The patch titled Subject: cgroup: revert ss_id_lock to spinlock has been removed from the -mm tree. Its filename was cgroup-revert-ss_id_lock-to-spinlock.patch This patch was dropped because it was merged into mainline or a subsystem tree The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/ ------------------------------------------------------ From: Hugh Dickins <hughd@xxxxxxxxxx> Subject: cgroup: revert ss_id_lock to spinlock Commit c1e2ee2dc436 "memcg: replace ss->id_lock with a rwlock" has now been seen to cause the unfair behavior we should have expected from converting a spinlock to an rwlock: softlockup in cgroup_mkdir(), whose get_new_cssid() is waiting for the wlock, while there are 19 tasks using the rlock in css_get_next() to get on with their memcg workload (in an artificial test, admittedly). Yet lib/idr.c was made suitable for RCU way back: revert that commit, restoring ss->id_lock to a spinlock. Signed-off-by: Hugh Dickins <hughd@xxxxxxxxxx> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx> Acked-by: Li Zefan <lizf@xxxxxxxxxxxxxx> Cc: Eric Dumazet <eric.dumazet@xxxxxxxxx> Acked-by: Tejun Heo <tj@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- include/linux/cgroup.h | 2 +- kernel/cgroup.c | 18 +++++++++--------- 2 files changed, 10 insertions(+), 10 deletions(-) diff -puN include/linux/cgroup.h~cgroup-revert-ss_id_lock-to-spinlock include/linux/cgroup.h --- a/include/linux/cgroup.h~cgroup-revert-ss_id_lock-to-spinlock +++ a/include/linux/cgroup.h @@ -498,7 +498,7 @@ struct cgroup_subsys { struct list_head sibling; /* used when use_id == true */ struct idr idr; - rwlock_t id_lock; + spinlock_t id_lock; /* should be defined only by modular subsystems */ struct module *module; diff -puN kernel/cgroup.c~cgroup-revert-ss_id_lock-to-spinlock kernel/cgroup.c --- a/kernel/cgroup.c~cgroup-revert-ss_id_lock-to-spinlock +++ a/kernel/cgroup.c @@ -4885,9 +4885,9 @@ void free_css_id(struct cgroup_subsys *s rcu_assign_pointer(id->css, NULL); rcu_assign_pointer(css->id, NULL); - write_lock(&ss->id_lock); + spin_lock(&ss->id_lock); idr_remove(&ss->idr, id->id); - write_unlock(&ss->id_lock); + spin_unlock(&ss->id_lock); kfree_rcu(id, rcu_head); } EXPORT_SYMBOL_GPL(free_css_id); @@ -4913,10 +4913,10 @@ static struct css_id *get_new_cssid(stru error = -ENOMEM; goto err_out; } - write_lock(&ss->id_lock); + spin_lock(&ss->id_lock); /* Don't use 0. allocates an ID of 1-65535 */ error = idr_get_new_above(&ss->idr, newid, 1, &myid); - write_unlock(&ss->id_lock); + spin_unlock(&ss->id_lock); /* Returns error when there are no free spaces for new ID.*/ if (error) { @@ -4931,9 +4931,9 @@ static struct css_id *get_new_cssid(stru return newid; remove_idr: error = -ENOSPC; - write_lock(&ss->id_lock); + spin_lock(&ss->id_lock); idr_remove(&ss->idr, myid); - write_unlock(&ss->id_lock); + spin_unlock(&ss->id_lock); err_out: kfree(newid); return ERR_PTR(error); @@ -4945,7 +4945,7 @@ static int __init_or_module cgroup_init_ { struct css_id *newid; - rwlock_init(&ss->id_lock); + spin_lock_init(&ss->id_lock); idr_init(&ss->idr); newid = get_new_cssid(ss, 0); @@ -5040,9 +5040,9 @@ css_get_next(struct cgroup_subsys *ss, i * scan next entry from bitmap(tree), tmpid is updated after * idr_get_next(). */ - read_lock(&ss->id_lock); + spin_lock(&ss->id_lock); tmp = idr_get_next(&ss->idr, &tmpid); - read_unlock(&ss->id_lock); + spin_unlock(&ss->id_lock); if (!tmp) break; _ Patches currently in -mm which might be from hughd@xxxxxxxxxx are origin.patch linux-next.patch mm-hugetlb-cleanup-duplicated-code-in-unmapping-vm-range.patch radix-tree-introduce-bit-optimized-iterator.patch radix-tree-introduce-bit-optimized-iterator-v3.patch radix-tree-introduce-bit-optimized-iterator-v3-fix.patch radix-tree-rewrite-gang-lookup-with-using-iterator.patch radix-tree-use-iterators-in-find_get_pages-functions.patch prio_tree-debugging-patch.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html