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 1F7F127291F; Tue, 11 Feb 2025 23:39:43 +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=1739317184; cv=none; b=nIACAXEAMG4tKLEDdc+Lo4KdDNxgKUP73i+PjET/PGXfO4gQMZXLkOyCefvYWMtl3j6IdHjFlfu0OxlTL5Bx90EgZC3hiLGEVus/nl6N0RaDzR4V0CXBbnmxQ15w736mMdIe3fH6OzspXSXJh8D7bmUwUa9qh6oLA6yfPs39Shk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1739317184; c=relaxed/simple; bh=KmZZdjl6ZufzH7ljJKE+F1Ax+O9hFfz9th1qlIB6io0=; h=Date:From:To:Cc:Subject:Message-Id:In-Reply-To:References: Mime-Version:Content-Type; b=K+Byi9cEOdL1b2RtMQTIjXXQa5i3ElCsokAkWICaklPU/pLkSP1zjD91dDHqYSiNurPHdFrsLs1KqwrKCp+WQnPchvcajh+3CSRFEMJ2kZsserv6r34tVcXo3JOXQt0yVl2Ltll2E8BgztCOmc0A2otIqGOJ9XmnAMHNFmLXa+4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=MqZw8H+Y; 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="MqZw8H+Y" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 734CEC4CEDD; Tue, 11 Feb 2025 23:39:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1739317183; bh=KmZZdjl6ZufzH7ljJKE+F1Ax+O9hFfz9th1qlIB6io0=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=MqZw8H+YK+HmXZ8Q98zirAJfh43qwJBjqC4G10PCMijbs7MHLqHyy8ij2y9JrFp4Y PCHqizlhN6EpikrsQQe5FdsUTHhsOTGGW834POt56J95wj2IetWFq/La6qE5s7qIWD lFtPuvJXA/j/mOsGzP0dkecwjTfjg+XXZoj2ZEHjV83V1j8ROlQO7rRak/uiOvJA7+ GC46whdgpIU6Xvnq5Jmy7ioG0f1iei8TH/XPQR2gdUyKJoF+trlW/z4vs9bTYwZCWE T73a/s3i3elPvGLGZuYHDZfYAQU6mW966xT7NDg9TdS7wXkHBwEM2UGTspNCS6kcLL pMQbYYW9qSPGg== Date: Wed, 12 Feb 2025 08:39:40 +0900 From: Masami Hiramatsu (Google) To: Steven Rostedt Cc: linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, Mark Rutland , Mathieu Desnoyers , Andrew Morton Subject: Re: [PATCH v3 1/2] mm/memblock: Add reserved memory release function Message-Id: <20250212083940.8a88be7b1f9cf68a2cb8465b@kernel.org> In-Reply-To: <20250211125211.1ce892a5@gandalf.local.home> References: <173928521419.906035.17750338150436695675.stgit@devnote2> <173928522350.906035.5626965043208329135.stgit@devnote2> <20250211125211.1ce892a5@gandalf.local.home> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Precedence: bulk X-Mailing-List: linux-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 12:52:11 -0500 Steven Rostedt wrote: > On Tue, 11 Feb 2025 23:47:03 +0900 > "Masami Hiramatsu (Google)" wrote: > > > 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) > > Cc: Andrew Morton > > Cc: Mike Rapoport > > Cc: linux-mm@kvack.org > > Hi, can we get one of the Memory Management maintainers to ack this patch? > > We will be having devices going out with the reserve_mem option to perform > tracing in the field. But that only happens if the user grants permission > to do so. But the kernel command line does not change between users that > granted permission and those that do not. We would like to free up the > memory for those devices where the users did not grant permission to trace, > as then the memory is just wasted. Thanks Steve for explaining, I missed Ccing the background information. Here is the covermail of this series. https://lore.kernel.org/all/173928521419.906035.17750338150436695675.stgit@devnote2/ Thank you, > > Thanks! > > -- Steve > > > > --- > > Changes in v2: > > - Rename reserved_mem_* to reserve_mem_*. > > --- > > 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..fe5f7711df04 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 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 095c18b5c430..c8d207ebb93c 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(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)(&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) > > +{ > > + struct reserve_mem_table *map; > > + unsigned int page_count; > > + phys_addr_t start; > > + > > + guard(mutex)(&reserve_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 > > */ > -- Masami Hiramatsu (Google)