On Thursday, October 20, 2016, Dan Carpenter &lt;<a href="mailto:dan.carpenter@oracle.com">dan.carpenter@oracle.com</a>&gt; wrote: &gt; Hello Jinshan Xiong, &gt; &gt; The patch 1e1db2a97be5: &quot;staging: lustre: clio: Revise read ahead &gt; implementation&quot; from Oct 2, 2016, leads to the following static &gt; checker warning: &gt; &gt;         drivers/staging/lustre/lustre/lov/lov_io.c:611 lov_io_read_ahead() &gt;         error: &#39;sub&#39; dereferencing possible ERR_PTR() &gt; &gt; drivers/staging/lustre/lustre/lov/lov_io.c &gt;    589  static int lov_io_read_ahead(const struct lu_env *env, &gt;    590                               const struct cl_io_slice *ios, &gt;    591                               pgoff_t start, struct cl_read_ahead *ra) &gt;    592  { &gt;    593          struct lov_io *lio = cl2lov_io(env, ios); &gt;    594          struct lov_object *loo = lio-&gt;lis_object; &gt;    595          struct cl_object *obj = lov2cl(loo); &gt;    596          struct lov_layout_raid0 *r0 = lov_r0(loo); &gt;    597          unsigned int pps; /* pages per stripe */ &gt;    598          struct lov_io_sub *sub; &gt;    599          pgoff_t ra_end; &gt;    600          loff_t suboff; &gt;    601          int stripe; &gt;    602          int rc; &gt;    603 &gt;    604          stripe = lov_stripe_number(loo-&gt;lo_lsm, cl_offset(obj, start)); &gt;    605          if (unlikely(!r0-&gt;lo_sub[stripe])) &gt;    606                  return -EIO; &gt;    607 &gt;    608          sub = lov_sub_get(env, lio, stripe); &gt;                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Hey Dan, May I ask what static checker are you using?