From df6cc0a24717c38ac81b5ba1e839c35e74e667dc Mon Sep 17 00:00:00 2001 From: Muchun Song Date: Thu, 24 Sep 2026 10:50:34 +0800 Subject: [PATCH] dax/bus: Return errors for invalid mapping targets After the DAX configuration locking was converted to rwsems, successful lock acquisition leaves rc set to zero in mapping_store(). Two error paths can return this stale value: an unbound region driver and a misaligned range size. The sysfs write therefore reports success without allocating the requested range. Return -ENXIO when the region driver is not bound and -EINVAL when the range size is misaligned. Fixes: c05ae9d85b47 ("dax/bus.c: replace driver-core lock usage by a local rwsem") Assisted-by: LLM Signed-off-by: Muchun Song Reviewed-by: Dave Jiang Reviewed-by: Jianyun Gao Reviewed-by: Alison Schofield Link: https://patch.msgid.link/20260924025035.1265035-2-songmuchun@bytedance.com Signed-off-by: Alison Schofield --- drivers/dax/bus.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/drivers/dax/bus.c b/drivers/dax/bus.c index b809e1a264af..e40c25401cf0 100644 --- a/drivers/dax/bus.c +++ b/drivers/dax/bus.c @@ -1192,7 +1192,7 @@ static ssize_t mapping_store(struct device *dev, struct device_attribute *attr, return rc; if (!dax_region->dev->driver) { up_write(&dax_region_rwsem); - return rc; + return -ENXIO; } rc = down_write_killable(&dax_dev_rwsem); if (rc) { @@ -1201,8 +1201,12 @@ static ssize_t mapping_store(struct device *dev, struct device_attribute *attr, } to_alloc = range_len(&r); - if (alloc_is_aligned(dev_dax, to_alloc)) + if (!alloc_is_aligned(dev_dax, to_alloc)) { + dev_dbg(dev, "%s: size: %zu misaligned\n", __func__, to_alloc); + rc = -EINVAL; + } else { rc = alloc_dev_dax_range(dev_dax, r.start, to_alloc); + } up_write(&dax_dev_rwsem); up_write(&dax_region_rwsem);