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[96.255.20.138]) by smtp.gmail.com with ESMTPSA id af79cd13be357-8cb2b0ce72fsm149707185a.13.2026.02.11.07.16.05 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 11 Feb 2026 07:16:05 -0800 (PST) From: Gregory Price To: linux-cxl@vger.kernel.org Cc: linux-kernel@vger.kernel.org, kernel-team@meta.com, dave@stgolabs.net, jonathan.cameron@huawei.com, dave.jiang@intel.com, alison.schofield@intel.com, vishal.l.verma@intel.com, ira.weiny@intel.com, dan.j.williams@intel.com Subject: [PATCH v2] cxl/memdev: fix deadlock in cxl_memdev_autoremove() on attach failure Date: Wed, 11 Feb 2026 10:16:01 -0500 Message-ID: <20260211151601.2082584-1-gourry@gourry.net> X-Mailer: git-send-email 2.53.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" cxl_memdev_autoremove() takes device_lock(&cxlmd->dev) via guard(device) and then calls cxl_memdev_unregister() when the attach callback was provided but cxl_mem_probe() failed to bind. cxl_memdev_unregister() calls cdev_device_del() device_del() bus_remove_device() device_release_driver() This path is reached when a driver uses the @attach parameter to devm_cxl_add_memdev() and the CXL topology fails to enumerate (e.g. DVSEC range registers decode outside platform-defined CXL ranges, causing the endpoint port probe to fail). Fixes: 29317f8dc6ed ("cxl/mem: Introduce cxl_memdev_attach for CXL-dependen= t operation") Signed-off-by: Gregory Price --- drivers/cxl/core/memdev.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) diff --git a/drivers/cxl/core/memdev.c b/drivers/cxl/core/memdev.c index af3d0cc65138..281acb3b9abe 100644 --- a/drivers/cxl/core/memdev.c +++ b/drivers/cxl/core/memdev.c @@ -1089,10 +1089,8 @@ static int cxlmd_add(struct cxl_memdev *cxlmd, struc= t cxl_dev_state *cxlds) DEFINE_FREE(put_cxlmd, struct cxl_memdev *, if (!IS_ERR_OR_NULL(_T)) put_device(&_T->dev)) =20 -static struct cxl_memdev *cxl_memdev_autoremove(struct cxl_memdev *cxlmd) +static bool cxl_memdev_did_attach(struct cxl_memdev *cxlmd) { - int rc; - /* * If @attach is provided fail if the driver is not attached upon * return. Note that failure here could be the result of a race to @@ -1100,7 +1098,14 @@ static struct cxl_memdev *cxl_memdev_autoremove(stru= ct cxl_memdev *cxlmd) * succeeded and then cxl_mem unbound before the lock is acquired. */ guard(device)(&cxlmd->dev); - if (cxlmd->attach && !cxlmd->dev.driver) { + return (cxlmd->attach && !cxlmd->dev.driver); +} + +static struct cxl_memdev *cxl_memdev_autoremove(struct cxl_memdev *cxlmd) +{ + int rc; + + if (cxl_memdev_did_attach(cxlmd)) { cxl_memdev_unregister(cxlmd); return ERR_PTR(-ENXIO); } --=20 2.47.3