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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> MIME-Version: 1.0 X-Rspam-User: X-Rspamd-Queue-Id: ED0D0C0008 X-Stat-Signature: ohr948fh131u9j7zroj9ybzhcm6weodd X-Rspamd-Server: rspam03 X-HE-Tag: 1740615133-573323 X-HE-Meta: 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 EVi4VKuW 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 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.stgit@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 *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 */