running get_user_pages() from kernel thread

From: Izik Eidus
Date: Tue Jun 16 2009 - 14:05:41 EST


Hey,

ksm is running from its kernel thread context get_user_pages(), but look like it isnt safe to do get_user_pages() from kernel thread:
get_user_pages may lead into do_swap_page() that may lead into calling grab_swap_token()

Now grab_swap_token() will do:
current_interval = global_faults - current->mm->... (here is the bug... (kernel thread doesnt have mm strcture)

So the question is: is this thing is by desgin? (that kernel thread cant call get_user_pages???), should i use something like switch_mm()??

Thanks.


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