From mboxrd@z Thu Jan 1 00:00:00 1970 Subject: Re: [PATCH 2/2] Make res_counter hierarchical In-Reply-To: Your message of "Thu, 13 Mar 2008 08:05:41 +0900 (JST)" <20080312230541.CB9021E703D@siro.lan> References: <20080312230541.CB9021E703D@siro.lan> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Message-Id: <20080312233650.363181E705C@siro.lan> Date: Thu, 13 Mar 2008 08:36:50 +0900 (JST) From: yamamoto@valinux.co.jp (YAMAMOTO Takashi) Sender: owner-linux-mm@kvack.org Return-Path: To: xemul@openvz.org Cc: containers@lists.osdl.org, linux-mm@kvack.org, menage@google.com, balbir@linux.vnet.ibm.com List-ID: > > @@ -36,10 +37,26 @@ int res_counter_charge(struct res_counter *counter, unsigned long val) > > { > > int ret; > > unsigned long flags; > > + struct res_counter *c, *unroll_c; > > + > > + local_irq_save(flags); > > + for (c = counter; c != NULL; c = c->parent) { > > + spin_lock(&c->lock); > > + ret = res_counter_charge_locked(c, val); > > + spin_unlock(&c->lock); > > + if (ret < 0) > > + goto unroll; > > + } > > + local_irq_restore(flags); > > + return 0; > > > > - spin_lock_irqsave(&counter->lock, flags); > > - ret = res_counter_charge_locked(counter, val); > > - spin_unlock_irqrestore(&counter->lock, flags); > > +unroll: > > + for (unroll_c = counter; unroll_c != c; unroll_c = unroll_c->parent) { > > + spin_lock(&unroll_c->lock); > > + res_counter_uncharge_locked(unroll_c, val); > > + spin_unlock(&unroll_c->lock); > > + } > > + local_irq_restore(flags); > > return ret; > > } > > what prevents the topology (in particular, ->parent pointers) from > changing behind us? > > YAMAMOTO Takashi to answer myself: cgroupfs rename doesn't allow topological changes in the first place. btw, i think you need to do the same for res_counter_limit_check_locked as well. i'm skeptical about doing these complicated stuffs in kernel, esp. in this potentially performance critical code. YAMAMOTO Takashi -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org