hulk inclusion category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I99KM6
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When read/write memory.wb_blkio_ino of a memcg, and delete the memcg at the same time, it could cause deadlock as below: CPU0 CPU1 rlock(kn->active#4); lock(cgroup_mutex); lock(kn->active#4); lock(cgroup_mutex);
Therefore, use cgroup_kn_lock_live to replace cgroup_mutex in reading/writing memory.wb_blkio_ino.
Fixes: cf4973d8f67c ("cgroup: support cgroup writeback on cgroupv1") Signed-off-by: Chen Ridong chenridong@huawei.com --- mm/memcontrol.c | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-)
diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 0f1813deb527..df2d73ad85cf 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -6029,6 +6029,7 @@ static ssize_t memcg_high_async_ratio_write(struct kernfs_open_file *of,
static int wb_blkio_show(struct seq_file *m, void *v) { + struct kernfs_open_file *of = m->private; char *path; ino_t blkcg_id; struct cgroup *blkcg_cgroup; @@ -6042,12 +6043,13 @@ static int wb_blkio_show(struct seq_file *m, void *v) if (!path) return -ENOMEM;
- mutex_lock(&cgroup_mutex); + if (!cgroup_kn_lock_live(of->kn, false)) + return -ENODEV; blkcg_css = memcg->wb_blk_css; blkcg_cgroup = blkcg_css->cgroup; blkcg_id = cgroup_ino(blkcg_cgroup); cgroup_path(blkcg_cgroup, path, PATH_MAX); - mutex_unlock(&cgroup_mutex); + cgroup_kn_unlock(of->kn); seq_printf(m, "wb_blkio_path:%s\n", path); seq_printf(m, "wb_blkio_ino:%lu\n", blkcg_id); kfree(path); @@ -6073,11 +6075,12 @@ static ssize_t wb_blkio_write(struct kernfs_open_file *of, char *buf, if (ret) return ret;
- mutex_lock(&cgroup_mutex); + if (!cgroup_kn_lock_live(of->kn, false)) + return -ENODEV; root = blkcg_root_css->cgroup->root; blk_cgroup = __cgroup_get_from_id(root, cgrp_id); if (IS_ERR(blk_cgroup)) { - mutex_unlock(&cgroup_mutex); + cgroup_kn_unlock(of->kn); return -EINVAL; } blkcg_css = cgroup_tryget_css(blk_cgroup, &io_cgrp_subsys); @@ -6088,7 +6091,7 @@ static ssize_t wb_blkio_write(struct kernfs_open_file *of, char *buf,
out_unlock: cgroup_put(blk_cgroup); - mutex_unlock(&cgroup_mutex); + cgroup_kn_unlock(of->kn);
return ret < 0 ? ret : nbytes; }