At Mon, 5 Jan 2015 21:46:34 -0500,
Dave Jones wrote:
>
> On Mon, Jan 05, 2015 at 05:46:15PM -0800, Linus Torvalds wrote:
> > It's a day delayed - not because of any particular development issues,
> > but simply because I was tiling a bathroom yesterday. But rc3 is out
> > there now, and things have stayed reasonably calm. I really hope that
> > implies that 3.19 is looking good, but it's equally likely that it's
> > just that people are still recovering from the holiday season.
> >
> > A bit over three quarters of the changes here are drivers - mostly
> > networking, thermal, input layer, sound, power management. The rest is
> > misc - filesystems, core networking, some arch fixes, etc. But all of
> > it is pretty small.
> >
> > So go out and test,
>
> This has been there since just before rc1. Is there a fix for this
> stalled in someones git tree maybe ?
>
> [ 7.952588] WARNING: CPU: 0 PID: 299 at kernel/sched/core.c:7303
> __might_sleep+0x8d/0xa0()
> [ 7.952592] do not call blocking ops when !TASK_RUNNING; state=1 set at
> [<ffffffff910a0f7a>] prepare_to_wait+0x2a/0x90
> [ 7.952595] CPU: 0 PID: 299 Comm: systemd-readahe Not tainted 3.19.0-rc3+
> #100
> [ 7.952597] 0000000000001c87 00000000720a2c76 ffff8800b2513c88
> ffffffff915b47c7
> [ 7.952598] ffffffff910a3648 ffff8800b2513ce0 ffff8800b2513cc8
> ffffffff91062c30
> [ 7.952599] 0000000000000000 ffffffff91796fb2 000000000000026d
> 0000000000000000
> [ 7.952600] Call Trace:
> [ 7.952603] [<ffffffff915b47c7>] dump_stack+0x4c/0x65
> [ 7.952604] [<ffffffff910a3648>] ? down_trylock+0x28/0x40
> [ 7.952606] [<ffffffff91062c30>] warn_slowpath_common+0x80/0xc0
> [ 7.952607] [<ffffffff91062cc0>] warn_slowpath_fmt+0x50/0x70
> [ 7.952608] [<ffffffff910a0f7a>] ? prepare_to_wait+0x2a/0x90
> [ 7.952610] [<ffffffff910a0f7a>] ? prepare_to_wait+0x2a/0x90
> [ 7.952611] [<ffffffff910867ed>] __might_sleep+0x8d/0xa0
> [ 7.952614] [<ffffffff915b8ea9>] mutex_lock_nested+0x39/0x3e0
> [ 7.952616] [<ffffffff910a77ad>] ? trace_hardirqs_on+0xd/0x10
> [ 7.952617] [<ffffffff910a0fac>] ? prepare_to_wait+0x5c/0x90
> [ 7.952620] [<ffffffff911a63e0>] fanotify_read+0xe0/0x5b0
> [ 7.952622] [<ffffffff91090801>] ? sched_clock_cpu+0xc1/0xd0
> [ 7.952624] [<ffffffff91242459>] ? selinux_file_permission+0xb9/0x130
> [ 7.952626] [<ffffffff910a14d0>] ? prepare_to_wait_event+0xf0/0xf0
> [ 7.952628] [<ffffffff91162513>] __vfs_read+0x13/0x50
> [ 7.952629] [<ffffffff911625d8>] vfs_read+0x88/0x140
> [ 7.952631] [<ffffffff911626e7>] SyS_read+0x57/0xd0
> [ 7.952633] [<ffffffff915bd952>] system_call_fastpath+0x12/0x17
Just "me too" (but overlooked until recently).
The cause is a mutex_lock() call right after prepare_to_wait() with
TASK_INTERRUPTIBLE in fanotify_read().
static ssize_t fanotify_read(struct file *file, char __user *buf,
size_t count, loff_t *pos)
{
....
while (1) {
prepare_to_wait(&group->notification_waitq, &wait,
TASK_INTERRUPTIBLE);
mutex_lock(&group->notification_mutex);
I saw Peter already fixed a similar code in inotify_user.c by commit
e23738a7300a (but interestingly for a different reason, "Deal with
nested sleeps"). Supposedly a similar fix would be needed for
fanotify_user.c.
Eric, any fixes planned?
thanks,
Takashi
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