tree: git://linux-nfs.org/~cel/cel-2.6.git nfsd-more-tracepoints head: e0f9a869d6aa51ecf380be437d5cb68b31ad48ac commit: 6393b2237f53af6f1d9ba87abb4d222d37653866 [30/34] NFSD: Add a lookup tracepoint config: x86_64-randconfig-s022-20200921 (attached as .config) compiler: gcc-9 (Debian 9.3.0-15) 9.3.0 reproduce: # apt-get install sparse # sparse version: v0.6.2-201-g24bdaac6-dirty git checkout 6393b2237f53af6f1d9ba87abb4d222d37653866 # save the attached .config to linux build tree make W=1 C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__' ARCH=x86_64 If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot <lkp(a)intel.com&gt; sparse warnings: (new ones prefixed by >>) git remote add cel-cel-2.6 git://linux-nfs.org/~cel/cel-2.6.git git fetch --no-tags cel-cel-2.6 nfsd-more-tracepoints git checkout 6393b2237f53af6f1d9ba87abb4d222d37653866 vim +109 fs/nfsd/vfs.c 51 52 /* 53 * Called from nfsd_lookup and encode_dirent. Check if we have crossed 54 * a mount point. 55 * Returns -EAGAIN or -ETIMEDOUT leaving *dpp and *expp unchanged, 56 * or nfs_ok having possibly changed *dpp and *expp 57 */ 58 int 59 nfsd_cross_mnt(struct svc_rqst *rqstp, struct dentry **dpp, 60 struct svc_export **expp) 61 { 62 struct svc_export *exp = *expp, *exp2 = NULL; 63 struct dentry *dentry = *dpp; 64 struct path path = {.mnt = mntget(exp->ex_path.mnt), 65 .dentry = dget(dentry)}; 66 int err = 0; 67 68 err = follow_down(&path); 69 if (err < 0) 70 goto out; 71 if (path.mnt == exp->ex_path.mnt && path.dentry == dentry && 72 nfsd_mountpoint(dentry, exp) == 2) { 73 /* This is only a mountpoint in some other namespace */ 74 path_put(&path); 75 goto out; 76 } 77 78 exp2 = rqst_exp_get_by_name(rqstp, &path); 79 if (IS_ERR(exp2)) { 80 err = PTR_ERR(exp2); 81 /* 82 * We normally allow NFS clients to continue 83 * "underneath" a mountpoint that is not exported. 84 * The exception is V4ROOT, where no traversal is ever 85 * allowed without an explicit export of the new 86 * directory. 87 */ 88 if (err == -ENOENT && !(exp->ex_flags & NFSEXP_V4ROOT)) 89 err = 0; 90 path_put(&path); 91 goto out; 92 } 93 if (nfsd_v4client(rqstp) || 94 (exp->ex_flags & NFSEXP_CROSSMOUNT) || EX_NOHIDE(exp2)) { 95 /* successfully crossed mount point */ 96 /* 97 * This is subtle: path.dentry is *not* on path.mnt 98 * at this point. The only reason we are safe is that 99 * original mnt is pinned down by exp, so we should 100 * put path *before* putting exp 101 */ 102 *dpp = path.dentry; 103 path.dentry = dentry; 104 *expp = exp2; 105 exp2 = exp; 106 } 107 path_put(&path); 108 exp_put(exp2); 111 be32_to_cpu(rqstp->rq_xid), be32_to_cpu(err)); 112 out: 113 return err; 114 } 115 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org