From mboxrd@z Thu Jan 1 00:00:00 1970 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 5803520ED; Tue, 11 Feb 2025 00:03:03 +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=1739232184; cv=none; b=rnEHHq2KVIqET+wHZPJAZ2xLHiGN9/CGH4bfzICgt4c/9WKEC3s3CWA8w3ewClSVBxgV5+Q804KWWMi8lZHkljsx+EcjviAPIygYr87BuynzYHiPf5iWscqSFL7r5YG893LhDOoUZ1teCztiNexGNa2HweMHDRj3X1u+4ySez2I= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1739232184; c=relaxed/simple; bh=C2PkNuwJRg2pu3jrlhfoM3kK7xXOFeIRAETD3oKXU1o=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=HZRDZmKZYUVbn4ncvqVoHOpvfpFrBtkgGMxJA6Y/F6JeRbvDEf5fvFWWKMjz27fKUAnWtqphM22uto8U5lm+2maHJJtEXOmLOXCww6j/F1IAHZ4+DJNFMONgk8x9m9QQlI90JFC8m3MmqJWuCT30/scYXE0TJvFh+7sIbBH4PvI= 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 065C5C4CED1; Tue, 11 Feb 2025 00:03:02 +0000 (UTC) Date: Mon, 10 Feb 2025 19:03:06 -0500 From: Steven Rostedt To: "Masami Hiramatsu (Google)" Cc: linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, Mark Rutland , Mathieu Desnoyers , Andrew Morton , Mike Rapoport Subject: Re: [RFC PATCH v2 2/3] mm/memblock: Add reserved memory release function Message-ID: <20250210190306.6ffda2c7@gandalf.local.home> In-Reply-To: <173920224789.826592.13627374781649157364.stgit@devnote2> References: <173920222697.826592.3726270716809214055.stgit@devnote2> <173920224789.826592.13627374781649157364.stgit@devnote2> X-Mailer: Claws Mail 3.20.0git84 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Tue, 11 Feb 2025 00:44:08 +0900 "Masami Hiramatsu (Google)" wrote: > 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. Since Mike wrote the reserve_mem code, we should Cc him on changes. Also, I would make patches 2 and 3 a separate patchset, as it is unrelated to the other code. > > 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); Should be "reserve_mem_release_by_name()" and not "reserved_mem" to stay consistent. > > #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); "reserve_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 > */ Thanks, -- Steve