From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0b-00082601.pphosted.com ([67.231.153.30]:56610 "EHLO mx0b-00082601.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751305AbaFMOKD (ORCPT ); Fri, 13 Jun 2014 10:10:03 -0400 Message-ID: <539B06C0.6020606@fb.com> Date: Fri, 13 Jun 2014 10:12:16 -0400 From: Chris Mason MIME-Version: 1.0 To: , "linux-btrfs@vger.kernel.org" Subject: Re: [PATCH v2] Btrfs: fix RCU correctness warning when running sanity tests References: <1402423961-12169-1-git-send-email-fdmanana@gmail.com> <1402424236-13459-1-git-send-email-fdmanana@gmail.com> In-Reply-To: Content-Type: text/plain; charset="ISO-8859-1" Sender: linux-btrfs-owner@vger.kernel.org List-ID: On 06/13/2014 05:09 AM, Filipe David Manana wrote: > On Tue, Jun 10, 2014 at 7:17 PM, Filipe David Borba Manana > wrote: >> When CONFIG_PROVE_RCU=y and CONFIG_PROVE_RCU_REPEATEDLY=y, the >> following was dumped in dmesg: >> >> [ 3197.218064] =============================== >> [ 3197.218064] [ INFO: suspicious RCU usage. ] >> [ 3197.218066] 3.15.0-rc8-fdm-btrfs-next-33+ #4 Not tainted >> [ 3197.218067] ------------------------------- >> [ 3197.218068] include/linux/radix-tree.h:196 suspicious rcu_dereference_check() usage! >> [ 3197.218068] >> [ 3197.218068] other info that might help us debug this: >> [ 3197.218068] >> [ 3197.218070] >> [ 3197.218070] rcu_scheduler_active = 1, debug_locks = 1 >> [ 3197.218071] 1 lock held by modprobe/12024: >> [ 3197.218072] #0: (&(&fs_info->buffer_lock)->rlock){+.+...}, at: [] btrfs_free_dummy_root+0x5a/0x1d0 [btrfs] >> [ 3197.218093] >> [ 3197.218093] stack backtrace: >> [ 3197.218095] CPU: 3 PID: 12024 Comm: modprobe Not tainted 3.15.0-rc8-fdm-btrfs-next-33+ #4 >> [ 3197.218096] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 >> [ 3197.218097] 0000000000000001 ffff8800af18fc18 ffffffff81685c5a 000000000000feb0 >> [ 3197.218099] ffff8800cf6ccb40 ffff8800af18fc48 ffffffff810a6316 ffff8801d955f640 >> [ 3197.218101] ffff8800d719e328 ffff8800d719e370 ffff8800d719c000 ffff8800af18fcb8 >> [ 3197.218102] Call Trace: >> [ 3197.218105] [] dump_stack+0x4e/0x68 >> [ 3197.218108] [] lockdep_rcu_suspicious+0xe6/0x130 >> [ 3197.218119] [] btrfs_free_dummy_root+0x188/0x1d0 [btrfs] >> [ 3197.218129] [] btrfs_test_qgroups+0xea/0x1bb [btrfs] >> [ 3197.218137] [] ? ftrace_define_fields_btrfs_space_reservation+0xfd/0xfd [btrfs] >> [ 3197.218144] [] ? ftrace_define_fields_btrfs_space_reservation+0xfd/0xfd [btrfs] >> [ 3197.218151] [] init_btrfs_fs+0xe5/0x184 [btrfs] >> [ 3197.218154] [] do_one_initcall+0x102/0x150 >> [ 3197.218157] [] ? set_memory_nx+0x43/0x50 >> [ 3197.218160] [] ? set_section_ro_nx+0x6d/0x74 >> [ 3197.218162] [] load_module+0x1cdc/0x2630 >> [ 3197.218164] [] ? show_initstate+0x60/0x60 >> [ 3197.218166] [] SyS_finit_module+0x8e/0x90 >> [ 3197.218168] [] system_call_fastpath+0x16/0x1b >> >> Signed-off-by: Filipe David Borba Manana > > Chris, > > Please drop this patch from your integration branch. > Sasha fixed this too but in a simpler way: > https://urldefense.proofpoint.com/v1/url?u=https://patchwork.kernel.org/patch/4337091/&k=ZVNjlDMF0FElm4dQtryO4A%3D%3D%0A&r=6%2FL0lzzDhu0Y1hL9xm%2BQyA%3D%3D%0A&m=udAT%2BO62eFj7qxpld6pYEp%2FRKmeGPjqGP8i%2Fb8%2FcJ2s%3D%0A&s=e3bbde8e6b7bd327f6f32a8f959089bed8f4a25a27fa8b0ddf2589cf70b8a89f > (In fact both patches applied probably trigger another warning the rcu Thanks, it did look overlapping to me, was going to sort it out in the morning. -chris