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

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Date:	Fri, 29 Jul 2016 20:32:41 +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 06:49 PM, Dave Jones wrote:
> On Fri, Jul 29, 2016 at 06:21:12PM +0300, Andrey Ryabinin wrote:
>  > 2016-07-29 18:19 GMT+03:00 Dave Jones <davej@...emonkey.org.uk>:
>  > > On Fri, Jul 29, 2016 at 11:05:14AM -0400, Dave Jones wrote:
>  > >  > I've just gotten back into running trinity on daily pulls of master, and it seems pretty horrific
>  > >  > right now.  I can reproduce some kind of memory corruption within a couple minutes runtime.
>  > >  >
>  > >  > ,,,
>  > >  >
>  > >  > I'll work on narrowing down the exact syscalls needed to trigger this.
>  > >
>  > > Even limiting it to do just a simple syscall like execve (which fails most the time in trinity)
>  > > triggers it, suggesting it's not syscall related, but the fact that trinity is forking/killing
>  > > tons of processes at high rate is stressing something more fundamental.
>  > >
>  > > Given how easy this reproduces, I'll see if bisecting gives up something useful.
>  > 
>  > 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.
> 

Unfortunately, I wasn't able to reproduce it.

Could you please try with this?

---
 mm/kasan/kasan.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/kasan/kasan.c b/mm/kasan/kasan.c
index b6f99e8..bf25340 100644
--- a/mm/kasan/kasan.c
+++ b/mm/kasan/kasan.c
@@ -543,8 +543,8 @@ bool kasan_slab_free(struct kmem_cache *cache, void *object)
 		switch (alloc_info->state) {
 		case KASAN_STATE_ALLOC:
 			alloc_info->state = KASAN_STATE_QUARANTINE;
-			quarantine_put(free_info, cache);
 			set_track(&free_info->track, GFP_NOWAIT);
+			quarantine_put(free_info, cache);
 			kasan_poison_slab_free(cache, object);
 			return true;
 		case KASAN_STATE_QUARANTINE:
-- 
2.7.3