From patchwork Tue Feb 18 15:08:58 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: 13980155 X-Patchwork-Delegate: rostedt@goodmis.org 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 464B0269AF4; Tue, 18 Feb 2025 15:09:02 +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=1739891343; cv=none; b=sBkORgSwAkhCIjSU+1JtYVN0807Mwki+88ktE3p2mTFe6SXgQo6ka+XYWJesYAsHkbt98ve7Fk2Q+DwBMtZlLqame2LU12AjFKC5KfAZOv8dggzqajznfQSQjA0mjXm8bYqzVLg29IwMh6h1e6ABauTIaHivGdWMQgHdMS2nF9c= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1739891343; c=relaxed/simple; bh=8v4zZwccKy+E3kLDMp/TBNu5P5+5ygdWnFUDTOV6vhs=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=sqM9m3MU0tBkKEMNGEdRbwUgLcbDoysN5y0yaI0ihX4j7TTFhe5wplrbjc8PkWuhnnXUpsbhK0RxaeFG5KHgO40+ocL91qjV9Ztj6tBbtieJjJ7I3Wl5uYOh4ucE0+3fODi9VCIhfyURYEjGbe7BNiSOrLB5XNI9BBZw9W4tYHg= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=e6dVhIcO; 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="e6dVhIcO" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D5ADCC4CEE7; Tue, 18 Feb 2025 15:09:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1739891342; bh=8v4zZwccKy+E3kLDMp/TBNu5P5+5ygdWnFUDTOV6vhs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=e6dVhIcOxjQStAmdg1frwiYYMzwqNWrkW5KnknEwHxn6tpy53X+QuZUBlpcLgZCf1 CKEhu0DH9fC/Je+UIYpHOPzeiwPitaHanVUV2TRGiHdKr/MFRFPslLVWDEouuekeZX 1PRKaxuasqXI3LWVdzF6hhzr8gJH93z6XH3BwEZEB0FX+PMovWkseGWpUlgTsaX1ZQ ce/usigvzflPg5s2CUSHiT/il3eC3bi6Xw3PXcd+ok8GBdoAez7t5tu9UCAdiAEX43 b1t6ue9XccNUA4FWE4IVLXzP5PnCWTOlfmlahs6HObelUFY4EQCD5F8DYhatYhD2Yu YOO2wMctHY73g== 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 , Mike Rapoport , linux-mm@kvack.org Subject: [PATCH v4 1/2] mm/memblock: Add reserved memory release function Date: Wed, 19 Feb 2025 00:08:58 +0900 Message-ID: <173989133862.230693.14094993331347437600.stgit@devnote2> X-Mailer: git-send-email 2.43.0 In-Reply-To: <173989132750.230693.15749600013776132201.stgit@devnote2> References: <173989132750.230693.15749600013776132201.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 reserve_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) Acked-by: Mike Rapoport (Microsoft) Cc: Andrew Morton Cc: linux-mm@kvack.org --- Changes in v4: - Use free_reserved_area() according to Mike's comment. Changes in v2: - Rename reserved_mem_* to reserve_mem_*. --- include/linux/mm.h | 1 + mm/memblock.c | 66 +++++++++++++++++++++++++++++++++++++++++++--------- 2 files changed, 55 insertions(+), 12 deletions(-) diff --git a/include/linux/mm.h b/include/linux/mm.h index 7b1068ddcbb7..1ee9e7447485 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -4123,6 +4123,7 @@ 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 reserve_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 95af35fd1389..8cd95f60015d 100644 --- a/mm/memblock.c +++ b/mm/memblock.c @@ -16,6 +16,7 @@ #include #include #include +#include #include #include @@ -2283,6 +2284,7 @@ struct reserve_mem_table { }; static struct reserve_mem_table reserved_mem_table[RESERVE_MEM_MAX_ENTRIES]; static int reserved_mem_count; +static DEFINE_MUTEX(reserve_mem_lock); /* Add wildcard region with a lookup name */ static void __init reserved_mem_add(phys_addr_t start, phys_addr_t size, @@ -2296,6 +2298,21 @@ 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 @@ -2309,22 +2326,47 @@ 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)(&reserve_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); +/** + * reserve_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 reserve_mem_release_by_name(const char *name) +{ + char buf[RESERVE_MEM_NAME_SIZE + 12]; + struct reserve_mem_table *map; + void *start, *end; + + guard(mutex)(&reserve_mem_lock); + map = reserve_mem_find_by_name_nolock(name); + if (!map) + return 0; + + start = phys_to_virt(map->start); + end = start + map->size - 1; + snprintf(buf, sizeof(buf), "reserve_mem:%s", name); + free_reserved_area(start, end, 0, buf); + map->size = 0; + + return 1; +} + /* * Parse reserve_mem=nn:align:name */