Re: net/atm: vcc_sendmsg calls kmem_cache_alloc in non-blocking context

[Eric Dumazet]

On Tue, Feb 28, 2017 at 7:26 AM, Dmitry Vyukov <dvyukov@xxxxxxxxxx> wrote:
> Hello,
>
> I've got the following WARNING while running syzkaller fuzzer:
>
> ------------[ cut here ]------------
> WARNING: CPU: 0 PID: 9197 at kernel/sched/core.c:6149
> __might_sleep+0x149/0x1a0 kernel/sched/core.c:6144
> do not call blocking ops when !TASK_RUNNING; state=1 set at
> [<ffffffff813fa422>] prepare_to_wait+0x182/0x530
> kernel/sched/wait.c:178
> Kernel panic - not syncing: panic_on_warn set ...
>
> CPU: 0 PID: 9197 Comm: syz-executor2 Not tainted 4.10.0+ #54
> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
> Call Trace:
>  __dump_stack lib/dump_stack.c:15 [inline]
>  dump_stack+0x292/0x398 lib/dump_stack.c:51
>  panic+0x1cb/0x3a9 kernel/panic.c:179
>  __warn+0x1c4/0x1e0 kernel/panic.c:540
>  warn_slowpath_fmt+0xc5/0x110 kernel/panic.c:563
>  __might_sleep+0x149/0x1a0 kernel/sched/core.c:6144
>  slab_pre_alloc_hook mm/slab.h:432 [inline]
>  slab_alloc_node mm/slub.c:2644 [inline]
>  kmem_cache_alloc_node+0x14a/0x280 mm/slub.c:2754
>  __alloc_skb+0x10f/0x770 net/core/skbuff.c:219
>  alloc_skb include/linux/skbuff.h:932 [inline]
>  alloc_tx net/atm/common.c:75 [inline]
>  vcc_sendmsg+0x5e8/0x1010 net/atm/common.c:609
>  sock_sendmsg_nosec net/socket.c:633 [inline]
>  sock_sendmsg+0xca/0x110 net/socket.c:643
>  ___sys_sendmsg+0x9d2/0xae0 net/socket.c:1985
>  __sys_sendmsg+0x138/0x320 net/socket.c:2019
>  SYSC_sendmsg net/socket.c:2030 [inline]
>  SyS_sendmsg+0x2d/0x50 net/socket.c:2026
>  entry_SYSCALL_64_fastpath+0x1f/0xc2
> RIP: 0033:0x4458b9
> RSP: 002b:00007f20dd37ab58 EFLAGS: 00000286 ORIG_RAX: 000000000000002e
> RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 00000000004458b9
> RDX: 0000000000000000 RSI: 0000000020000000 RDI: 0000000000000005
> RBP: 00000000006e1af0 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000286 R12: 0000000000708000
> R13: 0000000000000005 R14: 0000000020000ff8 R15: 0000000000000008
>
> On commit 86292b33d4b79ee03e2f43ea0381ef85f077c760

Looks the typical pattern for which Cong sent various patches.

like "inet: fix sleeping inside inet_wait_for_connect()"