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Subject[PATCH] driver core: Postpone DMA tear-down until after devres release for probe failure
Date
In commit 376991db4b64 ("driver core: Postpone DMA tear-down until after
devres release"), we changed the ordering of tearing down the device DMA
ops and releasing all the device's resources; this was because the DMA ops
should be maintained until we release the device's managed DMA memories.

However, we have seen another crash on an arm64 system when a
device driver probe fails:

hisi_sas_v3_hw 0000:74:02.0: Adding to iommu group 2
scsi host1: hisi_sas_v3_hw
BUG: Bad page state in process swapper/0 pfn:313f5
page:ffff7e0000c4fd40 count:1 mapcount:0
mapping:0000000000000000 index:0x0
flags: 0xfffe00000001000(reserved)
raw: 0fffe00000001000 ffff7e0000c4fd48 ffff7e0000c4fd48
0000000000000000
raw: 0000000000000000 0000000000000000 00000001ffffffff
0000000000000000
page dumped because: PAGE_FLAGS_CHECK_AT_FREE flag(s) set
bad because of flags: 0x1000(reserved)
Modules linked in:
CPU: 49 PID: 1 Comm: swapper/0 Not tainted
5.1.0-rc1-43081-g22d97fd-dirty #1433
Hardware name: Huawei D06/D06, BIOS Hisilicon D06 UEFI
RC0 - V1.12.01 01/29/2019
Call trace:
dump_backtrace+0x0/0x118
show_stack+0x14/0x1c
dump_stack+0xa4/0xc8
bad_page+0xe4/0x13c
free_pages_check_bad+0x4c/0xc0
__free_pages_ok+0x30c/0x340
__free_pages+0x30/0x44
__dma_direct_free_pages+0x30/0x38
dma_direct_free+0x24/0x38
dma_free_attrs+0x9c/0xd8
dmam_release+0x20/0x28
release_nodes+0x17c/0x220
devres_release_all+0x34/0x54
really_probe+0xc4/0x2c8
driver_probe_device+0x58/0xfc
device_driver_attach+0x68/0x70
__driver_attach+0x94/0xdc
bus_for_each_dev+0x5c/0xb4
driver_attach+0x20/0x28
bus_add_driver+0x14c/0x200
driver_register+0x6c/0x124
__pci_register_driver+0x48/0x50
sas_v3_pci_driver_init+0x20/0x28
do_one_initcall+0x40/0x25c
kernel_init_freeable+0x2b8/0x3c0
kernel_init+0x10/0x100
ret_from_fork+0x10/0x18
Disabling lock debugging due to kernel taint
BUG: Bad page state in process swapper/0 pfn:313f6
page:ffff7e0000c4fd80 count:1 mapcount:0
mapping:0000000000000000 index:0x0
[ 89.322983] flags: 0xfffe00000001000(reserved)
raw: 0fffe00000001000 ffff7e0000c4fd88 ffff7e0000c4fd88
0000000000000000
raw: 0000000000000000 0000000000000000 00000001ffffffff
0000000000000000

The crash occurs for the same reason.

In this case, on the really_probe() failure path, we are still clearing
the DMA ops prior to releasing the device's managed memories.

This patch fixes this issue by reordering the DMA ops teardown and the
call to devres_release_all() on the failure path.

Reported-by: Xiang Chen <chenxiang66@hisilicon.com>
Tested-by: Xiang Chen <chenxiang66@hisilicon.com>
Signed-off-by: John Garry <john.garry@huawei.com>
---

For convenience, here is the 2nd half of really_probe() now:

atomic_inc(&probe_count);
pr_debug("bus: '%s': %s: probing driver %s with device %s\n",
drv->bus->name, __func__, drv->name, dev_name(dev));
WARN_ON(!list_empty(&dev->devres_head));

re_probe:
dev->driver = drv;

/* If using pinctrl, bind pins now before probing */
ret = pinctrl_bind_pins(dev);
if (ret)
goto pinctrl_bind_failed;

if (dev->bus->dma_configure) {
ret = dev->bus->dma_configure(dev);
if (ret)
goto probe_failed;
}

if (driver_sysfs_add(dev)) {
printk(KERN_ERR "%s: driver_sysfs_add(%s) failed\n",
__func__, dev_name(dev));
goto probe_failed;
}

if (dev->pm_domain && dev->pm_domain->activate) {
ret = dev->pm_domain->activate(dev);
if (ret)
goto probe_failed;
}

if (dev->bus->probe) {
ret = dev->bus->probe(dev);
if (ret)
goto probe_failed;
} else if (drv->probe) {
ret = drv->probe(dev);
if (ret)
goto probe_failed;
}

if (test_remove) {
test_remove = false;

if (dev->bus->remove)
dev->bus->remove(dev);
else if (drv->remove)
drv->remove(dev);

devres_release_all(dev);
driver_sysfs_remove(dev);
dev->driver = NULL;
dev_set_drvdata(dev, NULL);
if (dev->pm_domain && dev->pm_domain->dismiss)
dev->pm_domain->dismiss(dev);
pm_runtime_reinit(dev);

goto re_probe;
}

pinctrl_init_done(dev);

if (dev->pm_domain && dev->pm_domain->sync)
dev->pm_domain->sync(dev);

driver_bound(dev);
ret = 1;
pr_debug("bus: '%s': %s: bound device %s to driver %s\n",
drv->bus->name, __func__, dev_name(dev), drv->name);
goto done;

probe_failed:
if (dev->bus)
blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
BUS_NOTIFY_DRIVER_NOT_BOUND, dev);
pinctrl_bind_failed:
device_links_no_driver(dev);
devres_release_all(dev);
arch_teardown_dma_ops(dev);
driver_sysfs_remove(dev);
dev->driver = NULL;
dev_set_drvdata(dev, NULL);
if (dev->pm_domain && dev->pm_domain->dismiss)
dev->pm_domain->dismiss(dev);
pm_runtime_reinit(dev);
dev_pm_set_driver_flags(dev, 0);

switch (ret) {
case -EPROBE_DEFER:
/* Driver requested deferred probing */
dev_dbg(dev, "Driver %s requests probe deferral\n", drv->name);
driver_deferred_probe_add_trigger(dev, local_trigger_count);
break;
case -ENODEV:
case -ENXIO:
pr_debug("%s: probe of %s rejects match %d\n",
drv->name, dev_name(dev), ret);
break;
default:
/* driver matched but the probe failed */
printk(KERN_WARNING
"%s: probe of %s failed with error %d\n",
drv->name, dev_name(dev), ret);
}
/*
* Ignore errors returned by ->probe so that the next driver can try
* its luck.
*/
ret = 0;
done:
atomic_dec(&probe_count);
wake_up(&probe_waitqueue);
return ret;
}

diff --git a/drivers/base/dd.c b/drivers/base/dd.c
index a823f469e53f..0df9b4461766 100644
--- a/drivers/base/dd.c
+++ b/drivers/base/dd.c
@@ -490,7 +490,7 @@ static int really_probe(struct device *dev, struct device_driver *drv)
if (dev->bus->dma_configure) {
ret = dev->bus->dma_configure(dev);
if (ret)
- goto dma_failed;
+ goto probe_failed;
}

if (driver_sysfs_add(dev)) {
@@ -546,14 +546,13 @@ static int really_probe(struct device *dev, struct device_driver *drv)
goto done;

probe_failed:
- arch_teardown_dma_ops(dev);
-dma_failed:
if (dev->bus)
blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
BUS_NOTIFY_DRIVER_NOT_BOUND, dev);
pinctrl_bind_failed:
device_links_no_driver(dev);
devres_release_all(dev);
+ arch_teardown_dma_ops(dev);
driver_sysfs_remove(dev);
dev->driver = NULL;
dev_set_drvdata(dev, NULL);
--
2.17.1
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