From patchwork Sun Mar 31 00:04:40 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Paul Walmsley X-Patchwork-Id: 2368121 Return-Path: X-Original-To: patchwork-linux-omap@patchwork.kernel.org Delivered-To: patchwork-process-083081@patchwork2.kernel.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by patchwork2.kernel.org (Postfix) with ESMTP id A7F1EDF24C for ; Sun, 31 Mar 2013 00:05:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754698Ab3CaAEn (ORCPT ); Sat, 30 Mar 2013 20:04:43 -0400 Received: from utopia.booyaka.com ([74.50.51.50]:35648 "EHLO utopia.booyaka.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754643Ab3CaAEl (ORCPT ); Sat, 30 Mar 2013 20:04:41 -0400 Received: (qmail 15021 invoked by uid 1019); 31 Mar 2013 00:04:40 -0000 Date: Sun, 31 Mar 2013 00:04:40 +0000 (UTC) From: Paul Walmsley To: Mandeep Singh Baines , Andrew Morton , Linus Torvalds cc: linux-kernel@vger.kernel.org, linux-omap@vger.kernel.org, Jeff Layton , Shawn Guo , maciej.rutecki@gmail.com, Fengguang Wu , Trond Myklebust , Ingo Molnar , Ben Chan , Oleg Nesterov , Tejun Heo , "Rafael J. Wysocki" Subject: [PATCH] Revert "lockdep: check that no locks held at freeze time" Message-ID: User-Agent: Alpine 2.00 (DEB 1167 2008-08-23) MIME-Version: 1.0 Sender: linux-omap-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-omap@vger.kernel.org This reverts commit 6aa9707099c4b25700940eb3d016f16c4434360d. Commit 6aa970 causes problems with NFS root filesystems. The failures were noticed on OMAP2 and 3 boards during kernel init: [ 5.508148] [ BUG: swapper/0/1 still has locks held! ] [ 5.513610] 3.9.0-rc3-00344-ga937536 #1 Not tainted [ 5.518798] ------------------------------------- [ 5.523773] 1 lock held by swapper/0/1: [ 5.527893] #0: (&type->s_umount_key#13/1){+.+.+.}, at: [] sget+0x248/0x574 [ 5.536437] [ 5.536437] stack backtrace: [ 5.541107] [] (unwind_backtrace+0x0/0xf0) from [] (rpc_wait_bit_killable+0x98/0xcc) [ 5.551208] [] (rpc_wait_bit_killable+0x98/0xcc) from [] (__wait_on_bit+0x74/0xb8) [ 5.561096] [] (__wait_on_bit+0x74/0xb8) from [] (out_of_line_wait_on_bit+0x6c/0x78) [ 5.571166] [] (out_of_line_wait_on_bit+0x6c/0x78) from [] (__rpc_execute+0xf0/0x360) [ 5.581329] [] (__rpc_execute+0xf0/0x360) from [] (rpc_run_task+0x98/0xa4) [ 5.590515] [] (rpc_run_task+0x98/0xa4) from [] (rpc_call_sync+0x48/0xb4) [ 5.599578] [] (rpc_call_sync+0x48/0xb4) from [] (nfs_proc_get_root+0x48/0x124) [ 5.609191] [] (nfs_proc_get_root+0x48/0x124) from [] (nfs_get_root+0x58/0x190) [ 5.618804] [] (nfs_get_root+0x58/0x190) from [] (nfs_fs_mount_common+0x98/0x158) [ 5.628601] [] (nfs_fs_mount_common+0x98/0x158) from [] (nfs_try_mount+0x144/0x214) [ 5.638580] [] (nfs_try_mount+0x144/0x214) from [] (nfs_fs_mount+0x178/0x850) [ 5.648010] [] (nfs_fs_mount+0x178/0x850) from [] (mount_fs+0x44/0x184) [ 5.656860] [] (mount_fs+0x44/0x184) from [] (vfs_kern_mount+0x4c/0xc0) [ 5.665740] [] (vfs_kern_mount+0x4c/0xc0) from [] (do_mount+0x6d0/0x858) [ 5.674682] [] (do_mount+0x6d0/0x858) from [] (sys_mount+0x84/0xb8) [ 5.683197] [] (sys_mount+0x84/0xb8) from [] (do_mount_root+0x24/0xb0) [ 5.691986] [] (do_mount_root+0x24/0xb0) from [] (mount_root+0x50/0xf8) [ 5.700866] [] (mount_root+0x50/0xf8) from [] (prepare_namespace+0x160/0x1c4) [ 5.710296] [] (prepare_namespace+0x160/0x1c4) from [] (kernel_init_freeable+0x17c/0x1c4) [ 5.720825] [] (kernel_init_freeable+0x17c/0x1c4) from [] (kernel_init+0x8/0xe4) [ 5.730529] [] (kernel_init+0x8/0xe4) from [] (ret_from_fork+0x14/0x24) Although the rootfs mounts, the system is unstable. Here's a transcript from a PM test: http://www.pwsan.com/omap/testlogs/test_v3.9-rc3/20130317194234/pm/37xxevm/37xxevm_log.txt Here's what the test log should look like: http://www.pwsan.com/omap/testlogs/test_v3.8/20130218214403/pm/37xxevm/37xxevm_log.txt Mailing list discussion is here: http://lkml.org/lkml/2013/3/4/221 Deal with this for v3.9 by reverting the problem commit, until folks can figure out the right long-term course of action. Signed-off-by: Paul Walmsley Cc: Mandeep Singh Baines Cc: Jeff Layton Cc: Shawn Guo Cc: Cc: Fengguang Wu Cc: Trond Myklebust Cc: Ingo Molnar Cc: Ben Chan Cc: Oleg Nesterov Cc: Tejun Heo Cc: Rafael J. Wysocki Cc: Andrew Morton Cc: Linus Torvalds Acked-by: Shawn Guo --- include/linux/debug_locks.h | 4 ++-- include/linux/freezer.h | 3 --- kernel/exit.c | 2 +- kernel/lockdep.c | 17 +++++++++-------- 4 files changed, 12 insertions(+), 14 deletions(-) diff --git a/include/linux/debug_locks.h b/include/linux/debug_locks.h index a975de1..3bd46f7 100644 --- a/include/linux/debug_locks.h +++ b/include/linux/debug_locks.h @@ -51,7 +51,7 @@ struct task_struct; extern void debug_show_all_locks(void); extern void debug_show_held_locks(struct task_struct *task); extern void debug_check_no_locks_freed(const void *from, unsigned long len); -extern void debug_check_no_locks_held(void); +extern void debug_check_no_locks_held(struct task_struct *task); #else static inline void debug_show_all_locks(void) { @@ -67,7 +67,7 @@ debug_check_no_locks_freed(const void *from, unsigned long len) } static inline void -debug_check_no_locks_held(void) +debug_check_no_locks_held(struct task_struct *task) { } #endif diff --git a/include/linux/freezer.h b/include/linux/freezer.h index 043a5cf..e70df40 100644 --- a/include/linux/freezer.h +++ b/include/linux/freezer.h @@ -3,7 +3,6 @@ #ifndef FREEZER_H_INCLUDED #define FREEZER_H_INCLUDED -#include #include #include #include @@ -49,8 +48,6 @@ extern void thaw_kernel_threads(void); static inline bool try_to_freeze(void) { - if (!(current->flags & PF_NOFREEZE)) - debug_check_no_locks_held(); might_sleep(); if (likely(!freezing(current))) return false; diff --git a/kernel/exit.c b/kernel/exit.c index 51e485c..60bc027 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -835,7 +835,7 @@ void do_exit(long code) /* * Make sure we are holding no locks: */ - debug_check_no_locks_held(); + debug_check_no_locks_held(tsk); /* * We can do this unlocked here. The futex code uses this flag * just to verify whether the pi state cleanup has been done diff --git a/kernel/lockdep.c b/kernel/lockdep.c index 259db20..8a0efac 100644 --- a/kernel/lockdep.c +++ b/kernel/lockdep.c @@ -4088,7 +4088,7 @@ void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len) } EXPORT_SYMBOL_GPL(debug_check_no_locks_freed); -static void print_held_locks_bug(void) +static void print_held_locks_bug(struct task_struct *curr) { if (!debug_locks_off()) return; @@ -4097,21 +4097,22 @@ static void print_held_locks_bug(void) printk("\n"); printk("=====================================\n"); - printk("[ BUG: %s/%d still has locks held! ]\n", - current->comm, task_pid_nr(current)); + printk("[ BUG: lock held at task exit time! ]\n"); print_kernel_ident(); printk("-------------------------------------\n"); - lockdep_print_held_locks(current); + printk("%s/%d is exiting with locks still held!\n", + curr->comm, task_pid_nr(curr)); + lockdep_print_held_locks(curr); + printk("\nstack backtrace:\n"); dump_stack(); } -void debug_check_no_locks_held(void) +void debug_check_no_locks_held(struct task_struct *task) { - if (unlikely(current->lockdep_depth > 0)) - print_held_locks_bug(); + if (unlikely(task->lockdep_depth > 0)) + print_held_locks_bug(task); } -EXPORT_SYMBOL_GPL(debug_check_no_locks_held); void debug_show_all_locks(void) {