Messages in this thread | | | Date | Wed, 13 May 2009 11:56:26 -0700 | From | Andrew Morton <> | Subject | Re: [BUGFIX][PATCH] memcg: fix deadlock between lock_page_cgroup and mapping tree_lock |
| |
On Wed, 13 May 2009 13:30:31 +0900 Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> wrote:
> mapping->tree_lock can be aquired from interrupt context. > Then, following dead lock can occur. > > Assume "A" as a page. > > CPU0: > lock_page_cgroup(A) > interrupted > -> take mapping->tree_lock. > CPU1: > take mapping->tree_lock > -> lock_page_cgroup(A)
And we didn't find out about this because lock_page_cgroup() uses bit_spin_lock(), and lockdep doesn't handle bit_spin_lock().
It would perhaps be useful if one of you guys were to add a spinlock to struct page, convert lock_page_cgroup() to use that spinlock then run a full set of tests under lockdep, see if it can shake out any other bugs.
| |