From: Jonathan Cameron <jonathan.cameron@huawei.com>
To: Sungwoo Kim <iam@sung-woo.kim>
Cc: Davidlohr Bueso <dave@stgolabs.net>,
Dave Jiang <dave.jiang@intel.com>,
Alison Schofield <alison.schofield@intel.com>,
Vishal Verma <vishal.l.verma@intel.com>,
Ira Weiny <ira.weiny@intel.com>,
Dan Williams <dan.j.williams@intel.com>,
Ben Widawsky <bwidawsk@kernel.org>, <daveti@purdue.edu>,
<linux-cxl@vger.kernel.org>, <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] cxl/region: Fix a race bug in delete_region_store
Date: Mon, 9 Mar 2026 12:00:53 +0000 [thread overview]
Message-ID: <20260309120053.000031cc@huawei.com> (raw)
In-Reply-To: <20260308185958.2453707-2-iam@sung-woo.kim>
On Sun, 8 Mar 2026 14:59:58 -0400
Sungwoo Kim <iam@sung-woo.kim> wrote:
> A race exists when two concurrent sysfs writes to delete_region specify
> the same region name. Both calls succeed in cxl_find_region_by_name()
> (which only does device_find_child_by_name and takes a reference), and
> both then proceed to call devm_release_action(). The first call atomically
> removes and releases the devres entry successfully. The second call finds
> no matching entry, causing devres_release() to return -ENOENT, which trips
> the WARN_ON.
>
> Fix this by replacing devm_release_action() with devm_remove_action_nowarn()
> followed by a manual call to unregister_region(). devm_remove_action_nowarn()
> removes the devres tracking entry and returns an error code.
Naive question (or just me being lazy). Why can't we take the
write lock on cxl_rwsem.region?
Jonathan
next prev parent reply other threads:[~2026-03-09 12:00 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-03-08 18:59 [PATCH] cxl/region: Fix a race bug in delete_region_store Sungwoo Kim
2026-03-09 12:00 ` Jonathan Cameron [this message]
2026-03-09 17:56 ` Sungwoo Kim
2026-03-09 18:10 ` Jonathan Cameron
2026-03-09 20:32 ` Ira Weiny
2026-03-10 18:36 ` Davidlohr Bueso
2026-03-10 22:53 ` Dan Williams
2026-03-11 6:55 ` Sungwoo Kim
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