From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 9F5B3486647; Thu, 10 Sep 2026 14:33:07 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789050789; cv=none; b=PcCden9D8ieBRCBlcn6/GYF+mp5RUkKNmBSm8tKndZaK3h4GS6j7fp3q4sxobDB55AtJGv/Bh79n/slFTUMP5W6A2pT1aQY1zJNk7ESyO8JC6J/DHmv+bWjDTpbD8Q52HJqzfbIIY2fHjtvolRaxH08fKhqyObnJoDKJ6WFFISg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789050789; c=relaxed/simple; bh=1yKBBJoEhXzT0u7RXKa99EZc/h48jj478Y+U/NvKOpM=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=R97l3yN6sn0u2sKqyx+SxcsvWDVUJhoUESXA+x/mH3ZXB73e18G3LaWVy6h+GYJB9A2b21nkPZ8quasGFTmvrduME/6jPr9DUVwMk55xnibQKmeWfG+af5+p3/RTh9gpczQdI7f55b3bJ/xqvL+j78nCvmkjm2f8wENLMVRbP6o= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=GEBarzsa; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="GEBarzsa" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5656C1F000FF; Thu, 10 Sep 2026 14:32:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1789050787; bh=mzNbcMB0p1eY0jFGMUsfswHJRjfiaKQRPsj4bDo0LJw=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=GEBarzsaT/GfzNrEw1IDRcdc2Qi0z6RKPkaAX+irMV1fAySbMqtNp/r7WYAtWlxfa l3imiHeM/NxsuPRGU8OkkBuYY1c5w+2J0g4wjwX2QsglvTKjc+S3jJvaZd7CQv8++S 3E5z/N6S904KA/e+KOP67vV4XKI/FSODkKMiVx4S5PYKHysvIm6DbONe6+TXkarxZz LTaMtBZ79JK5EJJ4BnVoV3Y1SwXRjtvoyhTrLg3sImW9ITHVpwqjLjHTOj+QuweXrH lgOauZIYiV5A4zwAtlEZEa61OpwegJ6FPItysFxgJXrzzLRYiYqGkSYj/sMlNflbt1 Ni9OnEb92Lu1w== Date: Thu, 10 Sep 2026 15:32:56 +0100 From: "Lorenzo Stoakes (ARM)" To: "David Hildenbrand (Arm)" Cc: Andrew Morton , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Kairui Song , Qi Zheng , Shakeel Butt , Barry Song , Axel Rasmussen , Yuanchu Xie , Wei Xu , Baoquan He , Baolin Wang , Brendan Jackman , Johannes Weiner , Zi Yan , Oscar Salvador , Greg Kroah-Hartman , "Rafael J. Wysocki" , Danilo Krummrich , Jan Kiszka , Kieran Bingham , linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-cxl@vger.kernel.org, driver-core@lists.linux.dev, linux-fsdevel@vger.kernel.org Subject: Re: [PATCH 09/12] mm/sparse: remove SECTION_MARKED_PRESENT Message-ID: References: <20260909-b4-sparsemem_cleanups-v1-0-008fc8d579fe@kernel.org> <20260909-b4-sparsemem_cleanups-v1-9-008fc8d579fe@kernel.org> 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-Disposition: inline In-Reply-To: <20260909-b4-sparsemem_cleanups-v1-9-008fc8d579fe@kernel.org> On Wed, Sep 09, 2026 at 03:33:02PM +0200, David Hildenbrand (Arm) wrote: > All present section iterators run before memory hotplug added any > further memory sections, Therefore, we can simply use the SECTION_IS_EARLY > flag by setting that flag earlier in sparse_prepare_early_sections(). Hmm? sparse_prepare_early_sections() doesn't seem to be a function that exists? Do you mean sparse_sections_init()? > > Get rid of SECTION_MARKED_PRESENT entirely and rename > for_each_present_section_nr() to for_each_early_section_nr(). > > Also update the gdb script to use the updated value for > SECTION_IS_EARLY. The change seems fine. > > No functional change intended. > > Signed-off-by: David Hildenbrand (Arm) With commit msg updated: Acked-by: Lorenzo Stoakes (ARM) One small question type comment below. > --- > drivers/base/memory.c | 2 +- > include/linux/mmzone.h | 27 ++++++++++----------------- > mm/sparse-vmemmap.c | 1 - > mm/sparse.c | 17 ++++++++--------- > mm/sparse.h | 6 ------ > scripts/gdb/linux/mm.py | 2 +- > 6 files changed, 20 insertions(+), 35 deletions(-) > > diff --git a/drivers/base/memory.c b/drivers/base/memory.c > index 5eead3346f1e3..b0338de2f1d82 100644 > --- a/drivers/base/memory.c > +++ b/drivers/base/memory.c > @@ -972,7 +972,7 @@ void __init memory_dev_init(void) > * block so that it can be covered. > */ > block_id = ULONG_MAX; > - for_each_present_section_nr(0, nr) { > + for_each_early_section_nr(0, nr) { > if (block_id != ULONG_MAX && memory_block_id(nr) == block_id) > continue; > > diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h > index e0fac344f6ac2..62cff59dd80c4 100644 > --- a/include/linux/mmzone.h > +++ b/include/linux/mmzone.h > @@ -2084,7 +2084,6 @@ static inline struct mem_section *__nr_to_section(unsigned long nr) > * accommodate SECTION_MAP_LAST_BIT. We use BUILD_BUG_ON() to ensure this. > */ > enum { > - SECTION_MARKED_PRESENT_BIT, > SECTION_HAS_MEM_MAP_BIT, > SECTION_IS_ONLINE_BIT, > SECTION_IS_EARLY_BIT, > @@ -2094,7 +2093,6 @@ enum { > SECTION_MAP_LAST_BIT, > }; > > -#define SECTION_MARKED_PRESENT BIT(SECTION_MARKED_PRESENT_BIT) > #define SECTION_HAS_MEM_MAP BIT(SECTION_HAS_MEM_MAP_BIT) > #define SECTION_IS_ONLINE BIT(SECTION_IS_ONLINE_BIT) > #define SECTION_IS_EARLY BIT(SECTION_IS_EARLY_BIT) > @@ -2111,16 +2109,6 @@ static inline struct page *__section_mem_map_addr(struct mem_section *section) > return (struct page *)map; > } > > -static inline int present_section(const struct mem_section *section) > -{ > - return (section && (section->section_mem_map & SECTION_MARKED_PRESENT)); > -} > - > -static inline int present_section_nr(unsigned long nr) > -{ > - return present_section(__nr_to_section(nr)); > -} > - > static inline int valid_section(const struct mem_section *section) > { > return (section && (section->section_mem_map & SECTION_HAS_MEM_MAP)); > @@ -2136,6 +2124,11 @@ static inline int valid_section_nr(unsigned long nr) > return valid_section(__nr_to_section(nr)); > } > > +static inline int early_section_nr(unsigned long nr) > +{ > + return early_section(__nr_to_section(nr)); > +} > + > static inline int online_section(const struct mem_section *section) > { > return (section && (section->section_mem_map & SECTION_IS_ONLINE)); > @@ -2315,20 +2308,20 @@ static inline unsigned long next_valid_pfn(unsigned long pfn, unsigned long end_ > > #endif > > -static inline unsigned long next_present_section_nr(unsigned long section_nr) > +static inline unsigned long next_early_section_nr(unsigned long section_nr) > { > while (++section_nr <= __highest_used_section_nr) { > - if (present_section_nr(section_nr)) > + if (early_section_nr(section_nr)) > return section_nr; > } > > return -1; > } > > -#define for_each_present_section_nr(start, section_nr) \ > - for (section_nr = next_present_section_nr(start - 1); \ > +#define for_each_early_section_nr(start, section_nr) \ > + for (section_nr = next_early_section_nr(start - 1); \ > section_nr != -1; \ > - section_nr = next_present_section_nr(section_nr)) > + section_nr = next_early_section_nr(section_nr)) > > /* > * These are _only_ used during initialisation, therefore they > diff --git a/mm/sparse-vmemmap.c b/mm/sparse-vmemmap.c > index e62e6aa07f126..5aba058df6b67 100644 > --- a/mm/sparse-vmemmap.c > +++ b/mm/sparse-vmemmap.c > @@ -890,7 +890,6 @@ int __meminit sparse_add_section(int nid, unsigned long start_pfn, > page_init_poison(memmap, sizeof(struct page) * nr_pages); > > ms = __nr_to_section(section_nr); > - __section_mark_present(ms, section_nr); > > /* Align memmap to section boundary in the subsection case */ > if (section_nr_to_pfn(section_nr) != start_pfn) > diff --git a/mm/sparse.c b/mm/sparse.c > index 2d0f2db34f4cf..344acaaed94db 100644 > --- a/mm/sparse.c > +++ b/mm/sparse.c > @@ -170,13 +170,14 @@ static void __init mminit_validate_memmodel_limits(unsigned long *start_pfn, > */ > unsigned long __highest_used_section_nr; > > -static inline unsigned long first_present_section_nr(void) > +static inline unsigned long first_early_section_nr(void) > { > - return next_present_section_nr(-1); > + return next_early_section_nr(-1); > } > > void __init sparse_sections_init(void) > { > + const unsigned long flags = SECTION_IS_EARLY | SECTION_IS_ONLINE; > unsigned long pfn, start_pfn, end_pfn, section_nr; > int i, nid; > > @@ -196,9 +197,7 @@ void __init sparse_sections_init(void) > continue; > > set_section_nid(section_nr, nid); > - ms->section_mem_map = sparse_encode_early_nid(nid) | > - SECTION_IS_ONLINE; > - __section_mark_present(ms, section_nr); > + ms->section_mem_map = sparse_encode_early_nid(nid) | flags; > } > } > __highest_used_section_nr = section_nr; > @@ -231,7 +230,7 @@ static void __init sparse_metadata_init_nid(int nid, > if (!usage) > panic("Failed to allocate usemap for node %d\n", nid); > > - for_each_present_section_nr(start_section_nr, section_nr) { > + for_each_early_section_nr(start_section_nr, section_nr) { > unsigned long pfn = section_nr_to_pfn(section_nr); > struct page *mem_map; > > @@ -246,18 +245,18 @@ static void __init sparse_metadata_init_nid(int nid, > memmap_boot_pages_add(section_nr_vmemmap_pages(pfn, PAGES_PER_SECTION, > NULL, NULL)); > sparse_init_one_section(__nr_to_section(section_nr), section_nr, > - mem_map, usage, SECTION_IS_EARLY); > + mem_map, usage, 0); > usage = (void *)usage + mem_section_usage_size(); > } > } > > static void __init sparse_metadata_init(void) > { > - unsigned long start_section_nr = first_present_section_nr(); > + unsigned long start_section_nr = first_early_section_nr(); > int nid_begin = sparse_early_nid(__nr_to_section(start_section_nr)); > unsigned long section_nr, nr_sections = 1; > > - for_each_present_section_nr(start_section_nr + 1, section_nr) { > + for_each_early_section_nr(start_section_nr + 1, section_nr) { > const int nid = sparse_early_nid(__nr_to_section(section_nr)); > > if (nid == nid_begin) { > diff --git a/mm/sparse.h b/mm/sparse.h > index a3af4967fd5c5..03351f2467e34 100644 > --- a/mm/sparse.h > +++ b/mm/sparse.h > @@ -114,12 +114,6 @@ static inline void sparse_init_one_section(struct mem_section *ms, > ms->usage = usage; > } > > -static inline void __section_mark_present(struct mem_section *ms, > - unsigned long section_nr) > -{ > - ms->section_mem_map |= SECTION_MARKED_PRESENT; > -} > - > static inline size_t mem_section_usage_size(void) > { > return struct_size_t(struct mem_section_usage, pageblock_flags, > diff --git a/scripts/gdb/linux/mm.py b/scripts/gdb/linux/mm.py > index 193a88d763abf..73d637d28c8e6 100644 > --- a/scripts/gdb/linux/mm.py > +++ b/scripts/gdb/linux/mm.py > @@ -76,7 +76,7 @@ class x86_page_ops(): > self.SECTION_IS_EARLY = 1 << int(gdb.parse_and_eval('SECTION_IS_EARLY_BIT')) > except: > self.SECTION_HAS_MEM_MAP = 1 << 0 > - self.SECTION_IS_EARLY = 1 << 3 > + self.SECTION_IS_EARLY = 1 << 2 Seems a bit strage given the code is: try: self.SECTION_HAS_MEM_MAP = 1 << int(gdb.parse_and_eval('SECTION_HAS_MEM_MAP_BIT')) self.SECTION_IS_EARLY = 1 << int(gdb.parse_and_eval('SECTION_IS_EARLY_BIT')) except: self.SECTION_HAS_MEM_MAP = 1 << 0 self.SECTION_IS_EARLY = 1 << 2 Whereas other variables must be available with no try, e.g.: self.PAGE_OFFSET = int(gdb.parse_and_eval("page_offset_base")) self.VMEMMAP_START = int(gdb.parse_and_eval("vmemmap_base")) self.PHYS_BASE = int(gdb.parse_and_eval("(unsigned long) phys_base")) etc. Is there some weirdness with gdb? Or is it maybe because there are some configs without these symbols maybe? > > self.SUBSECTION_SHIFT = 21 > self.PAGES_PER_SUBSECTION = 1 << (self.SUBSECTION_SHIFT - self.PAGE_SHIFT) > > -- > 2.43.0 > -- Cheers, Lorenzo