3.16.7-ckt2 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Paul Mackerras <paulus@xxxxxxxxx> commit ad0eab9293485d1c06237e9249f6d4dfa3d93d4d upstream. The branches of the if (i->type & ITER_BVEC) statement in iov_iter_single_seg_count() are the wrong way around; if ITER_BVEC is clear then we use i->bvec, when we should be using i->iov. This fixes it. In my case, the symptom that this caused was that a KVM guest doing filesystem operations on a virtual disk would result in one of qemu's threads on the host going into an infinite loop in generic_perform_write(). The loop would hit the copied == 0 case and call iov_iter_single_seg_count() to reduce the number of bytes to try to process, but because of the error, iov_iter_single_seg_count() would just return i->count and the loop made no progress and continued forever. Signed-off-by: Paul Mackerras <paulus@xxxxxxxxx> Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx> Signed-off-by: Luis Henriques <luis.henriques@xxxxxxxxxxxxx> --- mm/iov_iter.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/mm/iov_iter.c b/mm/iov_iter.c index 9a09f2034fcc..141dcf796d28 100644 --- a/mm/iov_iter.c +++ b/mm/iov_iter.c @@ -699,9 +699,9 @@ size_t iov_iter_single_seg_count(const struct iov_iter *i) if (i->nr_segs == 1) return i->count; else if (i->type & ITER_BVEC) - return min(i->count, i->iov->iov_len - i->iov_offset); - else return min(i->count, i->bvec->bv_len - i->iov_offset); + else + return min(i->count, i->iov->iov_len - i->iov_offset); } EXPORT_SYMBOL(iov_iter_single_seg_count); -- 2.1.0 -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html