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 2/2] mm/page_alloc: don't spin_trylock() when disallowed in free_one_page()
Date: Thu, 16 Jul 2026 11:16:02 +0900 [thread overview]
Message-ID: <aad6935c-b0b2-4442-8f1c-706aa4a77966@kernel.org> (raw)
In-Reply-To: <20260715-alloc-nolock-fixes-v1-2-fadc49952dda@google.com>
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On 7/15/26 6:03 PM, Brendan Jackman wrote:
> __free_frozen_pages() checks can_spin_trylock() before entering into the
> main free_frozen_page_commit()/free_one_page() path, but before this it
> can get to free_one_page() via the !pcp_allowed_order() and
> MIGRATE_ISOLATE paths.
>
> The !pcp_allowed_order() path depends on usage by callers so might not
> be possible in practice. The MIGRATE_ISOLATE path probably means kernel
> crashes and privilege escalation if anyone ever did memory hotplug and
> BPF tracing on a PREEMPT_RT or !SMP build.
>
> Cc: stable@vger.kernel.org
> Fixes: 8c57b687e8331 ("mm, bpf: Introduce free_pages_nolock()")
> Reported-by: sashiko-bot@kernel.org
> Link: https://sashiko.dev/#/patchset/20260710-spin-trylock-followup-v1-0-affb5fe5ed00%40google.com?part=2
> 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 2:16 UTC|newest]
Thread overview: 8+ 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
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 [this message]
2026-07-15 19:33 ` [PATCH 0/2] mm/page_alloc: fixes for free_pages_nolock() on RT/UP Andrew Morton
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