From: Al Viro <viro@ZenIV.linux.org.uk>
To: Dave Jones <davej@codemonkey.org.uk>, Chris Mason <clm@fb.com>,
Josef Bacik <jbacik@fb.com>, David Sterba <dsterba@suse.com>,
linux-btrfs@vger.kernel.org,
Linux Kernel <linux-kernel@vger.kernel.org>
Subject: Re: btrfs_direct_IO oops
Date: Mon, 10 Oct 2016 04:43:57 +0100 [thread overview]
Message-ID: <20161010034356.GY19539@ZenIV.linux.org.uk> (raw)
In-Reply-To: <20161009151106.damzuhyjpdzq4x2w@codemonkey.org.uk>
On Sun, Oct 09, 2016 at 11:11:06AM -0400, Dave Jones wrote:
> idx = 0, offset = 0
== starts at slot 0, nothing put into it yet, but
> curbuf = 0, nrbufs = 1, buffers = 16
> [ffffffff9fa21100 ffffea00065f6d80 0 4096]
the underlying pipe has something stored into slot 0. That definitely
should not happen.
> WARNING: CPU: 0 PID: 29610 at lib/iov_iter.c:327 sanity+0x102/0x150
> CPU: 0 PID: 29610 Comm: trinity-c9 Not tainted 4.8.0-think+ #8
> ffffc900007b7ae8
> ffffffff9f3e2011
> 0000000000000000
> 0000000000000000
> ffffffff9fc1e22b
> ffffffff9f3fa2f2
> ffffc900007b7b28
> ffffffff9f08b010
>
> 0000014734c3d60f
> ffffffff9fc1e22b
> 0000000000000147
> 0000000000000010
*blink*
where have those come from?
> Call Trace:
> [<ffffffff9f3e2011>] dump_stack+0x6c/0x9b
> [<ffffffff9f3fa2f2>] ? sanity+0x102/0x150
> [<ffffffff9f08b010>] __warn+0x110/0x130
> [<ffffffff9f08b19c>] warn_slowpath_null+0x2c/0x40
> [<ffffffff9f3fa2f2>] sanity+0x102/0x150
> [<ffffffff9f3fe62e>] copy_page_to_iter+0x2be/0x480
> [<ffffffff9f1932da>] ? pagecache_get_page+0xba/0x4f0
> [<ffffffff9f195b85>] generic_file_read_iter+0x245/0xd30
> [<ffffffff9f2764ed>] generic_file_splice_read+0xfd/0x230
> [<ffffffff9f2763f0>] ? pipe_to_user+0x40/0x40
> [<ffffffff9f275f08>] do_splice_to+0x98/0xd0
> [<ffffffff9f276014>] splice_direct_to_actor+0xd4/0x2c0
> [<ffffffff9f275660>] ? generic_pipe_buf_nosteal+0x10/0x10
> [<ffffffff9f2762c5>] do_splice_direct+0xc5/0x110
> [<ffffffff9f2381c2>] do_sendfile+0x242/0x470
> [<ffffffff9f23929d>] SyS_sendfile64+0x7d/0xf0
> [<ffffffff9f00279f>] do_syscall_64+0x7f/0x200
> [<ffffffff9f9de5cb>] entry_SYSCALL64_slow_path+0x25/0x25
> ---[ end trace 2c7bd411d4aa0491 ]---
Very interesting. Could you slap something like
diff --git a/lib/iov_iter.c b/lib/iov_iter.c
index 0ce3411..1ef00e7 100644
--- a/lib/iov_iter.c
+++ b/lib/iov_iter.c
@@ -682,8 +682,9 @@ static void pipe_advance(struct iov_iter *i, size_t size)
{
struct pipe_inode_info *pipe = i->pipe;
struct pipe_buffer *buf;
- int idx = i->idx;
- size_t off = i->iov_offset;
+ int old_idx = idx = i->idx;
+ size_t old_off = off = i->iov_offset;
+ size_t old_size = size;
if (unlikely(i->count < size))
size = i->count;
@@ -713,6 +714,9 @@ static void pipe_advance(struct iov_iter *i, size_t size)
pipe->nrbufs--;
}
}
+ if (!sanity(i))
+ printk(KERN_ERR "buggered pipe_advance(%zd) [%d,%zd]",
+ old_size, old_idx, old_off);
}
void iov_iter_advance(struct iov_iter *i, size_t size)
in there and try to reproduce that one?
next prev parent reply other threads:[~2016-10-10 3:44 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-10-08 18:08 btrfs_direct_IO oops Dave Jones
2016-10-08 18:29 ` Al Viro
2016-10-08 23:20 ` Dave Jones
2016-10-09 15:11 ` Dave Jones
2016-10-10 3:43 ` Al Viro [this message]
2016-10-10 13:11 ` Dave Jones
2016-10-10 15:55 ` Al Viro
2016-10-10 17:17 ` Dave Jones
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