[Devel] [PATCH RHEL7 COMMIT] mm/kasan: get rid of ->alloc_size in struct kasan_alloc_meta

[Konstantin Khorenko]

The commit is pushed to "branch-rh7-3.10.0-693.1.1.vz7.37.x-ovz" and will appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh7-3.10.0-693.1.1.vz7.37.4
------>
commit fd7007a2bbc40efcb7f219ba14f39a8ef7d0db11
Author: Andrey Ryabinin <aryabinin at virtuozzo.com>
Date:   Fri Sep 15 17:27:26 2017 +0300

    mm/kasan: get rid of ->alloc_size in struct kasan_alloc_meta
    
    Size of slab object already stored in cache->object_size.
    
    Note, that kmalloc() internally rounds up size of allocation, so
    object_size may be not equal to alloc_size, but, usually we don't need
    to know the exact size of allocated object.  In case if we need that
    information, we still can figure it out from the report.  The dump of
    shadow memory allows to identify the end of allocated memory, and
    thereby the exact allocation size.
    
    Link: http://lkml.kernel.org/r/1470062715-14077-4-git-send-email-aryabinin@virtuozzo.com
    Signed-off-by: Andrey Ryabinin <aryabinin at virtuozzo.com>
    
    Cc: Alexander Potapenko <glider at google.com>
    Cc: Dmitry Vyukov <dvyukov at google.com>
    Signed-off-by: Andrew Morton <akpm at linux-foundation.org>
    Signed-off-by: Linus Torvalds <torvalds at linux-foundation.org>
    
    https://jira.sw.ru/browse/PSBM-69081
    (cherry picked from commit 47b5c2a0f021e90a79845d1a1353780e5edd0bce)
    Signed-off-by: Andrey Ryabinin <aryabinin at virtuozzo.com>
---
 mm/kasan/kasan.c  | 1 -
 mm/kasan/kasan.h  | 4 +---
 mm/kasan/report.c | 8 +++-----
 3 files changed, 4 insertions(+), 9 deletions(-)

diff --git a/mm/kasan/kasan.c b/mm/kasan/kasan.c
index d7c8143..a8d3e08 100644
--- a/mm/kasan/kasan.c
+++ b/mm/kasan/kasan.c
@@ -545,7 +545,6 @@ void kasan_kmalloc(struct kmem_cache *cache, const void *object, size_t size,
 			get_alloc_info(cache, object);
 
 		alloc_info->state = KASAN_STATE_ALLOC;
-		alloc_info->alloc_size = size;
 		set_track(&alloc_info->track, flags);
 	}
 }
diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
index 1143e64b..1175fa0 100644
--- a/mm/kasan/kasan.h
+++ b/mm/kasan/kasan.h
@@ -76,9 +76,7 @@ struct kasan_track {
 
 struct kasan_alloc_meta {
 	struct kasan_track track;
-	u32 state : 2;	/* enum kasan_state */
-	u32 alloc_size : 30;
-	u32 reserved;
+	u32 state;
 };
 
 struct qlist_node {
diff --git a/mm/kasan/report.c b/mm/kasan/report.c
index ef85919..45f1762 100644
--- a/mm/kasan/report.c
+++ b/mm/kasan/report.c
@@ -118,7 +118,9 @@ static void kasan_object_err(struct kmem_cache *cache, struct page *page,
 	struct kasan_free_meta *free_info;
 
 	dump_stack();
-	pr_err("Object at %p, in cache %s\n", object, cache->name);
+	pr_err("Object at %p, in cache %s size: %d\n", object, cache->name,
+		cache->object_size);
+
 	if (!(cache->flags & SLAB_KASAN))
 		return;
 	switch (alloc_info->state) {
@@ -126,15 +128,11 @@ static void kasan_object_err(struct kmem_cache *cache, struct page *page,
 		pr_err("Object not allocated yet\n");
 		break;
 	case KASAN_STATE_ALLOC:
-		pr_err("Object allocated with size %u bytes.\n",
-		       alloc_info->alloc_size);
 		pr_err("Allocation:\n");
 		print_track(&alloc_info->track);
 		break;
 	case KASAN_STATE_FREE:
 	case KASAN_STATE_QUARANTINE:
-		pr_err("Object freed, allocated with size %u bytes\n",
-		       alloc_info->alloc_size);
 		free_info = get_free_info(cache, object);
 		pr_err("Allocation:\n");
 		print_track(&alloc_info->track);