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-rw-r--r--fs/fs-writeback.c5
1 files changed, 4 insertions, 1 deletions
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 38e103506484..128404310fc0 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -701,7 +701,7 @@ EXPORT_SYMBOL_GPL(wbc_account_io);
/**
* inode_congested - test whether an inode is congested
- * @inode: inode to test for congestion
+ * @inode: inode to test for congestion (may be NULL)
* @cong_bits: mask of WB_[a]sync_congested bits to test
*
* Tests whether @inode is congested. @cong_bits is the mask of congestion
@@ -711,6 +711,9 @@ EXPORT_SYMBOL_GPL(wbc_account_io);
* determined by whether the cgwb (cgroup bdi_writeback) for the blkcg
* associated with @inode is congested; otherwise, the root wb's congestion
* state is used.
+ *
+ * @inode is allowed to be NULL as this function is often called on
+ * mapping->host which is NULL for the swapper space.
*/
int inode_congested(struct inode *inode, int cong_bits)
{