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charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-AuthSource: PH0PR11MB5880.namprd11.prod.outlook.com X-MS-Exchange-CrossTenant-Network-Message-Id: 170f0dc4-800e-4de9-2732-08da0df28407 X-MS-Exchange-CrossTenant-originalarrivaltime: 25 Mar 2022 00:00:47.3872 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 46c98d88-e344-4ed4-8496-4ed7712e255d X-MS-Exchange-CrossTenant-mailboxtype: HOSTED X-MS-Exchange-CrossTenant-userprincipalname: BpM8QMnyFgnPHUs0ELV6Sd2UPYzzMsMCY9fAecLUhjQyoa0SDcbELNj++LZvE0w8XF71aFR0fzwlQSV09jUDhQ== X-MS-Exchange-Transport-CrossTenantHeadersStamped: PH7PR11MB6054 X-OriginatorOrg: intel.com Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Mar 24, 2022 at 07:15:15PM +0800, Zqiang wrote: > The boost kthreads may spawn failed, although the probability of=20 > creation failure is very low, in consideration of the robustness of=20 > the code, add boost_kthread_task pointer detection. >=20 > Signed-off-by: Zqiang > >Good catch! As you say, rare, but definitely worth fixing. > >I could not resist a bit of wordsmithing. Could you please check to see i= f I messed something up? Thanks wordsmithing, I think it's ok. Thanks, Zqiang > > Thanx, Paul > >------------------------------------------------------------------------ > >commit ad3c438e248cbc41fe30a41287621c3dbfcdf51c >Author: Zqiang >Date: Thu Mar 24 19:15:15 2022 +0800 > > rcu: Check for successful spawn of ->boost_kthread_task > =20 > For the spawning of the priority-boost kthreads can fail, improbable > though this might seem. This commit therefore refrains from attemotin= g > to initiate RCU priority boosting when The ->boost_kthread_task pointe= r > is NULL. > =20 > Signed-off-by: Zqiang > Signed-off-by: Paul E. McKenney > >diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h index 6b9= bcd45c7b2..d58f6d6073bf 100644 >--- a/kernel/rcu/tree_plugin.h >+++ b/kernel/rcu/tree_plugin.h >@@ -1125,7 +1125,8 @@ static void rcu_initiate_boost(struct rcu_node *rnp,= unsigned long flags) > __releases(rnp->lock) > { > raw_lockdep_assert_held_rcu_node(rnp); >- if (!rcu_preempt_blocked_readers_cgp(rnp) && rnp->exp_tasks =3D=3D NULL)= { >+ if (!rnp->boost_kthread_task || >+ (!rcu_preempt_blocked_readers_cgp(rnp) && !rnp->exp_tasks)) { > raw_spin_unlock_irqrestore_rcu_node(rnp, flags); > return; > }