From: Al Viro <viro@ZenIV.linux.org.uk>
To: "Alan J. Wylie" <alan@wylie.me.uk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
Thorsten Leemhuis <regressions@leemhuis.info>,
linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: 4.9.0 regression in pipe-backed iov_iter with systemd-nspawn
Date: Fri, 13 Jan 2017 10:20:19 +0000 [thread overview]
Message-ID: <20170113102019.GK1555@ZenIV.linux.org.uk> (raw)
In-Reply-To: <22648.41914.351371.678606@wylie.me.uk>
On Fri, Jan 13, 2017 at 09:54:02AM +0000, Alan J. Wylie wrote:
> root 1669 0.0 0.0 76144 5412 ? S 09:51 0:00 \_ /usr/sbin/postdrop -r
>
> Another hang.
>
> # dmesg | tail
> [ 22.352442] r8169 0000:03:00.0: loading /lib/firmware/4.9.3-dirty/rtl_nic/rtl8168e-3.fw failed with error -2
> [ 22.408814] r8169 0000:03:00.0: direct-loading rtl_nic/rtl8168e-3.fw
> [ 22.408821] fw_set_page_data: fw-rtl_nic/rtl8168e-3.fw buf=ffff92b7b1cb8c80 data=ffffad1641179000 size=3872
> [ 22.536043] r8169 0000:03:00.0 enp3s0: link down
> [ 22.536079] r8169 0000:03:00.0 enp3s0: link down
> [ 24.873801] r8169 0000:03:00.0 enp3s0: link up
> [ 24.874766] br0: port 1(enp3s0) entered blocking state
> [ 24.876622] br0: port 1(enp3s0) entered forwarding state
> [ 24.878560] IPv6: ADDRCONF(NETDEV_CHANGE): br0: link becomes ready
> [ 219.683974] nr: 0->16, cur: 5->5, buffers: 16->16
OK, so it is iov_iter_advance() failing to free the shit allocated, either
due to some breakage in pipe_advance() or buggered 'copied'... Let's
see which one; could you apply the following and run your reproducer? The
only difference from the previous is that it collects and prints a bit more,
so it should be just as reproducible...
diff --git a/fs/splice.c b/fs/splice.c
index 873d83104e79..11477609e7f7 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -393,6 +393,10 @@ static ssize_t default_file_splice_read(struct file *in, loff_t *ppos,
size_t offset, dummy, copied = 0;
ssize_t res;
int i;
+ unsigned nrbufs = pipe->nrbufs,
+ curbuf = pipe->curbuf,
+ buffers = pipe->buffers;
+ int idx, count, offs;
if (pipe->nrbufs == pipe->buffers)
return -EAGAIN;
@@ -444,7 +448,22 @@ static ssize_t default_file_splice_read(struct file *in, loff_t *ppos,
for (i = 0; i < nr_pages; i++)
put_page(pages[i]);
kvfree(pages);
+ count = to.count;
+ idx = to.idx;
+ offs = to.iov_offset;
iov_iter_advance(&to, copied); /* truncates and discards */
+ if (res == -EAGAIN && (
+ pipe->nrbufs != nrbufs ||
+ pipe->curbuf != curbuf ||
+ pipe->buffers != buffers)
+ ) {
+ printk(KERN_ERR "nr: %d->%d, cur: %d->%d, buffers: %d->%d\n",
+ nrbufs, pipe->nrbufs,
+ curbuf, pipe->curbuf,
+ buffers, pipe->buffers);
+ printk(KERN_ERR "copied: %zd, count:%d, idx:%d, offs:%d\n",
+ copied, count, idx, offs);
+ }
return res;
}
next prev parent reply other threads:[~2017-01-13 10:20 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-01-12 20:26 4.9.0 regression in pipe-backed iov_iter with systemd-nspawn Alan J. Wylie
2017-01-12 20:31 ` Al Viro
2017-01-12 20:38 ` Alan J. Wylie
2017-01-12 22:26 ` Linus Torvalds
2017-01-12 22:37 ` Al Viro
2017-01-12 22:46 ` Al Viro
2017-01-12 23:02 ` Linus Torvalds
2017-01-12 23:14 ` Al Viro
2017-01-12 23:14 ` Linus Torvalds
2017-01-12 23:27 ` Al Viro
2017-01-12 22:46 ` Alan J. Wylie
2017-01-12 22:58 ` Al Viro
2017-01-12 23:28 ` Linus Torvalds
2017-01-13 4:00 ` Al Viro
2017-01-13 7:38 ` Alan J. Wylie
2017-01-13 7:23 ` Alan J. Wylie
2017-01-13 9:33 ` Al Viro
2017-01-13 9:54 ` Alan J. Wylie
2017-01-13 10:20 ` Al Viro [this message]
2017-01-13 10:32 ` Alan J. Wylie
2017-01-13 11:25 ` Al Viro
2017-01-13 11:18 ` Al Viro
2017-01-13 19:33 ` Linus Torvalds
2017-01-13 20:08 ` Al Viro
2017-01-13 20:11 ` Al Viro
2017-01-13 20:32 ` Linus Torvalds
2017-01-13 20:47 ` Al Viro
2017-01-13 21:55 ` Al Viro
2017-01-13 21:59 ` Al Viro
2017-01-13 22:13 ` Al Viro
2017-01-13 22:50 ` Al Viro
2017-01-14 0:59 ` Linus Torvalds
2017-01-14 1:24 ` Al Viro
2017-01-14 1:43 ` Al Viro
2017-01-14 1:46 ` Linus Torvalds
2017-01-14 1:57 ` Al Viro
2017-01-15 0:53 ` Al Viro
2017-01-14 13:16 ` Alan J. Wylie
2017-01-14 16:29 ` Alan J. Wylie
2017-01-14 17:57 ` Linus Torvalds
2017-01-13 20:08 ` Linus Torvalds
2017-01-13 20:16 ` Al Viro
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