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b=APzQsnpc/h0TBf+axgiDQYvBy+wydioxquGex71GmFHrrUzUss9Jqe4R0nBNBFD57 IkCliixQ1AD0aHHxSi+oA8DYzXAoN8ZWonS0MKSDG5to2hI71SIAAv4rx85z8QO7fI s4cbWijxgYqZJf0Z/cCzL0d3sHt8Ym/7IJNKBh/5uvcxtSGfX+2tT5UUfwpkyyDcia DlQ6/CV9FPocX5l9sQieAvWX3wYAv7zy8g+gxoiu/uHrH/HaO+bjT1wdXClhMgjP76 pk9W36b3NDKzT4dqiFZrWCMKAEQAlcTrNv/vQfu2o9FSSG234j+mquLdOvVz0/YO0a 3JnOmwcx4/Gpw== Message-ID: Date: Thu, 16 Jul 2026 11:16:02 +0900 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 2/2] mm/page_alloc: don't spin_trylock() when disallowed in free_one_page() 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-v1-2-fadc49952dda@google.com> Content-Language: en-US From: Harry Yoo In-Reply-To: <20260715-alloc-nolock-fixes-v1-2-fadc49952dda@google.com> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="------------wz9HOl6nPDiKXr07fOYppyiX" X-Stat-Signature: pdhubarm3impckonoiu5eyci1u4yadeh X-Rspamd-Queue-Id: 5B0B0A000C X-Rspam-User: X-Rspamd-Server: rspam07 X-HE-Tag: 1784168169-257865 X-HE-Meta: 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 uK3SyPZk 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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) --------------wz9HOl6nPDiKXr07fOYppyiX Content-Type: multipart/mixed; boundary="------------dH64BqDFOVjTDMP3JqgnEybF"; 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: Subject: Re: [PATCH 2/2] mm/page_alloc: don't spin_trylock() when disallowed in free_one_page() References: <20260715-alloc-nolock-fixes-v1-0-fadc49952dda@google.com> <20260715-alloc-nolock-fixes-v1-2-fadc49952dda@google.com> In-Reply-To: <20260715-alloc-nolock-fixes-v1-2-fadc49952dda@google.com> --------------dH64BqDFOVjTDMP3JqgnEybF Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable On 7/15/26 6:03 PM, Brendan Jackman wrote: > __free_frozen_pages() checks can_spin_trylock() before entering into th= e > 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. >=20 > 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. >=20 > 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=3D2 > Signed-off-by: Brendan Jackman > --- Looks good to me, so: Reviewed-by: Harry Yoo (Oracle) --=20 Cheers, Harry / Hyeonggon --------------dH64BqDFOVjTDMP3JqgnEybF-- --------------wz9HOl6nPDiKXr07fOYppyiX Content-Type: application/pgp-signature; name="OpenPGP_signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="OpenPGP_signature.asc" -----BEGIN PGP SIGNATURE----- iHUEARYKAB0WIQQQ1ub6gR5ogjaKRmOGXBN6rc5S1gUCalg+4gAKCRCGXBN6rc5S 1hTBAPsGl6Hne7o/jv65k9wae2cQ0p9eX3JNE4A50yekAYolMQEAgBTot7X6zAo6 KUsEjPVelda4zLtByH+fmyjeXZxYdgI= =vued -----END PGP SIGNATURE----- --------------wz9HOl6nPDiKXr07fOYppyiX--