---

yaml
---
r: 261737
b: refs/heads/master
c: 5774ed0
h: refs/heads/master
i:
  261735: a007c98
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 6c6e3b828b2a13b923b9465fc4316c5bdc92291f
+refs/heads/master: 5774ed014f02120db9a6945a1ecebeb97c2acccb

trunk/include/linux/shm.h

@@ -95,6 +95,9 @@ struct shmid_kernel /* private to the kernel */
 	pid_t			shm_cprid;
 	pid_t			shm_lprid;
 	struct user_struct	*mlock_user;
+
+	/* The task created the shm object.  NULL if the task is dead. */
+	struct task_struct	*shm_creator;
 };
 
 /* shm_mode upper byte flags */

trunk/ipc/shm.c

@@ -239,7 +239,23 @@ static int shm_try_destroy_current(int id, void *p, void *data)
 	if (IS_ERR(shp))
 		return 0;
 
-	if (shp->shm_cprid != task_tgid_vnr(current)) {
+	if (shp->shm_creator != current) {
+		shm_unlock(shp);
+		return 0;
+	}
+
+	/*
+	 * Mark it as orphaned to destroy the segment when
+	 * kernel.shm_rmid_forced is changed.
+	 * It is noop if the following shm_may_destroy() returns true.
+	 */
+	shp->shm_creator = NULL;
+
+	/*
+	 * Don't even try to destroy it.  If shm_rmid_forced=0 and IPC_RMID
+	 * is not set, it shouldn't be deleted here.
+	 */
+	if (!ns->shm_rmid_forced) {
 		shm_unlock(shp);
 		return 0;
 	}
@@ -255,19 +271,15 @@ static int shm_try_destroy_orphaned(int id, void *p, void *data)
 {
 	struct ipc_namespace *ns = data;
 	struct shmid_kernel *shp = shm_lock(ns, id);
-	struct task_struct *task;
 
 	if (IS_ERR(shp))
 		return 0;
 
 	/*
 	 * We want to destroy segments without users and with already
 	 * exit'ed originating process.
-	 *
-	 * XXX: the originating process may exist in another pid namespace.
 	 */
-	task = find_task_by_vpid(shp->shm_cprid);
-	if (task != NULL) {
+	if (shp->shm_creator != NULL) {
 		shm_unlock(shp);
 		return 0;
 	}
@@ -295,7 +307,7 @@ void exit_shm(struct task_struct *task)
 	if (!nsp)
 		return;
 	ns = nsp->ipc_ns;
-	if (!ns || !ns->shm_rmid_forced)
+	if (!ns)
 		return;
 
 	/* Destroy all already created segments, but not mapped yet */
@@ -494,6 +506,7 @@ static int newseg(struct ipc_namespace *ns, struct ipc_params *params)
 	shp->shm_segsz = size;
 	shp->shm_nattch = 0;
 	shp->shm_file = file;
+	shp->shm_creator = current;
 	/*
 	 * shmid gets reported as "inode#" in /proc/pid/maps.
 	 * proc-ps tools use this. Changing this will break them.