expand_stack(), it is hard to come up with a destructive scenario without
having the vmlist protection in this case.
-The page_table_lock nests with the inode i_shared_sem and the kmem cache
+The page_table_lock nests with the inode i_mmap_lock and the kmem cache
c_spinlock spinlocks. This is okay, since the kmem code asks for pages after
dropping c_spinlock. The page_table_lock also nests with pagecache_lock and
pagemap_lru_lock spinlocks, and no code asks for memory with these locks
vmtruncate) does not lose sending ipi's to cloned threads that might
be spawned underneath it and go to user mode to drag in pte's into tlbs.
-swap_list_lock/swap_device_lock
--------------------------------
+swap_lock
+--------------
The swap devices are chained in priority order from the "swap_list" header.
The "swap_list" is used for the round-robin swaphandle allocation strategy.
The #free swaphandles is maintained in "nr_swap_pages". These two together
-are protected by the swap_list_lock.
+are protected by the swap_lock.
-The swap_device_lock, which is per swap device, protects the reference
-counts on the corresponding swaphandles, maintained in the "swap_map"
-array, and the "highest_bit" and "lowest_bit" fields.
+The swap_lock also protects all the device reference counts on the
+corresponding swaphandles, maintained in the "swap_map" array, and the
+"highest_bit" and "lowest_bit" fields.
-Both of these are spinlocks, and are never acquired from intr level. The
-locking hierarchy is swap_list_lock -> swap_device_lock.
+The swap_lock is a spinlock, and is never acquired from intr level.
To prevent races between swap space deletion or async readahead swapins
deciding whether a swap handle is being used, ie worthy of being read in
git://git.onelab.eu / linux-2.6.git / blobdiff