suse man page for __lock_page

__LOCK_PAGE(9)						    Memory Management in Linux						    __LOCK_PAGE(9)

NAME
       __lock_page - get a lock on the page, assuming we need to sleep to get it

SYNOPSIS
       void __lock_page(struct page * page);

ARGUMENTS
       page
	   the page to lock

DESCRIPTION
       Ugly. Running sync_page in state TASK_UNINTERRUPTIBLE is scary. If some random driver's requestfn sets TASK_RUNNING, we could busywait.
       However chances are that on the second loop, the block layer's plug list is empty, so sync_page will then return in state
       TASK_UNINTERRUPTIBLE.

COPYRIGHT
Kernel Hackers Manual 2.6.					     July 2010							    __LOCK_PAGE(9)