On 2020/12/19 10:41, Dan Williams wrote:
> There are multiple locations that open-code the release of the last
> range in a device-dax instance. Consolidate this into a new
> dev_dax_trim_range() helper.
>
> This also addresses a kmemleak report:
>
> # cat /sys/kernel/debug/kmemleak
> [..]
> unreferenced object 0xffff976bd46f6240 (size 64):
> comm "ndctl", pid 23556, jiffies 4299514316 (age 5406.733s)
> hex dump (first 32 bytes):
> 00 00 00 00 00 00 00 00 00 00 20 c3 37 00 00 00 .......... .7...
> ff ff ff 7f 38 00 00 00 00 00 00 00 00 00 00 00 ....8...........
> backtrace:
> [<00000000064003cf>] __kmalloc_track_caller+0x136/0x379
> [<00000000d85e3c52>] krealloc+0x67/0x92
> [<00000000d7d3ba8a>] __alloc_dev_dax_range+0x73/0x25c
> [<0000000027d58626>] devm_create_dev_dax+0x27d/0x416
> [<00000000434abd43>] __dax_pmem_probe+0x1c9/0x1000 [dax_pmem_core]
> [<0000000083726c1c>] dax_pmem_probe+0x10/0x1f [dax_pmem]
> [<00000000b5f2319c>] nvdimm_bus_probe+0x9d/0x340 [libnvdimm]
> [<00000000c055e544>] really_probe+0x230/0x48d
> [<000000006cabd38e>] driver_probe_device+0x122/0x13b
> [<0000000029c7b95a>] device_driver_attach+0x5b/0x60
> [<0000000053e5659b>] bind_store+0xb7/0xc3
> [<00000000d3bdaadc>] drv_attr_store+0x27/0x31
> [<00000000949069c5>] sysfs_kf_write+0x4a/0x57
> [<000000004a8b5adf>] kernfs_fop_write+0x150/0x1e5
> [<00000000bded60f0>] __vfs_write+0x1b/0x34
> [<00000000b92900f0>] vfs_write+0xd8/0x1d1
>
> Reported-by: Jane Chu <jane....@oracle.com>
> Cc: Zhen Lei <thunder.leiz...@huawei.com>
> Signed-off-by: Dan Williams <dan.j.willi...@intel.com>
> ---
> drivers/dax/bus.c | 44 +++++++++++++++++++++-----------------------
> 1 file changed, 21 insertions(+), 23 deletions(-)
>
> diff --git a/drivers/dax/bus.c b/drivers/dax/bus.c
> index 9761cb40d4bb..720cd140209f 100644
> --- a/drivers/dax/bus.c
> +++ b/drivers/dax/bus.c
> @@ -367,19 +367,28 @@ void kill_dev_dax(struct dev_dax *dev_dax)
> }
> EXPORT_SYMBOL_GPL(kill_dev_dax);
>
> -static void free_dev_dax_ranges(struct dev_dax *dev_dax)
> +static void trim_dev_dax_range(struct dev_dax *dev_dax)
> {
> + int i = dev_dax->nr_range - 1;
> + struct range *range = &dev_dax->ranges[i].range;
> struct dax_region *dax_region = dev_dax->region;
> - int i;
>
> device_lock_assert(dax_region->dev);
> - for (i = 0; i < dev_dax->nr_range; i++) {
> - struct range *range = &dev_dax->ranges[i].range;
> -
> - __release_region(&dax_region->res, range->start,
> - range_len(range));
> + dev_dbg(&dev_dax->dev, "delete range[%d]: %#llx:%#llx\n", i,
> + (unsigned long long)range->start,
> + (unsigned long long)range->end);
> +
> + __release_region(&dax_region->res, range->start, range_len(range));
> + if (--dev_dax->nr_range == 0) {
> + kfree(dev_dax->ranges);
> + dev_dax->ranges = NULL;
> }
> - dev_dax->nr_range = 0;
> +}
> +
> +static void free_dev_dax_ranges(struct dev_dax *dev_dax)
> +{
> + while (dev_dax->nr_range)
It's better to use READ_ONCE to get the value of dev_dax->nr_range,
to prevent compiler optimization.
> + trim_dev_dax_range(dev_dax);
> }
>
> static void unregister_dev_dax(void *dev)
> @@ -804,15 +813,10 @@ static int alloc_dev_dax_range(struct dev_dax *dev_dax,
> u64 start,
> return 0;
>
> rc = devm_register_dax_mapping(dev_dax, dev_dax->nr_range - 1);
> - if (rc) {
> - dev_dbg(dev, "delete range[%d]: %pa:%pa\n", dev_dax->nr_range -
> 1,
> - &alloc->start, &alloc->end);
> - dev_dax->nr_range--;
> - __release_region(res, alloc->start, resource_size(alloc));
> - return rc;
> - }
> + if (rc)
> + trim_dev_dax_range(dev_dax);
>
> - return 0;
> + return rc;
> }
>
> static int adjust_dev_dax_range(struct dev_dax *dev_dax, struct resource
> *res, resource_size_t size)
> @@ -885,12 +889,7 @@ static int dev_dax_shrink(struct dev_dax *dev_dax,
> resource_size_t size)
> if (shrink >= range_len(range)) {
> devm_release_action(dax_region->dev,
> unregister_dax_mapping, &mapping->dev);
> - __release_region(&dax_region->res, range->start,
> - range_len(range));
> - dev_dax->nr_range--;
> - dev_dbg(dev, "delete range[%d]: %#llx:%#llx\n", i,
> - (unsigned long long) range->start,
> - (unsigned long long) range->end);
> + trim_dev_dax_range(dev_dax);
> to_shrink -= shrink;
> if (!to_shrink)
> break;
> @@ -1267,7 +1266,6 @@ static void dev_dax_release(struct device *dev)
> put_dax(dax_dev);
> free_dev_dax_id(dev_dax);
> dax_region_put(dax_region);
> - kfree(dev_dax->ranges);
> kfree(dev_dax->pgmap);
> kfree(dev_dax);
> }
>
>
> .
>
