From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2E57036606A; Sat, 12 Sep 2026 07:36:54 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789198616; cv=none; b=g1TAlFGReYF0A5xc1vEAMdpav2H6YVXM7O9+ur998PJFQfBm4QgWoTA7u/BTTrxTyrD8GeDT1ArG71QMXhj7Ot3bHDkpZdJJk9N5BGOdfSAsp6RoX1lhhCwkzInWrWi/Cw1ZXW/THUoT3UbmG63LkZAyF3YDrMnE7E1PmO/OIN0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789198616; c=relaxed/simple; bh=W/CYHRLqTHcDAye/SUasTBNsVsNIBSZ93Drv8ZM1b9c=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=i8M2QjOrBz6Pu9FkM4siIMdZOgxmObXYDSpY037PKt7EJBb2FHibGaYCOjL/pyI659Tbs5Lxo5aVWW41xo1rjIHdyrjX0ceS6SACxz+EM5ofL3pXGolNfAIL+1tdASo4vPIyjNFp9Jhx0Qi1qpmfX+USgc6fuyc7litc0xKUFzc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=u1my/btr; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="u1my/btr" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 895FD1F000FF; Sat, 12 Sep 2026 07:36:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1789198613; bh=etWWreaoIBe5NCe+uvlpYcMXG2KVKqo5TTcB6wFevJY=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=u1my/btrY/pYUyCfjCOysHfcWmB2XC2U/11jFVkgbzvc1LItPermXfpWe1qeUzcbW j1draauwhlDMccIXAeQ0ttcv38Q7gk++ahZaIK3l1Eb7M7w85roESB+wqWI+3y737Z n0jb80VS/U5NisXkVRZrEpkL8rFjawDmsWK0Chg8= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Dave Jiang , John Groves , Alison Schofield , Sasha Levin Subject: [PATCH 7.2 0418/1815] dax/fsdev: dont leave a dangling dev_dax->pgmap on probe failure Date: Sat, 12 Sep 2026 08:36:08 +0200 Message-ID: <20260912065658.708734384@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260912065648.999753832@linuxfoundation.org> References: <20260912065648.999753832@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 7.2-stable review patch. If anyone has any objections, please let me know. ------------------ From: John Groves [ Upstream commit caf906009d12cb21b934f1c4d17cedc6d469429f ] After the dynamic path set dev_dax->pgmap, any later probe failure left dev_dax->pgmap dangling: devres frees the devm_kzalloc'd pgmap on probe failure, and subsequent probe attempts would hit the "dynamic-dax with pre-populated page map" check and fail permanently. Factor pgmap acquisition out into fsdev_acquire_pgmap(), and defer the dev_dax->pgmap assignment until probe can no longer fail. A failed probe now never publishes the pointer at all, so there is nothing to unwind. This also matches kill_dev_dax(), which already clears the dynamic pgmap pointer on unbind: dev_dax->pgmap is now non-NULL only while the pgmap is actually valid. Refactor suggested by Dave Jiang. Fixes: d5406bd458b0a ("dax: add fsdev.c driver for fs-dax on character dax") Reviewed-by: Dave Jiang Signed-off-by: John Groves Link: https://patch.msgid.link/0100019ecc092ca1-ffc7a5fd-1252-4be5-882c-fd5efdc102a9-000000@email.amazonses.com Signed-off-by: Alison Schofield Signed-off-by: Sasha Levin --- drivers/dax/fsdev.c | 77 ++++++++++++++++++++++++++++----------------- 1 file changed, 49 insertions(+), 28 deletions(-) diff --git a/drivers/dax/fsdev.c b/drivers/dax/fsdev.c index dbd722ed7ab05..0fd5e1293d725 100644 --- a/drivers/dax/fsdev.c +++ b/drivers/dax/fsdev.c @@ -219,47 +219,62 @@ static const struct file_operations fsdev_fops = { .release = fsdev_release, }; -static int fsdev_dax_probe(struct dev_dax *dev_dax) +/* + * Acquire the dev_pagemap for probe: the static (pre-populated) one if + * present, or a devm-allocated one for the dynamic case. Note that + * dev_dax->pgmap is not set here; fsdev_dax_probe() sets it only once + * probe succeeds, so a failed probe never leaves a dangling pointer + * to a devres-freed pgmap. + */ +static struct dev_pagemap *fsdev_acquire_pgmap(struct dev_dax *dev_dax) { - struct dax_device *dax_dev = dev_dax->dax_dev; struct device *dev = &dev_dax->dev; struct dev_pagemap *pgmap; - struct inode *inode; - u64 data_offset = 0; - struct cdev *cdev; - void *addr; - int rc, i; + size_t pgmap_size; if (static_dev_dax(dev_dax)) { if (dev_dax->nr_range > 1) { - dev_warn(dev, "static pgmap / multi-range device conflict\n"); - return -EINVAL; + dev_warn(dev, + "static pgmap / multi-range device conflict\n"); + return ERR_PTR(-EINVAL); } pgmap = dev_dax->pgmap; pgmap->vmemmap_shift = 0; - } else { - size_t pgmap_size; + return pgmap; + } - if (dev_dax->pgmap) { - dev_warn(dev, "dynamic-dax with pre-populated page map\n"); - return -EINVAL; - } + if (dev_dax->pgmap) { + dev_warn(dev, "dynamic-dax with pre-populated page map\n"); + return ERR_PTR(-EINVAL); + } - pgmap_size = struct_size(pgmap, ranges, dev_dax->nr_range - 1); - pgmap = devm_kzalloc(dev, pgmap_size, GFP_KERNEL); - if (!pgmap) - return -ENOMEM; + pgmap_size = struct_size(pgmap, ranges, dev_dax->nr_range - 1); + pgmap = devm_kzalloc(dev, pgmap_size, GFP_KERNEL); + if (!pgmap) + return ERR_PTR(-ENOMEM); - pgmap->nr_range = dev_dax->nr_range; - dev_dax->pgmap = pgmap; + pgmap->nr_range = dev_dax->nr_range; + for (int i = 0; i < dev_dax->nr_range; i++) + pgmap->ranges[i] = dev_dax->ranges[i].range; - for (i = 0; i < dev_dax->nr_range; i++) { - struct range *range = &dev_dax->ranges[i].range; + return pgmap; +} - pgmap->ranges[i] = *range; - } - } +static int fsdev_dax_probe(struct dev_dax *dev_dax) +{ + struct dax_device *dax_dev = dev_dax->dax_dev; + struct device *dev = &dev_dax->dev; + struct dev_pagemap *pgmap; + struct inode *inode; + u64 data_offset = 0; + struct cdev *cdev; + void *addr; + int rc, i; + + pgmap = fsdev_acquire_pgmap(dev_dax); + if (IS_ERR(pgmap)) + return PTR_ERR(pgmap); for (i = 0; i < dev_dax->nr_range; i++) { struct range *range = &dev_dax->ranges[i].range; @@ -306,7 +321,7 @@ static int fsdev_dax_probe(struct dev_dax *dev_dax) /* Detect whether the data is at a non-zero offset into the memory */ if (pgmap->range.start != dev_dax->ranges[0].range.start) { u64 phys = dev_dax->ranges[0].range.start; - u64 pgmap_phys = dev_dax->pgmap[0].range.start; + u64 pgmap_phys = pgmap[0].range.start; if (!WARN_ON(pgmap_phys > phys)) data_offset = phys - pgmap_phys; @@ -339,7 +354,13 @@ static int fsdev_dax_probe(struct dev_dax *dev_dax) return rc; run_dax(dax_dev); - return devm_add_action_or_reset(dev, fsdev_kill, dev_dax); + rc = devm_add_action_or_reset(dev, fsdev_kill, dev_dax); + if (rc) + return rc; + + /* Probe can no longer fail; expose the pgmap via dev_dax */ + dev_dax->pgmap = pgmap; + return 0; } static struct dax_device_driver fsdev_dax_driver = { -- 2.53.0