Subject: Re: [next] arm64: boot failed - next-20220606

From: Roman Gushchin <[email-masked]>
Date: Thu, 9 Jun 2022 10:26:56 -0700

On Tue, Jun 07, 2022 at 11:00:39AM +0530, Naresh Kamboju wrote:
> On Mon, 6 Jun 2022 at 17:16, Naresh Kamboju <[email-masked]> wrote:
> >
> > Linux next-20220606 arm64 boot failed. The kernel boot log is empty.
> > I am bisecting this problem.
> >
> > Reported-by: Linux Kernel Functional Testing <[email-masked]>
> >
> > The initial investigation show that,
> >
> > GOOD: next-20220603
> > BAD:  next-20220606
> >
> > Boot log:
> > Starting kernel ...
> 
> Linux next-20220606 and next-20220607 arm64 boot failed.
> The kernel panic log showing after earlycon.
> 
> Reported-by: Linux Kernel Functional Testing <[email-masked]>

Naresh, can you, please, check if the following patch resolves the issue?
(completely untested except for building)

--

>From 6a454876c9a1886e3cf8e9b66dae19b326f8901a Mon Sep 17 00:00:00 2001
From: Roman Gushchin <[email-masked]>
Date: Thu, 9 Jun 2022 10:03:20 -0700
Subject: [PATCH] mm: kmem: make mem_cgroup_from_obj() vmalloc()-safe

Currently mem_cgroup_from_obj() is not working properly with objects
allocated using vmalloc(). It creates problems in some cases, when
it's called for static objects belonging to  modules or generally
allocated using vmalloc().

This patch makes mem_cgroup_from_obj() safe to be called on objects
allocated using vmalloc().

It also introduces mem_cgroup_from_slab_obj(), which is a faster
version to use in places when we know the object is either a slab
object or a generic slab page (e.g. when adding an object to a lru
list).

Suggested-by: Kefeng Wang <[email-masked]>
Signed-off-by: Roman Gushchin <[email-masked]>
---
 include/linux/memcontrol.h |  6 ++++
 mm/list_lru.c              |  2 +-
 mm/memcontrol.c            | 71 +++++++++++++++++++++++++++-----------
 3 files changed, 57 insertions(+), 22 deletions(-)

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 0d7584e2f335..4d31ce55b1c0 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -1761,6 +1761,7 @@ static inline int memcg_kmem_id(struct mem_cgroup *memcg)
 }
 
 struct mem_cgroup *mem_cgroup_from_obj(void *p);
+struct mem_cgroup *mem_cgroup_from_slab_obj(void *p);
 
 static inline void count_objcg_event(struct obj_cgroup *objcg,
 				     enum vm_event_item idx)
@@ -1858,6 +1859,11 @@ static inline struct mem_cgroup *mem_cgroup_from_obj(void *p)
 	return NULL;
 }
 
+static inline struct mem_cgroup *mem_cgroup_from_slab_obj(void *p)
+{
+	return NULL;
+}
+
 static inline void count_objcg_event(struct obj_cgroup *objcg,
 				     enum vm_event_item idx)
 {
diff --git a/mm/list_lru.c b/mm/list_lru.c
index ba76428ceece..a05e5bef3b40 100644
--- a/mm/list_lru.c
+++ b/mm/list_lru.c
@@ -71,7 +71,7 @@ list_lru_from_kmem(struct list_lru *lru, int nid, void *ptr,
 	if (!list_lru_memcg_aware(lru))
 		goto out;
 
-	memcg = mem_cgroup_from_obj(ptr);
+	memcg = mem_cgroup_from_slab_obj(ptr);
 	if (!memcg)
 		goto out;
 
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 4093062c5c9b..8c408d681377 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -783,7 +783,7 @@ void __mod_lruvec_kmem_state(void *p, enum node_stat_item idx, int val)
 	struct lruvec *lruvec;
 
 	rcu_read_lock();
-	memcg = mem_cgroup_from_obj(p);
+	memcg = mem_cgroup_from_slab_obj(p);
 
 	/*
 	 * Untracked pages have no memcg, no lruvec. Update only the
@@ -2833,27 +2833,9 @@ int memcg_alloc_slab_cgroups(struct slab *slab, struct kmem_cache *s,
 	return 0;
 }
 
-/*
- * Returns a pointer to the memory cgroup to which the kernel object is charged.
- *
- * A passed kernel object can be a slab object or a generic kernel page, so
- * different mechanisms for getting the memory cgroup pointer should be used.
- * In certain cases (e.g. kernel stacks or large kmallocs with SLUB) the caller
- * can not know for sure how the kernel object is implemented.
- * mem_cgroup_from_obj() can be safely used in such cases.
- *
- * The caller must ensure the memcg lifetime, e.g. by taking rcu_read_lock(),
- * cgroup_mutex, etc.
- */
-struct mem_cgroup *mem_cgroup_from_obj(void *p)
+static __always_inline
+struct mem_cgroup *mem_cgroup_from_obj_folio(struct folio *folio, void *p)
 {
-	struct folio *folio;
-
-	if (mem_cgroup_disabled())
-		return NULL;
-
-	folio = virt_to_folio(p);
-
 	/*
 	 * Slab objects are accounted individually, not per-page.
 	 * Memcg membership data for each individual object is saved in
@@ -2886,6 +2868,53 @@ struct mem_cgroup *mem_cgroup_from_obj(void *p)
 	return page_memcg_check(folio_page(folio, 0));
 }
 
+/*
+ * Returns a pointer to the memory cgroup to which the kernel object is charged.
+ *
+ * A passed kernel object can be a slab object, vmalloc object or a generic
+ * kernel page, so different mechanisms for getting the memory cgroup pointer
+ * should be used.
+ *
+ * In certain cases (e.g. kernel stacks or large kmallocs with SLUB) the caller
+ * can not know for sure how the kernel object is implemented.
+ * mem_cgroup_from_obj() can be safely used in such cases.
+ *
+ * The caller must ensure the memcg lifetime, e.g. by taking rcu_read_lock(),
+ * cgroup_mutex, etc.
+ */
+struct mem_cgroup *mem_cgroup_from_obj(void *p)
+{
+	struct folio *folio;
+
+	if (mem_cgroup_disabled())
+		return NULL;
+
+	if (unlikely(is_vmalloc_addr(p)))
+		folio = page_folio(vmalloc_to_page(p));
+	else
+		folio = virt_to_folio(p);
+
+	return mem_cgroup_from_obj_folio(folio, p);
+}
+
+/*
+ * Returns a pointer to the memory cgroup to which the kernel object is charged.
+ * Similar to mem_cgroup_from_obj(), but faster and not suitable for objects,
+ * allocated using vmalloc().
+ *
+ * A passed kernel object must be a slab object or a generic kernel page.
+ *
+ * The caller must ensure the memcg lifetime, e.g. by taking rcu_read_lock(),
+ * cgroup_mutex, etc.
+ */
+struct mem_cgroup *mem_cgroup_from_slab_obj(void *p)
+{
+	if (mem_cgroup_disabled())
+		return NULL;
+
+	return mem_cgroup_from_obj_folio(virt_to_folio(p), p);
+}
+
 static struct obj_cgroup *__get_obj_cgroup_from_memcg(struct mem_cgroup *memcg)
 {
 	struct obj_cgroup *objcg = NULL;
-- 
2.35.3