Merge tag 'v6.9-rc1' into sched/core, to pick up fixes and to refresh the branch

Signed-off-by: Ingo Molnar <mingo@kernel.org>

3 files changed, 28 insertions, 7 deletions

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 929fce69f555..0621e4ee31de 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -6647,7 +6647,9 @@ static void __sched notrace __schedule(unsigned int sched_mode)
 	 *     if (signal_pending_state())	    if (p->state & @state)
 	 *
 	 * Also, the membarrier system call requires a full memory barrier
-	 * after coming from user-space, before storing to rq->curr.
+	 * after coming from user-space, before storing to rq->curr; this
+	 * barrier matches a full barrier in the proximity of the membarrier
+	 * system call exit.
 	 */
 	rq_lock(rq, &rf);
 	smp_mb__after_spinlock();
@@ -6718,12 +6720,20 @@ static void __sched notrace __schedule(unsigned int sched_mode)
 		 *
 		 * Here are the schemes providing that barrier on the
 		 * various architectures:
-		 * - mm ? switch_mm() : mmdrop() for x86, s390, sparc, PowerPC.
-		 *   switch_mm() rely on membarrier_arch_switch_mm() on PowerPC.
+		 * - mm ? switch_mm() : mmdrop() for x86, s390, sparc, PowerPC,
+		 *   RISC-V.  switch_mm() relies on membarrier_arch_switch_mm()
+		 *   on PowerPC and on RISC-V.
 		 * - finish_lock_switch() for weakly-ordered
 		 *   architectures where spin_unlock is a full barrier,
 		 * - switch_to() for arm64 (weakly-ordered, spin_unlock
 		 *   is a RELEASE barrier),
+		 *
+		 * The barrier matches a full barrier in the proximity of
+		 * the membarrier system call entry.
+		 *
+		 * On RISC-V, this barrier pairing is also needed for the
+		 * SYNC_CORE command when switching between processes, cf.
+		 * the inline comments in membarrier_arch_switch_mm().
 		 */
 		++*switch_count;
 
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index c8e50fbac345..e8270e2e15cb 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -1831,6 +1831,12 @@ bool should_numa_migrate_memory(struct task_struct *p, struct folio *folio,
 	int last_cpupid, this_cpupid;
 
 	/*
+	 * Cannot migrate to memoryless nodes.
+	 */
+	if (!node_state(dst_nid, N_MEMORY))
+		return false;
+
+	/*
 	 * The pages in slow memory node should be migrated according
 	 * to hot/cold instead of private/shared.
 	 */
diff --git a/kernel/sched/membarrier.c b/kernel/sched/membarrier.c
index 4e715b9b278e..809194cd779f 100644
--- a/kernel/sched/membarrier.c
+++ b/kernel/sched/membarrier.c
@@ -254,7 +254,7 @@ static int membarrier_global_expedited(void)
 		return 0;
 
 	/*
-	 * Matches memory barriers around rq->curr modification in
+	 * Matches memory barriers after rq->curr modification in
 	 * scheduler.
 	 */
 	smp_mb();	/* system call entry is not a mb. */
@@ -304,7 +304,7 @@ static int membarrier_global_expedited(void)
 
 	/*
 	 * Memory barrier on the caller thread _after_ we finished
-	 * waiting for the last IPI. Matches memory barriers around
+	 * waiting for the last IPI. Matches memory barriers before
 	 * rq->curr modification in scheduler.
 	 */
 	smp_mb();	/* exit from system call is not a mb */
@@ -324,6 +324,7 @@ static int membarrier_private_expedited(int flags, int cpu_id)
 		      MEMBARRIER_STATE_PRIVATE_EXPEDITED_SYNC_CORE_READY))
 			return -EPERM;
 		ipi_func = ipi_sync_core;
+		prepare_sync_core_cmd(mm);
 	} else if (flags == MEMBARRIER_FLAG_RSEQ) {
 		if (!IS_ENABLED(CONFIG_RSEQ))
 			return -EINVAL;
@@ -343,8 +344,12 @@ static int membarrier_private_expedited(int flags, int cpu_id)
 		return 0;
 
 	/*
-	 * Matches memory barriers around rq->curr modification in
+	 * Matches memory barriers after rq->curr modification in
 	 * scheduler.
+	 *
+	 * On RISC-V, this barrier pairing is also needed for the
+	 * SYNC_CORE command when switching between processes, cf.
+	 * the inline comments in membarrier_arch_switch_mm().
 	 */
 	smp_mb();	/* system call entry is not a mb. */
 
@@ -420,7 +425,7 @@ out:
 
 	/*
 	 * Memory barrier on the caller thread _after_ we finished
-	 * waiting for the last IPI. Matches memory barriers around
+	 * waiting for the last IPI. Matches memory barriers before
 	 * rq->curr modification in scheduler.
 	 */
 	smp_mb();	/* exit from system call is not a mb */