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Date: Wed, 2 Sep 2015 16:11:13 -0700
From: Greg KH <gregkh@linuxfoundation.org>
To: Andy Grover <agrover@redhat.com>
Cc: hjk@hansjkoch.de, linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: __might_sleep in uio_read()?
Message-ID: <20150902231113.GA11383@kroah.com>
References: <55E77BF6.9000109@redhat.com>
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On Wed, Sep 02, 2015 at 03:45:10PM -0700, Andy Grover wrote:
> Hi Hans and Greg,
> 
> Is this an issue with uio? I swear it didn't used to throw this warning...
> 
> Thanks -- Andy
> 
> [ 5174.883261] ------------[ cut here ]------------
> [ 5174.883617] WARNING: CPU: 0 PID: 1532 at
> /home/agrover/git/kernel/kernel/sched/core.c:7389 __might_sleep+0x7d/0x90()
> [ 5174.884407] do not call blocking ops when !TASK_RUNNING; state=1 set at
> [<ffffffffa02a5821>] uio_read+0x91/0x170 [uio]
> [ 5174.885198] Modules linked in: tcm_loop target_core_user uio
> target_core_pscsi target_core_file target_core_iblock iscsi_target_mod
> target_core_mod uinput fuse nfsv3 nfs_acl nfs lockd grace fscache sunrpc
> microcode i2c_piix4 virtio_balloon i2c_core xfs libcrc32c crc32c_intel
> virtio_net virtio_blk
> [ 5174.887351] CPU: 0 PID: 1532 Comm: tcmu-runner Not tainted 4.2.0-rc7+
> #178
> [ 5174.887853] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
> 1.8.1-20150318_183358- 04/01/2014
> [ 5174.888633]  ffffffff81a3b870 ffff880045393ca8 ffffffff817afaae
> 0000000000000000
> [ 5174.889224]  ffff880045393cf8 ffff880045393ce8 ffffffff8109a846
> ffff880045393cd8
> [ 5174.889793]  ffffffffa02a7150 00000000000002dc 0000000000000000
> ffff880045008000
> [ 5174.890375] Call Trace:
> [ 5174.890562]  [<ffffffff817afaae>] dump_stack+0x4c/0x65
> [ 5174.890938]  [<ffffffff8109a846>] warn_slowpath_common+0x86/0xc0
> [ 5174.891388]  [<ffffffff8109a8c6>] warn_slowpath_fmt+0x46/0x50
> [ 5174.891808]  [<ffffffffa02a5821>] ? uio_read+0x91/0x170 [uio]
> [ 5174.892237]  [<ffffffffa02a5821>] ? uio_read+0x91/0x170 [uio]
> [ 5174.892653]  [<ffffffff810c584d>] __might_sleep+0x7d/0x90
> [ 5174.893055]  [<ffffffff811ea023>] __might_fault+0x43/0xa0
> [ 5174.893448]  [<ffffffff817b31ce>] ? schedule+0x3e/0x90
> [ 5174.893820]  [<ffffffffa02a58c2>] uio_read+0x132/0x170 [uio]
> [ 5174.894240]  [<ffffffff810cbb80>] ? wake_up_q+0x70/0x70
> [ 5174.894620]  [<ffffffff81236168>] __vfs_read+0x28/0xe0
> [ 5174.894993]  [<ffffffff81353233>] ? security_file_permission+0xa3/0xc0
> [ 5174.895541]  [<ffffffff8123678f>] ? rw_verify_area+0x4f/0xf0
> [ 5174.896006]  [<ffffffff812368ba>] vfs_read+0x8a/0x140
> [ 5174.896391]  [<ffffffff817b28f5>] ? __schedule+0x425/0xcc0
> [ 5174.896788]  [<ffffffff812375d9>] SyS_read+0x49/0xb0
> [ 5174.897160]  [<ffffffff817b9bee>] entry_SYSCALL_64_fastpath+0x12/0x76
> [ 5174.897625] ---[ end trace 61765cb39fe48dd5 ]---

I don't think anything has changed here in a while, any chance you can
bisect this?

And what uio driver are you using?

thanks,

greg k-h