From: "David Hildenbrand (Arm)" <david@kernel.org>
To: "Gregory Price (Meta)" <gourry@gourry.net>, linux-mm@kvack.org
Cc: linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org,
linux-rt-devel@lists.linux.dev, kernel-team@meta.com,
akpm@linux-foundation.org, mhocko@suse.com, rientjes@google.com,
shakeel.butt@linux.dev, rostedt@goodmis.org, mhiramat@kernel.org,
mathieu.desnoyers@efficios.com, muchun.song@linux.dev,
osalvador@suse.de, ljs@kernel.org, liam@infradead.org,
vbabka@kernel.org, rppt@kernel.org, surenb@google.com,
brendan.jackman@linux.dev, hannes@cmpxchg.org, ziy@nvidia.com,
bigeasy@linutronix.de, clrkwllms@kernel.org,
mgorman@techsingularity.net, anshuman.khandual@arm.com,
Bessel.Wang@huawei.com, jiang.liu@huawei.com
Subject: Re: [PATCH v3 0/8] mm: fix allocator races with memory hotplug
Date: Wed, 28 Oct 2026 09:37:39 +0100 [thread overview]
Message-ID: <5e980194-d892-4b68-80fe-612c910c29d7@kernel.org> (raw)
In-Reply-To: <20261021023940.1940971-1-gourry@gourry.net>
On 10/21/26 04:39, Gregory Price (Meta) wrote:
> Eight fixes for allocator paths that can act on state another CPU is
> updating: zonelists rebuilt by memory hotplug, and the pagesets of a
> zone that offlining empties.
>
> I've packaged these together because they're all related to hotplug.
>
> *** Backport note - Patches 5-7 build on patch 1: without it, their
> retry is compiled out when CONFIG_MEMORY_HOTREMOVE=n.
>
> Most of these race conditions stem from zonelists being re-ordered
> in-place at runtime during hotplug. The result is a mixture of failed
> allocations, NULL dereferences, incorrect placement (GFP_KERNEL in
> ZONE_MOVABLE), node misplacement, or incorrectly allowing hugetlb /
> contig allocations on a node/zone otherwise not eligible.
>
> Most of these are incredibly narrow race conditions, but since the most
> likely impacted machines are VMs with memory hotplug, the narrow
> condition can more easily occur when a vCPU takes a long interrupt / VM
> exit of some kind. I've made all of these race conditions
> deterministics with a kprobe reproduction module described below.
What's the status of this? "memory hotplug" caught my attention, but then then
is all page_alloc material :)
--
Cheers,
David
next prev parent reply other threads:[~2026-10-28 8:37 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-21 2:39 [PATCH v3 0/8] mm: fix allocator races with memory hotplug Gregory Price (Meta)
2026-10-21 2:39 ` [PATCH v3 1/8] mm/page_alloc: detect zonelist rebuilds from memory hot-add Gregory Price (Meta)
2026-10-21 2:39 ` [PATCH v3 2/8] mm/page_alloc: snapshot the preferred zone against shrink rebuilds Gregory Price (Meta)
2026-10-21 2:39 ` [PATCH v3 3/8] mm/mmzone: read each zoneref slot once when filtering by nodemask Gregory Price (Meta)
2026-10-21 2:39 ` [PATCH v3 4/8] mm/page_alloc: pass the zone, not the zoneref, to reclaim_retry_zone Gregory Price (Meta)
2026-10-21 2:39 ` [PATCH v3 5/8] mm/page_alloc: retry allocations that raced with a zonelist rebuild Gregory Price (Meta)
2026-10-22 2:41 ` sashiko-bot
2026-10-21 2:39 ` [PATCH v3 6/8] mm/hugetlb: retry the pool walk when the zonelist is rebuilt Gregory Price (Meta)
2026-10-21 2:39 ` [PATCH v3 7/8] mm/page_alloc: retry alloc_contig_pages() " Gregory Price (Meta)
2026-10-21 2:39 ` [PATCH v3 8/8] mm/page_alloc: keep a zone's pagesets when it goes empty Gregory Price (Meta)
2026-10-21 8:24 ` [PATCH v3 0/8] mm: fix allocator races with memory hotplug David Hildenbrand (Arm)
2026-10-21 13:24 ` Gregory Price (Meta)
2026-10-28 8:37 ` David Hildenbrand (Arm) [this message]
2026-10-28 13:41 ` Gregory Price (Meta)
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