From: "Zi Yan" <ziy@nvidia.com>
To: "Gregory Price (Meta)" <gourry@gourry.net>, <linux-mm@kvack.org>
Cc: <linux-trace-kernel@vger.kernel.org>,
<linux-kernel@vger.kernel.org>, <kernel-team@meta.com>,
<akpm@linux-foundation.org>, <david@kernel.org>, <ljs@kernel.org>,
<liam@infradead.org>, <vbabka@kernel.org>, <rppt@kernel.org>,
<surenb@google.com>, <mhocko@suse.com>, <kasong@tencent.com>,
<qi.zheng@linux.dev>, <shakeel.butt@linux.dev>,
<baohua@kernel.org>, <axelrasmussen@google.com>,
<yuanchu@google.com>, <weixugc@google.com>,
<baoquan.he@linux.dev>, <baolin.wang@linux.alibaba.com>,
<rientjes@google.com>, <rostedt@goodmis.org>,
<mhiramat@kernel.org>, <mathieu.desnoyers@efficios.com>,
<muchun.song@linux.dev>, <osalvador@suse.de>,
<joshua.hahnjy@gmail.com>, <rakie.kim@sk.com>,
<ying.huang@linux.alibaba.com>, <brendan.jackman@linux.dev>,
<hannes@cmpxchg.org>, <bigeasy@linutronix.de>,
<clrkwllms@kernel.org>, <nathan@kernel.org>,
<ndesaulniers@google.com>, <morbo@google.com>,
<justinstitt@google.com>, <Bessel.Wang@huawei.com>,
<jiang.liu@huawei.com>, <mgorman@techsingularity.net>,
<anshuman.khandual@arm.com>, <stable@vger.kernel.org>
Subject: Re: [PATCH v5 05/12] mm/mmzone: read the zoneref slot once in zonelist_zone()
Date: Mon, 02 Nov 2026 21:54:13 -0500 [thread overview]
Message-ID: <DML8J0KXM6R5.1QH88IJGA8EU5@nvidia.com> (raw)
In-Reply-To: <20261101021340.2251928-6-gourry@gourry.net>
On Sat Oct 31, 2026 at 10:13 PM EDT, Gregory Price (Meta) wrote:
> Memory hotplug rebuilds zonelists in place while allocations walk them,
> so a zoneref slot can change between two loads of it.
>
> zonelist_zone() loads the slot with a plain access. The compiler may
> load it again later instead of keeping the zone it already read, so a
> caller can check one zone and then use another, or the NULL terminator.
>
> Use READ_ONCE(). Callers that take a zone from a slot and keep using
> it, such as get_page_from_freelist() with ac->preferred_zoneref, need
> that single load.
>
> Fixes: 11cd8638c37f ("mm, page_alloc: remove stop_machine from build_all_zonelists")
> Cc: stable@vger.kernel.org
> Signed-off-by: Gregory Price (Meta) <gourry@gourry.net>
> ---
> include/linux/mmzone.h | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
LGTM.
Acked-by: Zi Yan <ziy@nvidia.com>
--
Best Regards,
Yan, Zi
next prev parent reply other threads:[~2026-11-03 2:54 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-11-01 2:13 [PATCH v5 0/12] mm: fix allocator races with memory hotplug Gregory Price (Meta)
2026-11-01 2:13 ` [PATCH v5 01/12] mm/page_alloc: reset can_retry_reserves when the slowpath restarts Gregory Price (Meta)
2026-11-01 19:52 ` Zi Yan
2026-11-01 2:13 ` [PATCH v5 02/12] mm/page_alloc: keep the pagesets of an empty zone Gregory Price (Meta)
2026-11-01 20:07 ` Zi Yan
2026-11-03 14:57 ` Vlastimil Babka (SUSE)
2026-11-03 16:04 ` Zi Yan
2026-11-01 2:13 ` [PATCH v5 03/12] mm, page_alloc: pass zone pointer to trace_reclaim_retry_zone Gregory Price (Meta)
2026-11-01 20:28 ` Zi Yan
2026-11-01 2:13 ` [PATCH v5 04/12] mm/page_alloc: detect zonelist rebuilds from memory hot-add Gregory Price (Meta)
2026-11-01 20:31 ` Zi Yan
2026-11-01 2:13 ` [PATCH v5 05/12] mm/mmzone: read the zoneref slot once in zonelist_zone() Gregory Price (Meta)
2026-11-03 2:54 ` Zi Yan [this message]
2026-11-01 2:13 ` [PATCH v5 06/12] mm/page_alloc: snapshot the preferred zone against shrink rebuilds Gregory Price (Meta)
2026-11-03 2:56 ` Zi Yan
2026-11-01 2:13 ` [PATCH v5 07/12] mm/mmzone: read each zoneref slot once when filtering by nodemask Gregory Price (Meta)
2026-11-03 3:01 ` Zi Yan
2026-11-03 15:00 ` Vlastimil Babka (SUSE)
2026-11-01 2:13 ` [PATCH v5 08/12] mm/page_alloc: retry allocations that raced with a zonelist rebuild Gregory Price (Meta)
2026-11-01 2:13 ` [PATCH v5 09/12] mm/hugetlb: retry the pool walk when the zonelist is rebuilt Gregory Price (Meta)
2026-11-01 2:13 ` [PATCH v5 10/12] mm/page_alloc: retry alloc_contig_pages() " Gregory Price (Meta)
2026-11-03 3:13 ` Zi Yan
2026-11-01 2:13 ` [PATCH v5 11/12] mm/mempolicy: read the zoneref slot once in mempolicy_slab_node() Gregory Price (Meta)
2026-11-03 3:14 ` Zi Yan
2026-11-01 2:13 ` [PATCH v5 12/12] mm/mmzone: remove zonelist_node_idx() Gregory Price (Meta)
2026-11-03 3:15 ` Zi Yan
2026-11-01 11:00 ` [PATCH v5 0/12] mm: fix allocator races with memory hotplug Vlastimil Babka (SUSE)
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