On Tue, Oct 04, 2016 at 12:21:28PM -0400, CAI Qian wrote:
>
> > Not enough information, unfortunately (descriptor in question opened
> > outside of that log, sendfile(out_fd=578, in_fd=578, offset=0x7f8318a07000,
> > count=0x3ffc00) doesn't tell what *offset was before the call) ;-/
> >
> > Anyway, I've found and fixed a bug in pipe_advance(), which might or might
> > not help with those. Could you try vfs.git#work.splice_read (or #for-next)
> > and see if these persist?
> I am afraid that this can also reproduced in the latest #for-next . The warning
> always showed up at the end of trinity run. I captured more information this time.
OK, let's try to get more information about what's going on (this is on top
of either for-next or work.splice_read):
diff --git a/lib/iov_iter.c b/lib/iov_iter.c
index c97d661..a9cb9ff 100644
--- a/lib/iov_iter.c
+++ b/lib/iov_iter.c
@@ -313,6 +313,15 @@ static bool sanity(const struct iov_iter *i)
}
return true;
Bad:
+ printk(KERN_ERR "idx = %d, offset = %zd\n", i->idx, i->iov_offset);
+ printk(KERN_ERR "curbuf = %d, nrbufs = %d, buffers = %d\n",
+ pipe->curbuf, pipe->nrbufs, pipe->buffers);
+ for (idx = 0; idx < pipe->buffers; idx++)
+ printk(KERN_ERR "[%p %p %d %d]\n",
+ pipe->bufs[idx].ops,
+ pipe->bufs[idx].page,
+ pipe->bufs[idx].offset,
+ pipe->bufs[idx].len);
WARN_ON(1);
return false;
}
@@ -339,8 +348,11 @@ static size_t copy_page_to_iter_pipe(struct page *page, size_t offset, size_t by
if (unlikely(!bytes))
return 0;
- if (!sanity(i))
+ if (!sanity(i)) {
+ printk(KERN_ERR "page = %p, offset = %zd, size = %zd\n",
+ page, offset, bytes);
return 0;
+ }
off = i->iov_offset;
idx = i->idx;
@@ -518,6 +530,8 @@ static size_t copy_pipe_to_iter(const void *addr, size_t bytes,
addr += chunk;
}
i->count -= bytes;
+ if (!sanity(i))
+ printk(KERN_ERR "buggered after copy_to_iter\n");
return bytes;
}
@@ -629,6 +643,8 @@ static size_t pipe_zero(size_t bytes, struct iov_iter *i)
n -= chunk;
}
i->count -= bytes;
+ if (!sanity(i))
+ printk(KERN_ERR "buggered after zero_iter\n");
return bytes;
}
@@ -673,6 +689,8 @@ static void pipe_advance(struct iov_iter *i, size_t size)
struct pipe_buffer *buf;
int idx = i->idx;
size_t off = i->iov_offset;
+ struct iov_iter orig = *i;
+ size_t orig_size = size;
if (unlikely(i->count < size))
size = i->count;
@@ -702,6 +720,9 @@ static void pipe_advance(struct iov_iter *i, size_t size)
pipe->nrbufs--;
}
}
+ if (!sanity(i))
+ printk(KERN_ERR "buggered pipe_advance by %zd from [%d.%zd]",
+ orig_size, orig.idx, orig.iov_offset);
}
void iov_iter_advance(struct iov_iter *i, size_t size)
--
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