On 2014/6/25 9:57, Gu Zheng wrote: > When runing with the kernel(3.15-rc7+), the follow bug occurs: > [ 9969.258987] BUG: sleeping function called from invalid context at kernel/locking/mutex.c:586 > [ 9969.359906] in_atomic(): 1, irqs_disabled(): 0, pid: 160655, name: python > [ 9969.441175] INFO: lockdep is turned off. > [ 9969.488184] CPU: 26 PID: 160655 Comm: python Tainted: G A 3.15.0-rc7+ #85 > [ 9969.581032] Hardware name: FUJITSU-SV PRIMEQUEST 1800E/SB, BIOS PRIMEQUEST 1000 Series BIOS Version 1.39 11/16/2012 > [ 9969.706052] ffffffff81a20e60 ffff8803e941fbd0 ffffffff8162f523 ffff8803e941fd18 > [ 9969.795323] ffff8803e941fbe0 ffffffff8109995a ffff8803e941fc58 ffffffff81633e6c > [ 9969.884710] ffffffff811ba5dc ffff880405c6b480 ffff88041fdd90a0 0000000000002000 > [ 9969.974071] Call Trace: > [ 9970.003403] [<ffffffff8162f523>] dump_stack+0x4d/0x66 > [ 9970.065074] [<ffffffff8109995a>] __might_sleep+0xfa/0x130 > [ 9970.130743] [<ffffffff81633e6c>] mutex_lock_nested+0x3c/0x4f0 > [ 9970.200638] [<ffffffff811ba5dc>] ? kmem_cache_alloc+0x1bc/0x210 > [ 9970.272610] [<ffffffff81105807>] cpuset_mems_allowed+0x27/0x140 > [ 9970.344584] [<ffffffff811b1303>] ? __mpol_dup+0x63/0x150 > [ 9970.409282] [<ffffffff811b1385>] __mpol_dup+0xe5/0x150 > [ 9970.471897] [<ffffffff811b1303>] ? __mpol_dup+0x63/0x150 > [ 9970.536585] [<ffffffff81068c86>] ? copy_process.part.23+0x606/0x1d40 > [ 9970.613763] [<ffffffff810bf28d>] ? trace_hardirqs_on+0xd/0x10 > [ 9970.683660] [<ffffffff810ddddf>] ? monotonic_to_bootbased+0x2f/0x50 > [ 9970.759795] [<ffffffff81068cf0>] copy_process.part.23+0x670/0x1d40 > [ 9970.834885] [<ffffffff8106a598>] do_fork+0xd8/0x380 > [ 9970.894375] [<ffffffff81110e4c>] ? __audit_syscall_entry+0x9c/0xf0 > [ 9970.969470] [<ffffffff8106a8c6>] SyS_clone+0x16/0x20 > [ 9971.030011] [<ffffffff81642009>] stub_clone+0x69/0x90 > [ 9971.091573] [<ffffffff81641c29>] ? system_call_fastpath+0x16/0x1b > > The cause is that cpuset_mems_allowed() try to take mutex_lock(&callback_mutex) > under the rcu_read_lock(which was hold in __mpol_dup()). And in cpuset_mems_allowed(), > the access to cpuset is under rcu_read_lock, so in __mpol_dup, we can reduce the > rcu_read_lock protection region to protect the access to cpuset only in > current_cpuset_is_being_rebound(). So that we can avoid this bug. > This patch is a temporary solution that just addresses the bug mentioned above, > can not fix the long-standing issue about cpuset.mems rebinding on fork(): > " > When the forker's task_struct is duplicated (which includes ->mems_allowed) > and it races with an update to cpuset_being_rebound in update_tasks_nodemask() > then the task's mems_allowed doesn't get updated. And the child task's > mems_allowed can be wrong if the cpuset's nodemask changes before the > child has been added to the cgroup's tasklist. > " > > Signed-off-by: Gu Zheng <guz.fnst@xxxxxxxxxxxxxx> > Cc: stable <stable@xxxxxxxxxxxxxxx> Acked-by: Li Zefan <lizefan@xxxxxxxxxx> -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>