From: Harry Yoo <harry@kernel.org>
To: Brendan Jackman <jackmanb@google.com>,
Andrew Morton <akpm@linux-foundation.org>,
Vlastimil Babka <vbabka@kernel.org>,
Suren Baghdasaryan <surenb@google.com>,
Michal Hocko <mhocko@suse.com>,
Johannes Weiner <hannes@cmpxchg.org>, Zi Yan <ziy@nvidia.com>,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
Clark Williams <clrkwllms@kernel.org>,
Steven Rostedt <rostedt@goodmis.org>,
Alexei Starovoitov <ast@kernel.org>,
Shakeel Butt <shakeel.butt@linux.dev>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
stable@vger.kernel.org, sashiko-bot@kernel.org
Subject: Re: [PATCH 1/2] mm/page_alloc: don't spin_trylock() in NMI on UP
Date: Thu, 16 Jul 2026 11:13:46 +0900 [thread overview]
Message-ID: <7700e867-9fec-48d0-b9b4-d48632fc4808@kernel.org> (raw)
In-Reply-To: <20260715-alloc-nolock-fixes-v1-1-fadc49952dda@google.com>
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On 7/15/26 6:03 PM, Brendan Jackman wrote:
> As noted in can_spin_trylock(), using this is unsafe in this context.
> commit 620b46ed6ae17 ("mm/page_alloc: return NULL early from
> alloc_frozen_pages_nolock() in NMI on UP") fixed this on the alloc side
> but missed the free side.
>
> Impact: If BPF programs using these features in NMI (probably tracing)
> are present on non-SMP builds this might crash the kernel and is
> probably exploitable by local attackers for privilege escalation.
>
> Reported-by: sashiko-bot@kernel.org
> Link: https://sashiko.dev/#/patchset/20260703-alloc-trylock-v5-0-c87b714e19d3%40google.com?part=18
> Cc: stable@vger.kernel.org
> Fixes: 8c57b687e8331 ("mm, bpf: Introduce free_pages_nolock()")
> Signed-off-by: Brendan Jackman <jackmanb@google.com>
> ---
Looks good to me, so:
Reviewed-by: Harry Yoo (Oracle) <harry@kernel.org>
--
Cheers,
Harry / Hyeonggon
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next prev parent reply other threads:[~2026-07-16 2:13 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-07-15 9:03 [PATCH 0/2] mm/page_alloc: fixes for free_pages_nolock() on RT/UP Brendan Jackman
2026-07-15 9:03 ` [PATCH 1/2] mm/page_alloc: don't spin_trylock() in NMI on UP Brendan Jackman
2026-07-15 13:00 ` Vlastimil Babka (SUSE)
2026-07-16 2:13 ` Harry Yoo [this message]
2026-07-15 9:03 ` [PATCH 2/2] mm/page_alloc: don't spin_trylock() when disallowed in free_one_page() Brendan Jackman
2026-07-15 13:07 ` Vlastimil Babka (SUSE)
2026-07-16 2:16 ` Harry Yoo
2026-07-15 19:33 ` [PATCH 0/2] mm/page_alloc: fixes for free_pages_nolock() on RT/UP Andrew Morton
-- strict thread matches above, loose matches on Subject: below --
2026-07-10 10:42 [PATCH 0/2] mm/page_alloc: couple of followups for recent cleanups Brendan Jackman
2026-07-10 10:42 ` [PATCH 1/2] mm/page_alloc: don't spin_trylock() in NMI on UP Brendan Jackman
2026-07-10 10:57 ` sashiko-bot
2026-07-11 0:03 ` Andrew Morton
2026-07-13 14:31 ` Brendan Jackman
2026-07-13 16:15 ` Harry Yoo
2026-07-14 9:52 ` Brendan Jackman
2026-07-14 9:59 ` Brendan Jackman
2026-07-14 11:53 ` Harry Yoo
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