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| author | Thomas Gleixner <tglx@mtd.linutronix.de> | 2005-11-06 15:36:37 +0100 |
|---|---|---|
| committer | Thomas Gleixner <tglx@mtd.linutronix.de> | 2005-11-06 15:36:37 +0100 |
| commit | 2fc2991175bf77395e6b15fe6b2304d3bf72da40 (patch) | |
| tree | b0ff38c09240e7c00e1577d447ebe89143d752dc /Documentation/vm/locking | |
| parent | 8b491d750885ebe8e7d385ce4186c85957d67123 (diff) | |
| parent | 7015faa7df829876a0f931cd18aa6d7c24a1b581 (diff) | |
Merge branch 'master' of /home/tglx/work/mtd/git/linux-2.6.git/
Diffstat (limited to 'Documentation/vm/locking')
| -rw-r--r-- | Documentation/vm/locking | 15 |
1 files changed, 7 insertions, 8 deletions
diff --git a/Documentation/vm/locking b/Documentation/vm/locking index c3ef09ae3bb1..f366fa956179 100644 --- a/Documentation/vm/locking +++ b/Documentation/vm/locking @@ -83,19 +83,18 @@ single address space optimization, so that the zap_page_range (from 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 |