On Sat, Nov 14, 2020 at 05:50:48AM +0000, Al Viro wrote:
> On Fri, Nov 13, 2020 at 09:14:20PM -0700, Nathan Chancellor wrote:
> 
> > Unfortunately that patch does not solve my issue. Is there any other
> > debugging I should add?
> 
> Hmm...  I wonder which file it is; how about
> 		if (WARN_ON(!iovec.iov_len))
> 			printk(KERN_ERR "odd readv on %pd4\n", file);
> in the loop in fs/read_write.c:do_loop_readv_writev()?

Assuming you mean this?

diff --git a/fs/read_write.c b/fs/read_write.c
index 75f764b43418..91dc07074a3f 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -757,6 +757,9 @@ static ssize_t do_loop_readv_writev(struct file *filp, struct iov_iter *iter,
 		struct iovec iovec = iov_iter_iovec(iter);
 		ssize_t nr;
 
+		if (WARN_ON(!iovec.iov_len))
+			printk(KERN_ERR "odd readv on %pd4\n", filp);
+
 		if (type == READ) {
 			nr = filp->f_op->read(filp, iovec.iov_base,
 					      iovec.iov_len, ppos);

---

Assuming so, I have attached the output both with and without the
WARN_ON. Looks like mountinfo is what is causing the error?

Cheers,
Nathan