On Fri, Jan 13, 2017 at 07:23:51AM +0000, Alan J. Wylie wrote: > at 15:28 on Thu 12-Jan-2017 Linus Torvalds (torva...@linux-foundation.org) > wrote: > > > So assuming Al hasn't figured it out by the time you get back, can > > you try to send us the same strace for the working case? > > Full output at https://wylie.me.uk/tmp/strace1.txt > > 1735 splice(5, NULL, 1, NULL, 9223372036854775807, 0) = -1 EAGAIN (Resource > temporarily unavailable)
Lovely... So it was getting -EAGAIN all along. Just in case - could you try the delta below and see if it triggers? Simply to exclude the possibility that it *is* this call of splice() and the change has somehow buggered cleanup after the kernel_readv() failure... diff --git a/fs/splice.c b/fs/splice.c index 873d83104e79..1a2d1bc7f19e 100644 --- a/fs/splice.c +++ b/fs/splice.c @@ -393,6 +393,9 @@ 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; if (pipe->nrbufs == pipe->buffers) return -EAGAIN; @@ -445,6 +448,16 @@ static ssize_t default_file_splice_read(struct file *in, loff_t *ppos, put_page(pages[i]); kvfree(pages); 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); + } return res; }