From patchwork Thu Dec 6 03:24:15 2012 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Subject: [3.5.y.z, extended, stable] Patch "xen/events: fix RCU warning, or Call idle notifier after" has been added to staging queue Date: Wed, 05 Dec 2012 17:24:15 -0000 From: Herton Ronaldo Krzesinski X-Patchwork-Id: 204111 Message-Id: <1354764255-28999-1-git-send-email-herton.krzesinski@canonical.com> To: Mojiong Qiu Cc: kernel-team@lists.ubuntu.com, Konrad Rzeszutek Wilk , Mojiong Qiu This is a note to let you know that I have just added a patch titled xen/events: fix RCU warning, or Call idle notifier after to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree which can be found at: http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.5.y-queue If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.5.y.z tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Herton ------ >From 06848989ab3961fb5970078e7b147b7cb6850c10 Mon Sep 17 00:00:00 2001 From: Mojiong Qiu Date: Tue, 6 Nov 2012 16:08:15 +0800 Subject: [PATCH] xen/events: fix RCU warning, or Call idle notifier after irq_enter() X-Extended-Stable: 3.5 commit 772aebcefeff310f80e32b874988af0076cb799d upstream. exit_idle() should be called after irq_enter(), otherwise it throws: [ INFO: suspicious RCU usage. ] 3.6.5 #1 Not tainted ------------------------------- include/linux/rcupdate.h:725 rcu_read_lock() used illegally while idle! other info that might help us debug this: RCU used illegally from idle CPU! rcu_scheduler_active = 1, debug_locks = 1 RCU used illegally from extended quiescent state! 1 lock held by swapper/0/0: #0: (rcu_read_lock){......}, at: [] __atomic_notifier_call_chain+0x0/0x140 stack backtrace: Pid: 0, comm: swapper/0 Not tainted 3.6.5 #1 Call Trace: [] lockdep_rcu_suspicious+0xe2/0x130 [] __atomic_notifier_call_chain+0x12c/0x140 [] ? atomic_notifier_chain_unregister+0x90/0x90 [] ? trace_hardirqs_off+0xd/0x10 [] atomic_notifier_call_chain+0x16/0x20 [] exit_idle+0x43/0x50 [] xen_evtchn_do_upcall+0x25/0x50 [] xen_do_hypervisor_callback+0x1e/0x30 [] ? hypercall_page+0x3aa/0x1000 [] ? hypercall_page+0x3aa/0x1000 [] ? xen_safe_halt+0x10/0x20 [] ? default_idle+0xba/0x570 [] ? cpu_idle+0xdf/0x140 [] ? rest_init+0x135/0x144 [] ? csum_partial_copy_generic+0x16c/0x16c [] ? start_kernel+0x3db/0x3e8 [] ? repair_env_string+0x5a/0x5a [] ? x86_64_start_reservations+0x131/0x135 [] ? xen_start_kernel+0x465/0x46 Git commit 98ad1cc14a5c4fd658f9d72c6ba5c86dfd3ce0d5 Author: Frederic Weisbecker Date: Fri Oct 7 18:22:09 2011 +0200 x86: Call idle notifier after irq_enter() did this, but it missed the Xen code. Signed-off-by: Mojiong Qiu Signed-off-by: Konrad Rzeszutek Wilk [ herton: rediff for 3.5, no ifdef around exit_idle() ] Signed-off-by: Herton Ronaldo Krzesinski --- drivers/xen/events.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) -- 1.7.9.5 diff --git a/drivers/xen/events.c b/drivers/xen/events.c index 7595581..99c5345 100644 --- a/drivers/xen/events.c +++ b/drivers/xen/events.c @@ -1374,8 +1374,8 @@ void xen_evtchn_do_upcall(struct pt_regs *regs) { struct pt_regs *old_regs = set_irq_regs(regs); - exit_idle(); irq_enter(); + exit_idle(); __xen_evtchn_do_upcall();