On Mon, 18 Oct 2010 17:39:41 -0700 Greg Thelen <gthelen@xxxxxxxxxx> wrote: > From: Balbir Singh <balbir@xxxxxxxxxxxxxxxxxx> > > memcg has lockdep warnings (sleep inside rcu lock) > > From: Balbir Singh <balbir@xxxxxxxxxxxxxxxxxx> > > Recent move to get_online_cpus() ends up calling get_online_cpus() from > mem_cgroup_read_stat(). However mem_cgroup_read_stat() is called under rcu > lock. get_online_cpus() can sleep. The dirty limit patches expose > this BUG more readily due to their usage of mem_cgroup_page_stat() > > This patch address this issue as identified by lockdep and moves the > hotplug protection to a higher layer. This might increase the time > required to hotplug, but not by much. > > Warning messages > > BUG: sleeping function called from invalid context at kernel/cpu.c:62 > in_atomic(): 0, irqs_disabled(): 0, pid: 6325, name: pagetest > 2 locks held by pagetest/6325: > do_page_fault+0x27d/0x4a0 > mem_cgroup_page_stat+0x0/0x23f > Pid: 6325, comm: pagetest Not tainted 2.6.36-rc5-mm1+ #201 > Call Trace: > [<ffffffff81041224>] __might_sleep+0x12d/0x131 > [<ffffffff8104f4af>] get_online_cpus+0x1c/0x51 > [<ffffffff8110eedb>] mem_cgroup_read_stat+0x27/0xa3 > [<ffffffff811125d2>] mem_cgroup_page_stat+0x131/0x23f > [<ffffffff811124a1>] ? mem_cgroup_page_stat+0x0/0x23f > [<ffffffff810d57c3>] global_dirty_limits+0x42/0xf8 > [<ffffffff810d58b3>] throttle_vm_writeout+0x3a/0xb4 > [<ffffffff810dc2f8>] shrink_zone+0x3e6/0x3f8 > [<ffffffff81074a35>] ? ktime_get_ts+0xb2/0xbf > [<ffffffff810dd1aa>] do_try_to_free_pages+0x106/0x478 > [<ffffffff810dd601>] try_to_free_mem_cgroup_pages+0xe5/0x14c > [<ffffffff8110f947>] mem_cgroup_hierarchical_reclaim+0x314/0x3a2 > [<ffffffff81111b31>] __mem_cgroup_try_charge+0x29b/0x593 > [<ffffffff8111194a>] ? __mem_cgroup_try_charge+0xb4/0x593 > [<ffffffff81071258>] ? local_clock+0x40/0x59 > [<ffffffff81009015>] ? sched_clock+0x9/0xd > [<ffffffff810710d5>] ? sched_clock_local+0x1c/0x82 > [<ffffffff8111398a>] mem_cgroup_charge_common+0x4b/0x76 > [<ffffffff81141469>] ? bio_add_page+0x36/0x38 > [<ffffffff81113ba9>] mem_cgroup_cache_charge+0x1f4/0x214 > [<ffffffff810cd195>] add_to_page_cache_locked+0x4a/0x148 > .... > > Acked-by: Greg Thelen <gthelen@xxxxxxxxxx> > Signed-off-by: Balbir Singh <balbir@xxxxxxxxxxxxxxxxxx> Acked-by: Daisuke Nishimura <nishimura@xxxxxxxxxxxxxxxxx> -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>