4.9-stable review patch. If anyone has any objections, please let me know. ------------------ From: Tahsin Erdogan <tahsin@xxxxxxxxxx> commit 40e952f9d687928b32db20226f085ae660a7237c upstream. 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 lock_acquire+0xcc/0x200 del_timer_sync+0x3c/0xc0 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") Link: http://lkml.kernel.org/r/20170306192122.24262-1-tahsin@xxxxxxxxxx Signed-off-by: Tahsin Erdogan <tahsin@xxxxxxxxxx> Acked-by: Michal Hocko <mhocko@xxxxxxxx> Cc: Johannes Weiner <hannes@xxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- mm/memcontrol.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -4139,17 +4139,22 @@ static void free_mem_cgroup_per_node_inf 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; @@ -4200,7 +4205,7 @@ static struct mem_cgroup *mem_cgroup_all fail: if (memcg->id.id > 0) idr_remove(&mem_cgroup_idr, memcg->id.id); - mem_cgroup_free(memcg); + __mem_cgroup_free(memcg); return NULL; }