diff options
author | Muchun Song <songmuchun@bytedance.com> | 2021-04-02 17:11:45 +0800 |
---|---|---|
committer | Jan Kara <jack@suse.cz> | 2021-06-28 18:35:02 +0200 |
commit | 8b0ed8443ae6458786580d36b7d5f8125535c5d4 (patch) | |
tree | 4cb9fc32fd24cb332daeb2cbd6d0715d43a06828 /arch/ia64/kernel/syscalls | |
parent | ce1b06c5f5e7fd2af8bc89323d9eb3102d8e3fe2 (diff) |
writeback: fix obtain a reference to a freeing memcg css
The caller of wb_get_create() should pin the memcg, because
wb_get_create() relies on this guarantee. The rcu read lock
only can guarantee that the memcg css returned by css_from_id()
cannot be released, but the reference of the memcg can be zero.
rcu_read_lock()
memcg_css = css_from_id()
wb_get_create(memcg_css)
cgwb_create(memcg_css)
// css_get can change the ref counter from 0 back to 1
css_get(memcg_css)
rcu_read_unlock()
Fix it by holding a reference to the css before calling
wb_get_create(). This is not a problem I encountered in the
real world. Just the result of a code review.
Fixes: 682aa8e1a6a1 ("writeback: implement unlocked_inode_to_wb transaction and use it for stat updates")
Link: https://lore.kernel.org/r/20210402091145.80635-1-songmuchun@bytedance.com
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jan Kara <jack@suse.cz>
Diffstat (limited to 'arch/ia64/kernel/syscalls')
0 files changed, 0 insertions, 0 deletions