Messages in this thread | | | Subject | Re: INFO: HARDIRQ-safe -> HARDIRQ-unsafe lock order detected for kmemleak_lock | From | Catalin Marinas <> | Date | Wed, 02 Sep 2009 11:54:08 +0100 |
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Hi Eric,
On Tue, 2009-09-01 at 16:55 -0400, Eric Paris wrote: > I wrote a multithreaded inotify syscall pounder intended to create > files, destroy files, create watches, and destroy watches with the > maximum number of races possible. Instead after letting it run a while > I came upon this! And then my system started to crash in all sorts of > fun and glorious ways (kmem_cache_alloc bugs/panics/whatever) > > -Eric > > [ 2235.913737] ====================================================== > [ 2235.914084] [ INFO: HARDIRQ-safe -> HARDIRQ-unsafe lock order detected ] > [ 2235.914084] 2.6.31-rc8-next-20090901 #64 > [ 2235.914084] ------------------------------------------------------ > [ 2235.914084] syscall_thrash/2516 [HC0[0]:SC0[0]:HE0:SE1] is trying to acquire: > [ 2235.914084] (kthread_create_lock){+.+...}, at: [<ffffffff81091543>] kthread_create+0x73/0x180 > [ 2235.914084] > [ 2235.914084] and this task is already holding: > [ 2235.914084] (kmemleak_lock){..----}, at: [<ffffffff81152611>] create_object+0x161/0x2e0 > [ 2235.914084] which would create a new lock dependency: > [ 2235.914084] (kmemleak_lock){..----} -> (kthread_create_lock){+.+...}
Are there other messages from kmemleak printed before that? It looks to me like kmemleak got an exceptional situation (not being able to allocate memory or inserting a pointer into the prio search tree) and it disabled itself. When disabling, it starts a clean-up thread and AFAICT that's the only condition when kmemleak_lock -> kthread_create_lock dependency would be created.
I'm not sure whether disabling interrupts around kthread_run in kmemleak_cleanup() would solve the problem. Otherwise, maybe the kmemleak clean-up thread should take a different form or just a thread waiting for a clean-up event (it currently acquires a mutex and cannot be used in interrupt context).
Thanks.
-- Catalin
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