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Date: Mon, 3 Oct 2016 16:32:19 -0400 (EDT)
From: CAI Qian <caiqian@redhat.com>
To: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
        Dave Chinner <david@fromorbit.com>,
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Subject: Re: [RFC][CFT] splice_read reworked
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----- Original Message -----
> From: "CAI Qian" <caiqian@redhat.com>
> To: "Al Viro" <viro@ZenIV.linux.org.uk>
> Cc: "Linus Torvalds" <torvalds@linux-foundation.org>, "Dave Chinner" <david@fromorbit.com>, "linux-xfs"
> <linux-xfs@vger.kernel.org>, "Jens Axboe" <axboe@kernel.dk>, "Nick Piggin" <npiggin@gmail.com>,
> linux-fsdevel@vger.kernel.org
> Sent: Monday, October 3, 2016 10:06:27 AM
> Subject: Re: [RFC][CFT] splice_read reworked
> 
> 
> 
> ----- Original Message -----
> > From: "Al Viro" <viro@ZenIV.linux.org.uk>
> > To: "CAI Qian" <caiqian@redhat.com>
> > Cc: "Linus Torvalds" <torvalds@linux-foundation.org>, "Dave Chinner"
> > <david@fromorbit.com>, "linux-xfs"
> > <linux-xfs@vger.kernel.org>, "Jens Axboe" <axboe@kernel.dk>, "Nick Piggin"
> > <npiggin@gmail.com>,
> > linux-fsdevel@vger.kernel.org
> > Sent: Sunday, October 2, 2016 9:42:18 PM
> > Subject: Re: [RFC][CFT] splice_read reworked
> > 
> > On Fri, Sep 30, 2016 at 01:42:17PM -0400, CAI Qian wrote:
> > 
> > > [ 1599.151286] ------------[ cut here ]------------
> > > [ 1599.156457] WARNING: CPU: 37 PID: 95143 at lib/iov_iter.c:316
> > > sanity+0x75/0x80
> > 
> > [snip]
> > 
> > > [ 1599.344171]  [<ffffffff813e9b45>] sanity+0x75/0x80
> > > [ 1599.349518]  [<ffffffff813ec739>] copy_page_to_iter+0xf9/0x1e0
> > > [ 1599.356027]  [<ffffffff8120691f>] shmem_file_read_iter+0x9f/0x340
> > > [ 1599.362829]  [<ffffffff812bbeb9>] generic_file_splice_read+0xb9/0x1b0
> > > [ 1599.370015]  [<ffffffff812bc206>] do_splice_to+0x76/0x90
> > > [ 1599.375941]  [<ffffffff812bc2db>] splice_direct_to_actor+0xbb/0x220
> > > [ 1599.382935]  [<ffffffff812bba80>] ? generic_pipe_buf_nosteal+0x10/0x10
> > > [ 1599.390220]  [<ffffffff812bc4d8>] do_splice_direct+0x98/0xd0
> > > [ 1599.396537]  [<ffffffff81281dd1>] do_sendfile+0x1d1/0x3b0
> > > [ 1599.402563]  [<ffffffff81282973>] SyS_sendfile64+0x73/0xd0
> > > [ 1599.408685]  [<ffffffff81003f8c>] do_syscall_64+0x6c/0x1e0
> > > [ 1599.414820]  [<ffffffff817d927f>] entry_SYSCALL64_slow_path+0x25/0x25
> > 
> > IOW, sendfile from shmem...  How easily is that reproduced (IOW, did you
> > get any more of those)?
> > 
> It is pretty reproducible so far by just running the trinity from a docker
> container backed by overlayfs/xfs.
> 
> # su - test
> $ trinity
Also, AFACIT, this is NOT reproducible on v4.8 mainline, but only with this
splice_read reworked branch of vfs tree.
   CAI Qian