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[195.250.132.146]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-45b6f0d32a2sm295101005e9.9.2025.09.02.02.51.53 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 02 Sep 2025 02:51:53 -0700 (PDT) Date: Tue, 2 Sep 2025 11:51:52 +0200 From: Michal =?utf-8?Q?Koutn=C3=BD?= To: Ashay Jaiswal Cc: Waiman Long , Tejun Heo , Johannes Weiner , "Peter Zijlstra (Intel)" , cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH] cpuset: prevent freeing unallocated cpumask in hotplug handling Message-ID: References: <20250902-cpuset-free-on-condition-v1-1-f46ffab53eac@quicinc.com> Precedence: bulk X-Mailing-List: cgroups@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="z5d55kat4d54zghq" Content-Disposition: inline In-Reply-To: <20250902-cpuset-free-on-condition-v1-1-f46ffab53eac@quicinc.com> --z5d55kat4d54zghq Content-Type: text/plain; protected-headers=v1; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Subject: Re: [PATCH] cpuset: prevent freeing unallocated cpumask in hotplug handling MIME-Version: 1.0 On Tue, Sep 02, 2025 at 09:56:17AM +0530, Ashay Jaiswal wrote: > In cpuset hotplug handling, temporary cpumasks are allocated only when > running under cgroup v2. The current code unconditionally frees these > masks, which can lead to a crash on cgroup v1 case. >=20 > Free the temporary cpumasks only when they were actually allocated. >=20 > Fixes: 4b842da276a8 ("cpuset: Make CPU hotplug work with partition") > Cc: stable@vger.kernel.org > Signed-off-by: Ashay Jaiswal > --- > kernel/cgroup/cpuset.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) >=20 > diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c > index a78ccd11ce9b43c2e8b0e2c454a8ee845ebdc808..a4f908024f3c0a22628a32f8a= 5b0ae96c7dccbb9 100644 > --- a/kernel/cgroup/cpuset.c > +++ b/kernel/cgroup/cpuset.c > @@ -4019,7 +4019,8 @@ static void cpuset_handle_hotplug(void) > if (force_sd_rebuild) > rebuild_sched_domains_cpuslocked(); > =20 > - free_tmpmasks(ptmp); > + if (on_dfl && ptmp) > + free_tmpmasks(ptmp); > } Can you do=20 if (ptmp) free_tmpmasks(ptmp); so that v2 check in concentrated in one place only? Thanks, Michal --z5d55kat4d54zghq Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iJEEABYKADkWIQRCE24Fn/AcRjnLivR+PQLnlNv4CAUCaLa+KBsUgAAAAAAEAA5t YW51MiwyLjUrMS4xMSwyLDIACgkQfj0C55Tb+Ah3/wD/d3gKmwBoKu8zYX6KDBEq a2AnLu103Jhxtbr7ASDeO10BANTgH2wmfZE7r24LBPVJCATLBptAqRmzsnsxgRKf /n4F =zZFz -----END PGP SIGNATURE----- --z5d55kat4d54zghq--