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[173.66.96.194]) by smtp.googlemail.com with ESMTPSA id u7sm4206413qkh.2.2017.01.11.06.37.06 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Wed, 11 Jan 2017 06:37:06 -0800 (PST) Message-ID: <1484145426.1643.7.camel@gmail.com> Subject: Re: net/atm: warning in alloc_tx/__might_sleep From: Chas Williams <3chas3@gmail.com> To: Andrey Konovalov , "David S. Miller" , Alexey Kuznetsov , James Morris , Hideaki YOSHIFUJI , Patrick McHardy , netdev , LKML , Al Viro Cc: Dmitry Vyukov , Kostya Serebryany , Eric Dumazet , syzkaller Date: Wed, 11 Jan 2017 09:37:06 -0500 In-Reply-To: References: X-Mailer: Evolution 3.20.5 (3.20.5-1.fc24) Mime-Version: 1.0 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Mon, 2017-01-09 at 18:20 +0100, Andrey Konovalov wrote: > Hi! > > I've got the following error report while running the syzkaller fuzzer. > > On commit a121103c922847ba5010819a3f250f1f7fc84ab8 (4.10-rc3). > > A reproducer is attached. > > ------------[ cut here ]------------ > WARNING: CPU: 0 PID: 4114 at kernel/sched/core.c:7737 __might_sleep+0x149/0x1a0 > do not call blocking ops when !TASK_RUNNING; state=1 set at > [] prepare_to_wait+0x182/0x530 > Modules linked in: > CPU: 0 PID: 4114 Comm: a.out Not tainted 4.10.0-rc3+ #59 > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 > Call Trace: > __dump_stack lib/dump_stack.c:15 > dump_stack+0x292/0x398 lib/dump_stack.c:51 > __warn+0x19f/0x1e0 kernel/panic.c:547 > warn_slowpath_fmt+0xc5/0x110 kernel/panic.c:562 > __might_sleep+0x149/0x1a0 kernel/sched/core.c:7732 > slab_pre_alloc_hook mm/slab.h:408 > slab_alloc_node mm/slub.c:2634 > kmem_cache_alloc_node+0x14a/0x280 mm/slub.c:2744 > __alloc_skb+0x10f/0x800 net/core/skbuff.c:219 > alloc_skb ./include/linux/skbuff.h:926 > alloc_tx net/atm/common.c:75 This is likely alloc_skb(..., GFP_KERNEL) in alloc_tx(). The simplest fix for this would be simply to switch this GFP_ATOMIC. See if this is any better. diff --git a/net/atm/common.c b/net/atm/common.c index a3ca922..d84220c 100644 --- a/net/atm/common.c +++ b/net/atm/common.c @@ -72,7 +72,7 @@ static struct sk_buff *alloc_tx(struct atm_vcc *vcc, unsigned int size) sk_wmem_alloc_get(sk), size, sk->sk_sndbuf); return NULL; } - while (!(skb = alloc_skb(size, GFP_KERNEL))) + while (!(skb = alloc_skb(size, GFP_ATOMIC))) schedule(); pr_debug("%d += %d\n", sk_wmem_alloc_get(sk), skb->truesize); atomic_add(skb->truesize, &sk->sk_wmem_alloc);