mm: Fix devm_memremap_pages() collision handling

If devm_memremap_pages() detects a collision while adding entries
to the radix-tree, we call pgmap_radix_release(). Unfortunately,
the function removes *all* entries for the range -- including the
entries that caused the collision in the first place.

Modify pgmap_radix_release() to take an additional argument to
indicate where to stop, so that only newly added entries are removed
from the tree.

Cc: <stable@vger.kernel.org>
Fixes: 9476df7d80df ("mm: introduce find_dev_pagemap()")
Signed-off-by: Jan H. Schönherr <jschoenh@amazon.de>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

1 files changed, 7 insertions, 4 deletions

diff --git a/kernel/memremap.c b/kernel/memremap.c
index 4ef97525a4ff..4849be5f9b3c 100644
--- a/kernel/memremap.c
+++ b/kernel/memremap.c
@@ -241,13 +241,16 @@ int device_private_entry_fault(struct vm_area_struct *vma,
 EXPORT_SYMBOL(device_private_entry_fault);
 #endif /* CONFIG_DEVICE_PRIVATE */
 
-static void pgmap_radix_release(struct resource *res)
+static void pgmap_radix_release(struct resource *res, unsigned long end_pgoff)
 {
         unsigned long pgoff, order;
 
         mutex_lock(&pgmap_lock);
-        foreach_order_pgoff(res, order, pgoff)
+        foreach_order_pgoff(res, order, pgoff) {
+                if (pgoff >= end_pgoff)
+                        break;
                 radix_tree_delete(&pgmap_radix, PHYS_PFN(res->start) + pgoff);
+        }
         mutex_unlock(&pgmap_lock);
 
         synchronize_rcu();
@@ -302,7 +305,7 @@ static void devm_memremap_pages_release(void *data)
         mem_hotplug_done();
 
         untrack_pfn(NULL, PHYS_PFN(align_start), align_size);
-        pgmap_radix_release(res);
+        pgmap_radix_release(res, -1);
         dev_WARN_ONCE(dev, pgmap->altmap.alloc,
                       "%s: failed to free all reserved pages\n", __func__);
 }
@@ -418,7 +421,7 @@ void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap)
         untrack_pfn(NULL, PHYS_PFN(align_start), align_size);
  err_pfn_remap:
  err_radix:
-        pgmap_radix_release(res);
+        pgmap_radix_release(res, pgoff);
         devres_free(pgmap);
         return ERR_PTR(error);
 }