Merge branch 'libnvdimm-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm

Pull nvdimm fixes from Dan Williams:
 "A small crop of lockdep, sleeping while atomic, and other fixes /
  band-aids in advance of the full-blown reworks targeting the next
  merge window. The largest change here is "libnvdimm: fix blk free
  space accounting" which deletes a pile of buggy code that better
  testing would have caught before merging. The next change that is
  borderline too big for a late rc is switching the device-dax locking
  from rcu to srcu, I couldn't think of a smaller way to make that fix.

  The __copy_user_nocache fix will have a full replacement in 4.12 to
  move those pmem special case considerations into the pmem driver. The
  "libnvdimm: band aid btt vs clear poison locking" commit admits that
  our error clearing support for btt went in broken, so we just disable
  it in 4.11 and -stable. A replacement / full fix is in the pipeline
  for 4.12

  Some of these would have been caught earlier had DEBUG_ATOMIC_SLEEP
  been enabled on my development station. I wonder if we should have:

      config DEBUG_ATOMIC_SLEEP
        default PROVE_LOCKING

  ...since I mistakenly thought I got both with PROVE_LOCKING=y.

  These have received a build success notification from the 0day robot,
  and some have appeared in a -next release with no reported issues"

* 'libnvdimm-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm:
  x86, pmem: fix broken __copy_user_nocache cache-bypass assumptions
  device-dax: switch to srcu, fix rcu_read_lock() vs pte allocation
  libnvdimm: band aid btt vs clear poison locking
  libnvdimm: fix reconfig_mutex, mmap_sem, and jbd2_handle lockdep splat
  libnvdimm: fix blk free space accounting
  acpi, nfit, libnvdimm: fix interleave set cookie calculation (64-bit comparison)

1 files changed, 7 insertions, 6 deletions

diff --git a/drivers/dax/dax.c b/drivers/dax/dax.c
index 80c6db279ae1..806f180c80d8 100644
--- a/drivers/dax/dax.c
+++ b/drivers/dax/dax.c
@@ -25,6 +25,7 @@
 #include "dax.h"
 
 static dev_t dax_devt;
+DEFINE_STATIC_SRCU(dax_srcu);
 static struct class *dax_class;
 static DEFINE_IDA(dax_minor_ida);
 static int nr_dax = CONFIG_NR_DEV_DAX;
@@ -60,7 +61,7 @@ struct dax_region {
  * @region - parent region
  * @dev - device backing the character device
  * @cdev - core chardev data
- * @alive - !alive + rcu grace period == no new mappings can be established
+ * @alive - !alive + srcu grace period == no new mappings can be established
  * @id - child id in the region
  * @num_resources - number of physical address extents in this device
  * @res - array of physical address ranges
@@ -569,7 +570,7 @@ static int __dax_dev_pud_fault(struct dax_dev *dax_dev, struct vm_fault *vmf)
 static int dax_dev_huge_fault(struct vm_fault *vmf,
 		enum page_entry_size pe_size)
 {
-	int rc;
+	int rc, id;
 	struct file *filp = vmf->vma->vm_file;
 	struct dax_dev *dax_dev = filp->private_data;
 
@@ -578,7 +579,7 @@ static int dax_dev_huge_fault(struct vm_fault *vmf,
 			? "write" : "read",
 			vmf->vma->vm_start, vmf->vma->vm_end);
 
-	rcu_read_lock();
+	id = srcu_read_lock(&dax_srcu);
 	switch (pe_size) {
 	case PE_SIZE_PTE:
 		rc = __dax_dev_pte_fault(dax_dev, vmf);
@@ -592,7 +593,7 @@ static int dax_dev_huge_fault(struct vm_fault *vmf,
 	default:
 		return VM_FAULT_FALLBACK;
 	}
-	rcu_read_unlock();
+	srcu_read_unlock(&dax_srcu, id);
 
 	return rc;
 }
@@ -713,11 +714,11 @@ static void unregister_dax_dev(void *dev)
 	 * Note, rcu is not protecting the liveness of dax_dev, rcu is
 	 * ensuring that any fault handlers that might have seen
 	 * dax_dev->alive == true, have completed.  Any fault handlers
-	 * that start after synchronize_rcu() has started will abort
+	 * that start after synchronize_srcu() has started will abort
 	 * upon seeing dax_dev->alive == false.
 	 */
 	dax_dev->alive = false;
-	synchronize_rcu();
+	synchronize_srcu(&dax_srcu);
 	unmap_mapping_range(dax_dev->inode->i_mapping, 0, 0, 1);
 	cdev_del(cdev);
 	device_unregister(dev);