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b=EBjsBetTSLJ/PVXVrqcQdqnyDxxVDV0X2i7wsl6PjjO7XwAqHXbYMpkxNNCLqM3Ag Q7w8Gn4ODpy4hriDiT62lcx4Y99bE45MLrMFL4r2C7pyBxtEKWDVFhMbMABBPohN6x A2KNevJdgn3xL3cHRiXO2U1YEbfY1VR8wr0VV8ejaH+AnymlWRJ2u5Z5+KHf9FqkeW npmW+d2THetZb3DtPP4Kj7716QEjvgDOgqcbSpma/8XdRe/ZGz/9kAvwxx4QlQ6Nqd 75tFh5B6g0eWy6tbgLp4JBH6TSPkajTMH2Rdqzvalp8eACMSLnssTJOlfo3iNK5WGP G8xcyb/3fqcGQ== Message-ID: <7700e867-9fec-48d0-b9b4-d48632fc4808@kernel.org> Date: Thu, 16 Jul 2026 11:13:46 +0900 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 1/2] mm/page_alloc: don't spin_trylock() in NMI on UP To: Brendan Jackman , Andrew Morton , Vlastimil Babka , Suren Baghdasaryan , Michal Hocko , Johannes Weiner , Zi Yan , Sebastian Andrzej Siewior , Clark Williams , Steven Rostedt , Alexei Starovoitov , Shakeel Butt Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org, sashiko-bot@kernel.org References: <20260715-alloc-nolock-fixes-v1-0-fadc49952dda@google.com> <20260715-alloc-nolock-fixes-v1-1-fadc49952dda@google.com> Content-Language: en-US From: Harry Yoo In-Reply-To: <20260715-alloc-nolock-fixes-v1-1-fadc49952dda@google.com> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="------------Ii0HwgF0oUWLgy0EetAZXxlL" X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 20A6A140009 X-Stat-Signature: wrmiuki5gkbzps168h7feawr48wefy7m X-Rspam-User: X-HE-Tag: 1784168037-182522 X-HE-Meta: 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 KR9UdEyI 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --------------Ii0HwgF0oUWLgy0EetAZXxlL Content-Type: multipart/mixed; boundary="------------RMnVot6AwRKrwAyyoZv71EnF"; protected-headers="v1" From: Harry Yoo To: Brendan Jackman , Andrew Morton , Vlastimil Babka , Suren Baghdasaryan , Michal Hocko , Johannes Weiner , Zi Yan , Sebastian Andrzej Siewior , Clark Williams , Steven Rostedt , Alexei Starovoitov , Shakeel Butt Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org, sashiko-bot@kernel.org Message-ID: <7700e867-9fec-48d0-b9b4-d48632fc4808@kernel.org> Subject: Re: [PATCH 1/2] mm/page_alloc: don't spin_trylock() in NMI on UP References: <20260715-alloc-nolock-fixes-v1-0-fadc49952dda@google.com> <20260715-alloc-nolock-fixes-v1-1-fadc49952dda@google.com> In-Reply-To: <20260715-alloc-nolock-fixes-v1-1-fadc49952dda@google.com> --------------RMnVot6AwRKrwAyyoZv71EnF Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable 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. >=20 > 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. >=20 > Reported-by: sashiko-bot@kernel.org > Link: https://sashiko.dev/#/patchset/20260703-alloc-trylock-v5-0-c87b71= 4e19d3%40google.com?part=3D18 > Cc: stable@vger.kernel.org > Fixes: 8c57b687e8331 ("mm, bpf: Introduce free_pages_nolock()") > Signed-off-by: Brendan Jackman > --- Looks good to me, so: Reviewed-by: Harry Yoo (Oracle) --=20 Cheers, Harry / Hyeonggon --------------RMnVot6AwRKrwAyyoZv71EnF-- --------------Ii0HwgF0oUWLgy0EetAZXxlL Content-Type: application/pgp-signature; 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