[CC Andrew]
On Mon 06-03-17 11:21:22, Tahsin Erdogan wrote:
> mem_cgroup_free() indirectly calls wb_domain_exit() which is not
> prepared to deal with a struct wb_domain object that hasn't executed
> wb_domain_init(). For instance, the following warning message is
> printed by lockdep if alloc_percpu() fails in mem_cgroup_alloc():
>
> INFO: trying to register non-static key.
> the code is fine but needs lockdep annotation.
> turning off the locking correctness validator.
> CPU: 1 PID: 1950 Comm: mkdir Not tainted 4.10.0+ #151
> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
> Call Trace:
> dump_stack+0x67/0x99
> register_lock_class+0x36d/0x540
> __lock_acquire+0x7f/0x1a30
> ? irq_work_queue+0x73/0x90
> ? wake_up_klogd+0x36/0x40
> ? console_unlock+0x45d/0x540
> ? vprintk_emit+0x211/0x2e0
> lock_acquire+0xcc/0x200
> ? try_to_del_timer_sync+0x60/0x60
> del_timer_sync+0x3c/0xc0
> ? try_to_del_timer_sync+0x60/0x60
> wb_domain_exit+0x14/0x20
> mem_cgroup_free+0x14/0x40
> mem_cgroup_css_alloc+0x3f9/0x620
> cgroup_apply_control_enable+0x190/0x390
> cgroup_mkdir+0x290/0x3d0
> kernfs_iop_mkdir+0x58/0x80
> vfs_mkdir+0x10e/0x1a0
> SyS_mkdirat+0xa8/0xd0
> SyS_mkdir+0x14/0x20
> entry_SYSCALL_64_fastpath+0x18/0xad
>
> Add __mem_cgroup_free() which skips wb_domain_exit(). This is
> used by both mem_cgroup_free() and mem_cgroup_alloc() clean up.
>
> Fixes: 0b8f73e104285 ("mm: memcontrol: clean up alloc, online, offline, free functions")
> Signed-off-by: Tahsin Erdogan <tahsin@xxxxxxxxxx>
> ---
> v2:
> Added __mem_cgroup_free()
>
> mm/memcontrol.c | 11 ++++++++---
> 1 file changed, 8 insertions(+), 3 deletions(-)
>
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index c52ec893e241..e7d900c5f2d0 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -4135,17 +4135,22 @@ static void free_mem_cgroup_per_node_info(struct mem_cgroup *memcg, int node)
> kfree(memcg->nodeinfo[node]);
> }
>
> -static void mem_cgroup_free(struct mem_cgroup *memcg)
> +static void __mem_cgroup_free(struct mem_cgroup *memcg)
> {
> int node;
>
> - memcg_wb_domain_exit(memcg);
> for_each_node(node)
> free_mem_cgroup_per_node_info(memcg, node);
> free_percpu(memcg->stat);
> kfree(memcg);
> }
>
> +static void mem_cgroup_free(struct mem_cgroup *memcg)
> +{
> + memcg_wb_domain_exit(memcg);
> + __mem_cgroup_free(memcg);
> +}
> +
> static struct mem_cgroup *mem_cgroup_alloc(void)
> {
> struct mem_cgroup *memcg;
> @@ -4196,7 +4201,7 @@ static struct mem_cgroup *mem_cgroup_alloc(void)
> fail:
> if (memcg->id.id > 0)
> idr_remove(&mem_cgroup_idr, memcg->id.id);
> - mem_cgroup_free(memcg);
> + __mem_cgroup_free(memcg);
> return NULL;
> }
>
> --
> 2.12.0.rc1.440.g5b76565f74-goog
--
Michal Hocko
SUSE Labs
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