Merge branch 'linus' into x86/urgent

Required to queue a dependent fix.

1 files changed, 41 insertions, 1 deletions

diff --git a/drivers/infiniband/core/uverbs_main.c b/drivers/infiniband/core/uverbs_main.c
index 4445d8ee9314..3ae2339dd27a 100644
--- a/drivers/infiniband/core/uverbs_main.c
+++ b/drivers/infiniband/core/uverbs_main.c
@@ -41,6 +41,8 @@
 #include <linux/fs.h>
 #include <linux/poll.h>
 #include <linux/sched.h>
+#include <linux/sched/mm.h>
+#include <linux/sched/task.h>
 #include <linux/file.h>
 #include <linux/cdev.h>
 #include <linux/anon_inodes.h>
@@ -1090,6 +1092,44 @@ err:
 	return;
 }
 
+static void ib_uverbs_disassociate_ucontext(struct ib_ucontext *ibcontext)
+{
+	struct ib_device *ib_dev = ibcontext->device;
+	struct task_struct *owning_process  = NULL;
+	struct mm_struct   *owning_mm       = NULL;
+
+	owning_process = get_pid_task(ibcontext->tgid, PIDTYPE_PID);
+	if (!owning_process)
+		return;
+
+	owning_mm = get_task_mm(owning_process);
+	if (!owning_mm) {
+		pr_info("no mm, disassociate ucontext is pending task termination\n");
+		while (1) {
+			put_task_struct(owning_process);
+			usleep_range(1000, 2000);
+			owning_process = get_pid_task(ibcontext->tgid,
+						      PIDTYPE_PID);
+			if (!owning_process ||
+			    owning_process->state == TASK_DEAD) {
+				pr_info("disassociate ucontext done, task was terminated\n");
+				/* in case task was dead need to release the
+				 * task struct.
+				 */
+				if (owning_process)
+					put_task_struct(owning_process);
+				return;
+			}
+		}
+	}
+
+	down_write(&owning_mm->mmap_sem);
+	ib_dev->disassociate_ucontext(ibcontext);
+	up_write(&owning_mm->mmap_sem);
+	mmput(owning_mm);
+	put_task_struct(owning_process);
+}
+
 static void ib_uverbs_free_hw_resources(struct ib_uverbs_device *uverbs_dev,
 					struct ib_device *ib_dev)
 {
@@ -1130,7 +1170,7 @@ static void ib_uverbs_free_hw_resources(struct ib_uverbs_device *uverbs_dev,
 			 * (e.g mmput).
 			 */
 			ib_uverbs_event_handler(&file->event_handler, &event);
-			ib_dev->disassociate_ucontext(ucontext);
+			ib_uverbs_disassociate_ucontext(ucontext);
 			mutex_lock(&file->cleanup_mutex);
 			ib_uverbs_cleanup_ucontext(file, ucontext, true);
 			mutex_unlock(&file->cleanup_mutex);