From: "David Hildenbrand (Arm)" <david@kernel.org>
To: "Oscar Salvador (SUSE)" <osalvador@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Lorenzo Stoakes <ljs@kernel.org>,
"Liam R. Howlett" <liam@infradead.org>,
Vlastimil Babka <vbabka@kernel.org>,
Mike Rapoport <rppt@kernel.org>,
Suren Baghdasaryan <surenb@google.com>,
Michal Hocko <mhocko@suse.com>, Kairui Song <kasong@tencent.com>,
Qi Zheng <qi.zheng@linux.dev>,
Shakeel Butt <shakeel.butt@linux.dev>,
Barry Song <baohua@kernel.org>,
Axel Rasmussen <axelrasmussen@google.com>,
Yuanchu Xie <yuanchu@google.com>, Wei Xu <weixugc@google.com>,
Baoquan He <baoquan.he@linux.dev>,
Baolin Wang <baolin.wang@linux.alibaba.com>,
Brendan Jackman <brendan.jackman@linux.dev>,
Johannes Weiner <hannes@cmpxchg.org>, Zi Yan <ziy@nvidia.com>,
Oscar Salvador <osalvador@suse.de>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
"Rafael J. Wysocki" <rafael@kernel.org>,
Danilo Krummrich <dakr@kernel.org>,
Jan Kiszka <jan.kiszka@siemens.com>,
Kieran Bingham <kbingham@kernel.org>,
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 08/12] mm/sparse: move __highest_used_section_nr handling
Date: Thu, 10 Sep 2026 15:33:59 +0200 [thread overview]
Message-ID: <db6eb031-4eff-4eb2-bc66-df94e890dba0@kernel.org> (raw)
In-Reply-To: <aqKd1MUgFVHozVWu@localhost.localdomain>
On 9/10/26 14:08, Oscar Salvador (SUSE) wrote:
> On Thu, Sep 10, 2026 at 11:13:18AM +0200, David Hildenbrand (Arm) wrote:
>> If you have something consuming __highest_used_section_nr while concurrently
>> updating it, you might get torn reads/writes that mess up the value on the
>> reader side.
>>
>> For example, mm/compaction.c consuming __highest_used_section_nr.
>
> Right, but I guess that if we get a 'wild' value, at least we are
> guarded by online_section_nr() performing the right thing?
I guess so, I was assuming the only real scenario would be us missing to process
certain sections (which would usually not be the end of the world). Getting
larger values is unlikely when tearing reads/writes I think.
--
Cheers,
David
next prev parent reply other threads:[~2026-09-10 13:34 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-09 13:32 [PATCH 00/12] mm/sparse: remove SECTION_MARKED_PRESENT and further cleanups David Hildenbrand (Arm)
2026-09-09 13:32 ` [PATCH 01/12] mm/sparse: move mem_section init to sparse_extreme_init() David Hildenbrand (Arm)
2026-09-09 17:02 ` Oscar Salvador (SUSE)
2026-09-10 12:52 ` Lorenzo Stoakes (ARM)
2026-09-10 13:13 ` David Hildenbrand (Arm)
2026-09-10 13:33 ` Lorenzo Stoakes (ARM)
2026-09-09 13:32 ` [PATCH 02/12] mm/sparse: refactor sparse_sections_init() David Hildenbrand (Arm)
2026-09-09 17:09 ` Oscar Salvador (SUSE)
2026-09-09 17:18 ` David Hildenbrand (Arm)
2026-09-10 13:29 ` Lorenzo Stoakes (ARM)
2026-09-10 14:30 ` David Hildenbrand (Arm)
2026-09-10 14:38 ` Lorenzo Stoakes (ARM)
2026-09-09 13:32 ` [PATCH 03/12] mm/sparse: move initialization of section metadata to sparse_metadata_init() David Hildenbrand (Arm)
2026-09-09 17:22 ` Oscar Salvador (SUSE)
2026-09-10 13:43 ` Lorenzo Stoakes (ARM)
2026-09-09 13:32 ` [PATCH 04/12] mm/sparse: rename and cleanup sparse_init_nid() David Hildenbrand (Arm)
2026-09-10 7:41 ` Oscar Salvador (SUSE)
2026-09-10 13:46 ` Lorenzo Stoakes (ARM)
2026-09-10 14:29 ` David Hildenbrand (Arm)
2026-09-09 13:32 ` [PATCH 05/12] mm/sparse: cleanup sparse_init_one_section() David Hildenbrand (Arm)
2026-09-10 7:45 ` Oscar Salvador (SUSE)
2026-09-10 13:47 ` Lorenzo Stoakes (ARM)
2026-09-09 13:32 ` [PATCH 06/12] mm/sparse: rename __highest_present_section_nr to __highest_used_section_nr David Hildenbrand (Arm)
2026-09-10 7:56 ` Oscar Salvador (SUSE)
2026-09-10 13:49 ` Lorenzo Stoakes (ARM)
2026-09-09 13:33 ` [PATCH 07/12] mm/sparse: remove pfn_in_present_section() David Hildenbrand (Arm)
2026-09-10 7:59 ` Oscar Salvador (SUSE)
2026-09-10 13:50 ` Lorenzo Stoakes (ARM)
2026-09-09 13:33 ` [PATCH 08/12] mm/sparse: move __highest_used_section_nr handling David Hildenbrand (Arm)
2026-09-09 14:44 ` David Hildenbrand (Arm)
2026-09-10 8:33 ` Oscar Salvador (SUSE)
2026-09-10 9:13 ` David Hildenbrand (Arm)
2026-09-10 12:08 ` Oscar Salvador (SUSE)
2026-09-10 13:33 ` David Hildenbrand (Arm) [this message]
2026-09-10 14:16 ` Lorenzo Stoakes (ARM)
2026-09-10 14:29 ` David Hildenbrand (Arm)
2026-09-10 14:51 ` Lorenzo Stoakes (ARM)
2026-09-09 13:33 ` [PATCH 09/12] mm/sparse: remove SECTION_MARKED_PRESENT David Hildenbrand (Arm)
2026-09-10 12:15 ` Oscar Salvador (SUSE)
2026-09-10 14:32 ` Lorenzo Stoakes (ARM)
2026-09-10 15:11 ` David Hildenbrand (Arm)
2026-09-09 13:33 ` [PATCH 10/12] mm/sparse: remove flags parameter from sparse_init_one_section() David Hildenbrand (Arm)
2026-09-10 12:34 ` Oscar Salvador (SUSE)
2026-09-10 14:34 ` Lorenzo Stoakes (ARM)
2026-09-09 13:33 ` [PATCH 11/12] fs/proc/page: clarify comment in get_max_dump_pfn() David Hildenbrand (Arm)
2026-09-10 12:46 ` Oscar Salvador (SUSE)
2026-09-10 14:41 ` Lorenzo Stoakes (ARM)
2026-09-10 15:14 ` David Hildenbrand (Arm)
2026-09-09 13:33 ` [PATCH 12/12] mm/memory_hotplug: drop CONFIG_HAVE_ARCH_PFN_VALID handling from pfn_to_online_page() David Hildenbrand (Arm)
2026-09-10 14:47 ` Lorenzo Stoakes (ARM)
2026-09-10 15:15 ` David Hildenbrand (Arm)
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