Hello, At the end of the function, if found is false then the inner list_for_each_entry has executed. Once that happens, the copy allocated at the beginning of the function is no longer visible. In particular, copy will be bound to the dummy element at the beginning/end of the list. julia ---------- Forwarded message ---------- Date: Tue, 20 Nov 2018 13:26:31 +0800 From: kbuild test robot <lkp@xxxxxxxxx> To: kbuild@xxxxxx Cc: Julia Lawall <julia.lawall@xxxxxxx> Subject: Re: [PATCH 1/1] NFSv4.2 do not allocate memory under the lock CC: kbuild-all@xxxxxx In-Reply-To: <20181116162623.50517-1-olga.kornievskaia@xxxxxxxxx> References: <20181116162623.50517-1-olga.kornievskaia@xxxxxxxxx> TO: Olga Kornievskaia <olga.kornievskaia@xxxxxxxxx> CC: trond.myklebust@xxxxxxxxxxxxxxx, anna.schumaker@xxxxxxxxxx, linux-nfs@xxxxxxxxxxxxxxx CC: linux-nfs@xxxxxxxxxxxxxxx Hi Olga, Thank you for the patch! Perhaps something to improve: [auto build test WARNING on nfs/linux-next] [also build test WARNING on v4.20-rc3 next-20181119] [if your patch is applied to the wrong git tree, please drop us a note to help improve the system] url: https://github.com/0day-ci/linux/commits/Olga-Kornievskaia/NFSv4-2-do-not-allocate-memory-under-the-lock/20181119-202157 base: git://git.linux-nfs.org/projects/trondmy/linux-nfs.git linux-next :::::: branch date: 17 hours ago :::::: commit date: 17 hours ago >> fs/nfs/callback_proc.c:714:10-14: ERROR: invalid reference to the index variable of the iterator on line 700 fs/nfs/callback_proc.c:718:8-12: ERROR: invalid reference to the index variable of the iterator on line 700 # https://github.com/0day-ci/linux/commit/65d4b7555e18c7c43f4410c07503c9b5e06dd75e git remote add linux-review https://github.com/0day-ci/linux git remote update linux-review git checkout 65d4b7555e18c7c43f4410c07503c9b5e06dd75e vim +714 fs/nfs/callback_proc.c 62164f317 Olga Kornievskaia 2018-07-09 683 62164f317 Olga Kornievskaia 2018-07-09 684 __be32 nfs4_callback_offload(void *data, void *dummy, 5178a125f Olga Kornievskaia 2018-07-09 685 struct cb_process_state *cps) 5178a125f Olga Kornievskaia 2018-07-09 686 { 62164f317 Olga Kornievskaia 2018-07-09 687 struct cb_offloadargs *args = data; 62164f317 Olga Kornievskaia 2018-07-09 688 struct nfs_server *server; 62164f317 Olga Kornievskaia 2018-07-09 689 struct nfs4_copy_state *copy; bc0c9079b Olga Kornievskaia 2018-07-09 690 bool found = false; 62164f317 Olga Kornievskaia 2018-07-09 691 65d4b7555 Olga Kornievskaia 2018-11-16 692 copy = kzalloc(sizeof(struct nfs4_copy_state), GFP_NOFS); 65d4b7555 Olga Kornievskaia 2018-11-16 693 if (!copy) 65d4b7555 Olga Kornievskaia 2018-11-16 694 return htonl(NFS4ERR_SERVERFAULT); 65d4b7555 Olga Kornievskaia 2018-11-16 695 bc0c9079b Olga Kornievskaia 2018-07-09 696 spin_lock(&cps->clp->cl_lock); 62164f317 Olga Kornievskaia 2018-07-09 697 rcu_read_lock(); 62164f317 Olga Kornievskaia 2018-07-09 698 list_for_each_entry_rcu(server, &cps->clp->cl_superblocks, 62164f317 Olga Kornievskaia 2018-07-09 699 client_link) { 62164f317 Olga Kornievskaia 2018-07-09 @700 list_for_each_entry(copy, &server->ss_copies, copies) { 62164f317 Olga Kornievskaia 2018-07-09 701 if (memcmp(args->coa_stateid.other, 62164f317 Olga Kornievskaia 2018-07-09 702 copy->stateid.other, 62164f317 Olga Kornievskaia 2018-07-09 703 sizeof(args->coa_stateid.other))) 62164f317 Olga Kornievskaia 2018-07-09 704 continue; 62164f317 Olga Kornievskaia 2018-07-09 705 nfs4_copy_cb_args(copy, args); 62164f317 Olga Kornievskaia 2018-07-09 706 complete(©->completion); bc0c9079b Olga Kornievskaia 2018-07-09 707 found = true; 62164f317 Olga Kornievskaia 2018-07-09 708 goto out; 62164f317 Olga Kornievskaia 2018-07-09 709 } 62164f317 Olga Kornievskaia 2018-07-09 710 } 62164f317 Olga Kornievskaia 2018-07-09 711 out: 62164f317 Olga Kornievskaia 2018-07-09 712 rcu_read_unlock(); bc0c9079b Olga Kornievskaia 2018-07-09 713 if (!found) { bc0c9079b Olga Kornievskaia 2018-07-09 @714 memcpy(©->stateid, &args->coa_stateid, NFS4_STATEID_SIZE); :::::: The code at line 714 was first introduced by commit :::::: bc0c9079b48ddcf1f8a6e1aaa277288b263c78d8 NFS handle COPY reply CB_OFFLOAD call race :::::: TO: Olga Kornievskaia <kolga@xxxxxxxxxx> :::::: CC: Anna Schumaker <Anna.Schumaker@xxxxxxxxxx> --- 0-DAY kernel test infrastructure Open Source Technology Center https://lists.01.org/pipermail/kbuild-all Intel Corporation
