Re: [PATCH resend] fs/proc: Move kfree outside pde_unload_lock

From: Nathan Zimmer
Date: Fri Apr 05 2013 - 16:56:12 EST


On 04/05/2013 12:36 PM, Al Viro wrote:
On Fri, Apr 05, 2013 at 12:05:26PM -0500, Nathan Zimmer wrote:
On 04/04/2013 03:44 PM, Al Viro wrote:
On Thu, Apr 04, 2013 at 12:12:05PM -0500, Nathan Zimmer wrote:

Ok I am cloning the tree now.
It does look like the patches would conflict.
I'll run some tests and take a deeper look.
FWIW, I've just pushed there a tentative patch that switches to hopefully
saner locking (head should be at cb673c115c1f99d3480471ca5d8cb3f89a1e3bee).
Is that more or less what you want wrt spinlock contention?

One note: for any given pde_opener, close_pdeo() can be called at most
by two threads - final fput() and remove_proc_entry() resp. I think
the use of completion + flag is safe there; pde->pde_unload_lock
should serialize the critical areas.
Something isn't quite right. I keep getting hung during boot.
dracut: Mounted root filesystem /dev/sda8
dracut: Switching root

I'll try to get some more info on a smaller box.
Umm... Try to add WARN_ON(1) in entry_rundown(), just to see what's
getting hit (don't bother with entry name, stack trace will be enough).
That didn't produce anything. I'll run some bisections over the weekend and see what I can sort out.
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