If the buffer lock has waiters after the buffer has changed identity then

getnewbuf() needs to drop the buffer in order to wake waiters that might
sleep on the buffer in the context of the old identity.

1 files changed, 11 insertions, 0 deletions

diff --git a/sys/kern/vfs_bio.c b/sys/kern/vfs_bio.c
index 37ef552..904e84c 100644
--- a/sys/kern/vfs_bio.c
+++ b/sys/kern/vfs_bio.c
@@ -1890,6 +1890,17 @@ restart:
 		}
 
 		/*
+		 * Notify any waiters for the buffer lock about
+		 * identity change by freeing the buffer.
+		 */
+		if (qindex == QUEUE_CLEAN && BUF_LOCKWAITERS(bp) > 0) {
+			bp->b_flags |= B_INVAL;
+			bfreekva(bp);
+			brelse(bp);
+			goto restart;
+		}
+
+		/*
 		 * If we are overcomitted then recover the buffer and its
 		 * KVM space.  This occurs in rare situations when multiple
 		 * processes are blocked in getnewbuf() or allocbuf().