linux-kernel - Re: [4.7+] various memory corruption reports.

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Date:	Mon, 1 Aug 2016 14:03:15 +0300
From:	Andrey Ryabinin <ryabinin.a.a@...il.com>
To:	Dave Jones <davej@...emonkey.org.uk>,
	Linux Kernel <linux-kernel@...r.kernel.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>
Subject: Re: [4.7+] various memory corruption reports.

On 07/29/2016 09:39 PM, Dave Jones wrote:
> On Fri, Jul 29, 2016 at 08:56:08PM +0300, Andrey Ryabinin wrote:
> 
>  > >>  > I suspect this is false positives due to changes in KASAN.
>  > >>  > Bisection probably will point to
>  > >>  > 80a9201a5965f4715d5c09790862e0df84ce0614 ("mm, kasan: switch SLUB to
>  > >>  > stackdepot, enable memory quarantine for SLUB)"
>  > >>
>  > >> good call. reverting that changeset seems to have solved it.
>  > > Could you please try with this?
>  > Actually, this is not quite right, it should be like this:
> 
> 
> Seems to have stopped the corruption, but now I get NMi watchdog traces..
> 
> 

This should help:

---
 mm/kasan/kasan.c      | 4 ++--
 mm/kasan/quarantine.c | 8 ++++++--
 2 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/mm/kasan/kasan.c b/mm/kasan/kasan.c
index 3019cec..c99ef40 100644
--- a/mm/kasan/kasan.c
+++ b/mm/kasan/kasan.c
@@ -565,7 +565,7 @@ void kasan_kmalloc(struct kmem_cache *cache, const void *object, size_t size,
 	unsigned long redzone_start;
 	unsigned long redzone_end;
 
-	if (flags & __GFP_RECLAIM)
+	if (gfpflags_allow_blocking(flags))
 		quarantine_reduce();
 
 	if (unlikely(object == NULL))
@@ -596,7 +596,7 @@ void kasan_kmalloc_large(const void *ptr, size_t size, gfp_t flags)
 	unsigned long redzone_start;
 	unsigned long redzone_end;
 
-	if (flags & __GFP_RECLAIM)
+	if (gfpflags_allow_blocking(flags))
 		quarantine_reduce();
 
 	if (unlikely(ptr == NULL))
diff --git a/mm/kasan/quarantine.c b/mm/kasan/quarantine.c
index 65793f1..4852625 100644
--- a/mm/kasan/quarantine.c
+++ b/mm/kasan/quarantine.c
@@ -147,10 +147,14 @@ static void qlink_free(struct qlist_node *qlink, struct kmem_cache *cache)
 	struct kasan_alloc_meta *alloc_info = get_alloc_info(cache, object);
 	unsigned long flags;
 
-	local_irq_save(flags);
+	if (IS_ENABLED(CONFIG_SLAB))
+		local_irq_save(flags);
+
 	alloc_info->state = KASAN_STATE_FREE;
 	___cache_free(cache, object, _THIS_IP_);
-	local_irq_restore(flags);
+
+	if (IS_ENABLED(CONFIG_SLAB))
+		local_irq_restore(flags);
 }
 
 static void qlist_free_all(struct qlist_head *q, struct kmem_cache *cache)
-- 
2.7.3