Merge tag 'mm-hotfixes-stable-2024-08-07-18-32' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Pull misc fixes from Andrew Morton:
 "Nine hotfixes. Five are cc:stable, the others either pertain to
  post-6.10 material or aren't considered necessary for earlier kernels.

  Five are MM and four are non-MM. No identifiable theme here - please
  see the individual changelogs"

* tag 'mm-hotfixes-stable-2024-08-07-18-32' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm:
  padata: Fix possible divide-by-0 panic in padata_mt_helper()
  mailmap: update entry for David Heidelberg
  memcg: protect concurrent access to mem_cgroup_idr
  mm: shmem: fix incorrect aligned index when checking conflicts
  mm: shmem: avoid allocating huge pages larger than MAX_PAGECACHE_ORDER for shmem
  mm: list_lru: fix UAF for memory cgroup
  kcov: properly check for softirq context
  MAINTAINERS: Update LTP members and web
  selftests: mm: add s390 to ARCH check

2 files changed, 19 insertions, 3 deletions

diff --git a/kernel/kcov.c b/kernel/kcov.c
index f0a69d402066..274b6b7c718d 100644
--- a/kernel/kcov.c
+++ b/kernel/kcov.c
@@ -161,6 +161,15 @@ static void kcov_remote_area_put(struct kcov_remote_area *area,
 	kmsan_unpoison_memory(&area->list, sizeof(area->list));
 }
 
+/*
+ * Unlike in_serving_softirq(), this function returns false when called during
+ * a hardirq or an NMI that happened in the softirq context.
+ */
+static inline bool in_softirq_really(void)
+{
+	return in_serving_softirq() && !in_hardirq() && !in_nmi();
+}
+
 static notrace bool check_kcov_mode(enum kcov_mode needed_mode, struct task_struct *t)
 {
 	unsigned int mode;
@@ -170,7 +179,7 @@ static notrace bool check_kcov_mode(enum kcov_mode needed_mode, struct task_stru
 	 * so we ignore code executed in interrupts, unless we are in a remote
 	 * coverage collection section in a softirq.
 	 */
-	if (!in_task() && !(in_serving_softirq() && t->kcov_softirq))
+	if (!in_task() && !(in_softirq_really() && t->kcov_softirq))
 		return false;
 	mode = READ_ONCE(t->kcov_mode);
 	/*
@@ -849,7 +858,7 @@ void kcov_remote_start(u64 handle)
 
 	if (WARN_ON(!kcov_check_handle(handle, true, true, true)))
 		return;
-	if (!in_task() && !in_serving_softirq())
+	if (!in_task() && !in_softirq_really())
 		return;
 
 	local_lock_irqsave(&kcov_percpu_data.lock, flags);
@@ -991,7 +1000,7 @@ void kcov_remote_stop(void)
 	int sequence;
 	unsigned long flags;
 
-	if (!in_task() && !in_serving_softirq())
+	if (!in_task() && !in_softirq_really())
 		return;
 
 	local_lock_irqsave(&kcov_percpu_data.lock, flags);
diff --git a/kernel/padata.c b/kernel/padata.c
index 53f4bc912712..0fa6c2895460 100644
--- a/kernel/padata.c
+++ b/kernel/padata.c
@@ -517,6 +517,13 @@ void __init padata_do_multithreaded(struct padata_mt_job *job)
 	ps.chunk_size = max(ps.chunk_size, job->min_chunk);
 	ps.chunk_size = roundup(ps.chunk_size, job->align);
 
+	/*
+	 * chunk_size can be 0 if the caller sets min_chunk to 0. So force it
+	 * to at least 1 to prevent divide-by-0 panic in padata_mt_helper().`
+	 */
+	if (!ps.chunk_size)
+		ps.chunk_size = 1U;
+
 	list_for_each_entry(pw, &works, pw_list)
 		if (job->numa_aware) {
 			int old_node = atomic_read(&last_used_nid);