Messages in this thread | | | Date | Tue, 28 Aug 2012 23:38:27 +0300 | From | Alexey Dobriyan <> | Subject | Re: [PATCH] fs/proc: Move kfree outside pde_unload_lock |
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On Wed, Aug 22, 2012 at 11:42:58PM +0200, Eric Dumazet wrote: > On Wed, 2012-08-22 at 20:28 +0200, Eric Dumazet wrote: > > > > > Thats interesting, but if you really want this to fly, one RCU > > conversion would be much better ;) > > > > pde_users would be an atomic_t and you would avoid the spinlock > > contention. > > Here is what I had in mind, I would be interested to know how it helps a 512 core machine ;)
Nothing can stop RCU!
After running "modprobe;rmmod" in a loop and "cat" in another loop for a while rmmod got stuck in D-state inside remove_proc_entry() with trace amounts of CPU time being consumed.
It didn't oopsed, though.
> --- a/include/linux/proc_fs.h > +++ b/include/linux/proc_fs.h > @@ -64,16 +64,13 @@ struct proc_dir_entry { > * If you're allocating ->proc_fops dynamically, save a pointer > * somewhere. > */ > - const struct file_operations *proc_fops; > + const struct file_operations __rcu *proc_fops; > struct proc_dir_entry *next, *parent, *subdir; > void *data; > read_proc_t *read_proc; > write_proc_t *write_proc; > atomic_t count; /* use count */ > - int pde_users; /* number of callers into module in progress */ > - struct completion *pde_unload_completion; > - struct list_head pde_openers; /* who did ->open, but not ->release */ > - spinlock_t pde_unload_lock; /* proc_fops checks and pde_users bumps */ > + atomic_t pde_users; /* number of callers into module in progress */
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