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 01/12] mm/page_alloc: reset can_retry_reserves when the slowpath restarts
Date: Sun, 01 Nov 2026 14:52:52 -0500 [thread overview]
Message-ID: <DMK4XUPI9V56.399OWZ5IHCOO6@nvidia.com> (raw)
In-Reply-To: <20261101021340.2251928-2-gourry@gourry.net>
On Sat Oct 31, 2026 at 10:13 PM EDT, Gregory Price (Meta) wrote:
> Commit 2c4c3e29897d ("mm/page_alloc: simplify __alloc_pages_slowpath()
> flow") retries an allocation once with reserve_flags when the caller
> becomes eligible for reserves, guarded by can_retry_reserves.
>
> A restart after a cpuset update or a zonelist rebuild retries with
> can_retry_reserves already set to false, so a caller that cannot
> reclaim (GFP_NOWAIT | __GFP_MEMALLOC), fails without trying reserves.
>
> Reset can_retry_reserves on restart. Only a cpuset or zonelist change
> restarts the slowpath, so the retry still runs at most once per change.
>
> With a kprobe helping to make the race deterministic, an allocation
> can be made to return NULL. With this patch the allocation will succeed.
>
> Fixes: 2c4c3e29897d ("mm/page_alloc: simplify __alloc_pages_slowpath() flow")
> Cc: stable@vger.kernel.org
> Signed-off-by: Gregory Price (Meta) <gourry@gourry.net>
> ---
> mm/page_alloc.c | 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:[~2026-11-01 19:53 UTC|newest]
Thread overview: 18+ 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 [this message]
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
2026-11-01 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)
2026-11-01 2:13 ` [PATCH v5 06/12] mm/page_alloc: snapshot the preferred zone against shrink rebuilds Gregory Price (Meta)
2026-11-01 2:13 ` [PATCH v5 07/12] mm/mmzone: read each zoneref slot once when filtering by nodemask Gregory Price (Meta)
2026-11-01 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)
2026-11-01 2:13 ` [PATCH v5 11/12] mm/mempolicy: read the zoneref slot once in mempolicy_slab_node() Gregory Price (Meta)
2026-11-01 2:13 ` [PATCH v5 12/12] mm/mmzone: remove zonelist_node_idx() Gregory Price (Meta)
2026-11-01 11:00 ` [PATCH v5 0/12] mm: fix allocator races with memory hotplug Vlastimil Babka (SUSE)
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