Commit 318c5885 authored Feb 11, 2026 by Gregory Price Committed by Dave Jiang Feb 23, 2026

cxl/memdev: fix deadlock in cxl_memdev_autoremove() on attach failure



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).

Add cxl_memdev_attach_failed() to set the scope of the check correctly.

Reported-by: kreview-c94b85d6d2
Fixes: 29317f8d ("cxl/mem: Introduce cxl_memdev_attach for CXL-dependent operation")
Signed-off-by: Gregory Price <gourry@gourry.net>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Davidlohr Bueso <dave@stgolabs.net>
Link: https://patch.msgid.link/20260211192228.2148713-1-gourry@gourry.net


Signed-off-by: Dave Jiang <dave.jiang@intel.com>

parent 6de23f81

drivers/cxl/core/memdev.c

+9 −4

Original line number	Diff line number	Diff line
		@@ -1089,10 +1089,8 @@ static int cxlmd_add(struct cxl_memdev cxlmd, struct cxl_dev_state cxlds)
		DEFINE_FREE(put_cxlmd, struct cxl_memdev *,
		if (!IS_ERR_OR_NULL(_T)) put_device(&_T->dev))

		static struct cxl_memdev cxl_memdev_autoremove(struct cxl_memdev cxlmd)
		static bool cxl_memdev_attach_failed(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(struct 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_attach_failed(cxlmd)) {
		cxl_memdev_unregister(cxlmd);
		return ERR_PTR(-ENXIO);
		}