find_by_name_nolock(name); + if (!map) + return 0; + + start = map->start; + page_count = DIV_ROUND_UP(map->size, PAGE_SIZE); + + for (int i = 0; i < page_count; i++) { + phys_addr_t addr = start + i * PAGE_SIZE; + struct page *page = pfn_to_page(addr >> PAGE_SHIFT); + + page->flags &= ~BIT(PG_reserved); + __free_page(page); + } + map->size = 0; + + return 1; +} + /* * Parse reserve_mem=nn:align:name */