X-Git-Url: https://git.openpandora.org/cgi-bin/gitweb.cgi?p=pandora-kernel.git;a=blobdiff_plain;f=mm%2Fswap_state.c;h=e4f41013a6c04ca59c8eda6f61df4b4e10027b7e;hp=46680461785bef647c3618bc7d493d1909aea80f;hb=4cecd7e369e1b252db1d64451462221b362eed1c;hpb=b759b3ac9aee3afb01c21b603970ebb200c8048e

diff --git a/mm/swap_state.c b/mm/swap_state.c
index 46680461785b..e4f41013a6c0 100644
--- a/mm/swap_state.c
+++ b/mm/swap_state.c
@@ -6,7 +6,6 @@
  *
  *  Rewritten to use page cache, (C) 1998 Stephen Tweedie
  */
-#include <linux/module.h>
 #include <linux/mm.h>
 #include <linux/gfp.h>
 #include <linux/kernel_stat.h>
@@ -28,7 +27,7 @@
  */
 static const struct address_space_operations swap_aops = {
 	.writepage	= swap_writepage,
-	.set_page_dirty	= __set_page_dirty_nobuffers,
+	.set_page_dirty	= __set_page_dirty_no_writeback,
 	.migratepage	= migrate_page,
 };
 
@@ -39,6 +38,7 @@ static struct backing_dev_info swap_backing_dev_info = {
 
 struct address_space swapper_space = {
 	.page_tree	= RADIX_TREE_INIT(GFP_ATOMIC|__GFP_NOWARN),
+	.i_mmap_writable = ATOMIC_INIT(0),
 	.tree_lock	= __SPIN_LOCK_UNLOCKED(swapper_space.tree_lock),
 	.a_ops		= &swap_aops,
 	.i_mmap_nonlinear = LIST_HEAD_INIT(swapper_space.i_mmap_nonlinear),
@@ -315,8 +315,24 @@ struct page *read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask,
 		 * Swap entry may have been freed since our caller observed it.
 		 */
 		err = swapcache_prepare(entry);
-		if (err == -EEXIST) {	/* seems racy */
+		if (err == -EEXIST) {
 			radix_tree_preload_end();
+			/*
+			 * We might race against get_swap_page() and stumble
+			 * across a SWAP_HAS_CACHE swap_map entry whose page
+			 * has not been brought into the swapcache yet, while
+			 * the other end is scheduled away waiting on discard
+			 * I/O completion at scan_swap_map().
+			 *
+			 * In order to avoid turning this transitory state
+			 * into a permanent loop around this -EEXIST case
+			 * if !CONFIG_PREEMPT and the I/O completion happens
+			 * to be waiting on the CPU waitqueue where we are now
+			 * busy looping, we just conditionally invoke the
+			 * scheduler here, if there are some more important
+			 * tasks to run.
+			 */
+			cond_resched();
 			continue;
 		}
 		if (err) {		/* swp entry is obsolete ? */