From nobody Tue Feb 10 19:01:03 2026 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 11A41BE4F for ; Thu, 27 Feb 2025 00:12:12 +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=1740615133; cv=none; b=tkmrQFW+rbrxOvLq+xwxeLTF/6vgpqQzk1VqiABSHZHOCQ+VYaog6iEH+TZWDDvMASvvSopcYqMaMI9hJFAj7hHSiJpOMVq5X0EWnEyGa+Dsz9UfQ+nypRM1qmhSWen9WXcUc0mUkUDfbYb3Vm2c8Tgs645EOjeZLctMM5ZM0Ts= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1740615133; c=relaxed/simple; bh=ZLwh4kTeifDTY9uIjXp+TmPGZdPu1espl9jSu0PMnds=; h=Message-ID:Date:From:To:Cc:Subject:References:MIME-Version: Content-Type; b=ZWtdbxQWsPpyGDu1DdFMPb8yy+iEP6lC4hb4vZX7LyizBGxm3m0fZSpGVIZbdzNhY1v6EDeN8kQ7AitnMMOca3Gw5IwgLBRvJLDrrDAe6G5TJy9EKC+lCpVV06XuayzkYaru/x7GfZnlu/vkIGu4Ns8ARmdzt/TR+DtOJCaWfHo= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 Received: by smtp.kernel.org (Postfix) with ESMTPSA id AF7B3C4CEEB; Thu, 27 Feb 2025 00:12:12 +0000 (UTC) Received: from rostedt by gandalf with local (Exim 4.98) (envelope-from ) id 1tnRWI-00000009XR3-2Wns; Wed, 26 Feb 2025 19:12:54 -0500 Message-ID: <20250227001254.455561171@goodmis.org> User-Agent: quilt/0.68 Date: Wed, 26 Feb 2025 19:12:37 -0500 From: Steven Rostedt To: linux-kernel@vger.kernel.org Cc: Masami Hiramatsu , Mark Rutland , Mathieu Desnoyers , Andrew Morton , "Mike Rapoport (Microsoft)" , linux-mm@kvack.org Subject: [for-next][PATCH 2/3] mm/memblock: Add reserved memory release function References: <20250227001235.355892523@goodmis.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" 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: Mark Rutland Cc: Mathieu Desnoyers Cc: linux-mm@kvack.org Link: https://lore.kernel.org/173989133862.230693.14094993331347437600.stgi= t@devnote2 Signed-off-by: Steven Rostedt (Google) --- 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 *vm= a); void vma_pgtable_walk_end(struct vm_area_struct *vma); =20 int reserve_mem_find_by_name(const char *name, phys_addr_t *start, phys_ad= dr_t *size); +int reserve_mem_release_by_name(const char *name); =20 #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 =20 #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); =20 /* 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 star= t, phys_addr_t size, strscpy(map->name, name); } =20 +static struct reserve_mem_table *reserve_mem_find_by_name_nolock(const cha= r *name) +{ + struct reserve_mem_table *map; + int i; + + for (i =3D 0; i < reserved_mem_count; i++) { + map =3D &reserved_mem_table[i]; + if (!map->size) + continue; + if (strcmp(name, map->name) =3D=3D 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 sta= rt, phys_addr_t size, int reserve_mem_find_by_name(const char *name, phys_addr_t *start, phys_ad= dr_t *size) { struct reserve_mem_table *map; - int i; =20 - for (i =3D 0; i < reserved_mem_count; i++) { - map =3D &reserved_mem_table[i]; - if (!map->size) - continue; - if (strcmp(name, map->name) =3D=3D 0) { - *start =3D map->start; - *size =3D map->size; - return 1; - } - } - return 0; + guard(mutex)(&reserve_mem_lock); + map =3D reserve_mem_find_by_name_nolock(name); + if (!map) + return 0; + + *start =3D map->start; + *size =3D map->size; + return 1; } EXPORT_SYMBOL_GPL(reserve_mem_find_by_name); =20 +/** + * reserve_mem_release_by_name - Release reserved memory region with a giv= en 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 bec= omes 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 =3D reserve_mem_find_by_name_nolock(name); + if (!map) + return 0; + + start =3D phys_to_virt(map->start); + end =3D start + map->size - 1; + snprintf(buf, sizeof(buf), "reserve_mem:%s", name); + free_reserved_area(start, end, 0, buf); + map->size =3D 0; + + return 1; +} + /* * Parse reserve_mem=3Dnn:align:name */ --=20 2.47.2