Messages in this thread | | | Date | Thu, 14 Nov 2019 09:34:10 -0500 | From | Steven Rostedt <> | Subject | Re: [PATCH] debugfs: fix potential infinite loop in debugfs_remove_recursive |
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On Thu, 14 Nov 2019 14:59:04 +0800 "yukuai (C)" <yukuai3@huawei.com> wrote:
> > Have you tried this patch with lockdep enabled and tried to hit this > > code path? > >
> > > You are right, I get the results with lockdep enabled:
That was what I was afraid of :-(
> [ 64.314748] ============================================ > [ 64.315568] WARNING: possible recursive locking detected > [ 64.316549] 5.4.0-rc7-dirty #5 Tainted: G O > [ 64.317398] -------------------------------------------- > [ 64.318230] rmmod/2607 is trying to acquire lock:
> > The warning will disappeare by adding > lockdep_set_novalidate_class(&child->d_lock) before calling > simple_empty(child). But I'm not sure It's the right modfication.
I'm wondering if we should add a simple_empty_unlocked() that does simple_empty() without taking the lock, to allow us to call spin_lock_nested() on the child. Of course, I don't know how much nesting we allow as it calls the nesting too.
This looks to be something that the vfs folks need to look at.
-- Steve
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