From: Baoquan He <baoquan.he@linux.dev>
To: "David Hildenbrand (Arm)" <david@kernel.org>,
k-hagio-ab@nec.com, ruirui.yang@linux.dev
Cc: David Carlier <devnexen@gmail.com>,
akpm@linux-foundation.org, axelrasmussen@google.com,
baohua@kernel.org, baolin.wang@linux.alibaba.com,
brendan.jackman@linux.dev, dakr@kernel.org,
driver-core@lists.linux.dev, gregkh@linuxfoundation.org,
hannes@cmpxchg.org, jan.kiszka@siemens.com, kasong@tencent.com,
kbingham@kernel.org, liam@infradead.org,
linux-cxl@vger.kernel.org, linux-fsdevel@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-mm@kvack.org, ljs@kernel.org,
mhocko@suse.com, osalvador@suse.de, qi.zheng@linux.dev,
rafael@kernel.org, rppt@kernel.org, shakeel.butt@linux.dev,
surenb@google.com, vbabka@kernel.org, weixugc@google.com,
yuanchu@google.com, ziy@nvidia.com,
devel@lists.crash-utility.osci.io
Subject: Re: [PATCH v2 10/13] mm/sparse: remove SECTION_MARKED_PRESENT
Date: Mon, 28 Sep 2026 16:31:51 +0800 [thread overview]
Message-ID: <arol9w7G3vupIVZ7@MiWiFi-R3L-srv> (raw)
In-Reply-To: <655c509e-318f-48bc-8183-2b1274dd05ac@kernel.org>
On 09/28/26 at 09:28am, David Hildenbrand (Arm) wrote:
> On 9/27/26 21:20, David Carlier wrote:
> > On Mon, Sep 21, 2026 at 09:59:02PM +0200, David Hildenbrand (Arm) wrote:
> >> enum {
> >> - SECTION_MARKED_PRESENT_BIT,
> >> SECTION_HAS_MEM_MAP_BIT,
> >> SECTION_IS_ONLINE_BIT,
> >> SECTION_IS_EARLY_BIT,
> >
> > Hi David,
>
> Hi!
>
> >
> > It seems dropping SECTION_MARKED_PRESENT_BIT shifts the other section flags down
> > one bit. crash hardcodes SECTION_HAS_MEM_MAP as (1UL << 1) in
> > pfn_to_map(), so it now tests SECTION_IS_ONLINE: offline and
> > ZONE_DEVICE sections no longer resolve to a struct page. makedumpfile
> > only checks bit 0 and is fine.
>
> Thanks. To be expected when relying on kernel internals.
>
> Which makes me wonder why makedumpfile
> (https://github.com/makedumpfile/makedumpfile) not require any such information.
Makedumpfile requires it too, while it doesn't ask for HAS_MEM_MAP. So
checking MARKED_PRESENT becomes checking HAS_MEM_MAP's value, it luckily
works.
# git grep MARKED_PRESENT
makedumpfile.c: if (!(map_mask & SECTION_MARKED_PRESENT)) {
makedumpfile.h:#define SECTION_MARKED_PRESENT (1UL<<0)
Add makedumpfile maintainer Kazu here.
And add Dave Young here since I heard he is taking over Crash maintenance
as a volunteer.
>
> >
> > Keep bit 0 reserved, or export the bits via vmcoreinfo?
> We could export it, or crash can simply detect the change based on the kernel
> version. I remember the latter was done in makedumpfile in the past (although we
> export it).
>
> I can send a separate patch to export it.
>
> --
> Cheers,
>
> David
next prev parent reply other threads:[~2026-09-28 8:32 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-21 19:58 [PATCH v2 00/13] mm/sparse: remove SECTION_MARKED_PRESENT and further cleanups David Hildenbrand (Arm)
2026-09-21 19:58 ` [PATCH v2 01/13] mm/sparse: move mem_section init to sparse_extreme_init() David Hildenbrand (Arm)
2026-09-21 23:12 ` Zi Yan
2026-09-21 19:58 ` [PATCH v2 02/13] mm/sparse: refactor sparse_sections_init() David Hildenbrand (Arm)
2026-09-21 19:58 ` [PATCH v2 03/13] mm/sparse: move initialization of section metadata to sparse_metadata_init() David Hildenbrand (Arm)
2026-09-21 19:58 ` [PATCH v2 04/13] mm/sparse: rename and cleanup sparse_init_nid() David Hildenbrand (Arm)
2026-09-21 19:58 ` [PATCH v2 05/13] mm/sparse: cleanup sparse_init_one_section() David Hildenbrand (Arm)
2026-09-21 19:58 ` [PATCH v2 06/13] mm/sparse: rename __highest_present_section_nr to __highest_used_section_nr David Hildenbrand (Arm)
2026-09-21 19:58 ` [PATCH v2 07/13] mm/sparse: remove pfn_in_present_section() David Hildenbrand (Arm)
2026-09-21 19:59 ` [PATCH v2 08/13] mm/sparse: move __highest_used_section_nr handling David Hildenbrand (Arm)
2026-09-22 4:24 ` Oscar Salvador (SUSE)
2026-09-22 10:22 ` David Hildenbrand (Arm)
2026-09-21 19:59 ` [PATCH v2 09/13] scripts/gdb: mm.py: remove fallbacks for SECTION_HAS_MEM_MAP and SECTION_IS_EARLY David Hildenbrand (Arm)
2026-09-22 6:49 ` Seongjun Hong
2026-09-21 19:59 ` [PATCH v2 10/13] mm/sparse: remove SECTION_MARKED_PRESENT David Hildenbrand (Arm)
2026-09-27 19:20 ` David Carlier
2026-09-28 7:28 ` David Hildenbrand (Arm)
2026-09-28 8:01 ` Dave Young
2026-09-28 8:50 ` David Hildenbrand (Arm)
2026-09-28 8:31 ` Baoquan He [this message]
2026-09-21 19:59 ` [PATCH v2 11/13] mm/sparse: remove flags parameter from sparse_init_one_section() David Hildenbrand (Arm)
2026-09-21 19:59 ` [PATCH v2 12/13] fs/proc/page: clarify comment in get_max_dump_pfn() David Hildenbrand (Arm)
2026-09-21 19:59 ` [PATCH v2 13/13] mm/memory_hotplug: drop CONFIG_HAVE_ARCH_PFN_VALID handling from pfn_to_online_page() David Hildenbrand (Arm)
2026-09-22 4:25 ` Oscar Salvador (SUSE)
2026-09-21 22:53 ` [PATCH v2 00/13] mm/sparse: remove SECTION_MARKED_PRESENT and further cleanups Andrew Morton
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