[PATCH] SwapMig: add_to_swap() avoid atomic allocations

Add gfp_mask to add_to_swap

add_to_swap does allocations with GFP_ATOMIC in order not to interfere with
swapping.  During migration we may have use add_to_swap extensively which may
lead to out of memory errors.

This patch makes add_to_swap take a parameter that specifies the gfp mask.
The page migration code can then make add_to_swap use GFP_KERNEL.

Signed-off-by: Hirokazu Takahashi <taka@valinux.co.jp>
Signed-off-by: Dave Hansen <haveblue@us.ibm.com>
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

2 files changed, 4 insertions, 4 deletions

diff --git a/mm/swap_state.c b/mm/swap_state.c
index fc2aecb70a95..7b09ac503fec 100644
--- a/mm/swap_state.c
+++ b/mm/swap_state.c
@@ -141,7 +141,7 @@ void __delete_from_swap_cache(struct page *page)
  * Allocate swap space for the page and add the page to the
  * swap cache.  Caller needs to hold the page lock. 
  */
-int add_to_swap(struct page * page)
+int add_to_swap(struct page * page, gfp_t gfp_mask)
 {
         swp_entry_t entry;
         int err;
@@ -166,7 +166,7 @@ int add_to_swap(struct page * page)
                  * Add it to the swap cache and mark it dirty
                  */
                 err = __add_to_swap_cache(page, entry,
-                                GFP_ATOMIC|__GFP_NOMEMALLOC|__GFP_NOWARN);
+                                gfp_mask|__GFP_NOMEMALLOC|__GFP_NOWARN);
 
                 switch (err) {
                 case 0:                         /* Success */
diff --git a/mm/vmscan.c b/mm/vmscan.c
index daed4a73b761..5393b093a87b 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -458,7 +458,7 @@ static int shrink_list(struct list_head *page_list, struct scan_control *sc)
                  * Try to allocate it some swap space here.
                  */
                 if (PageAnon(page) && !PageSwapCache(page)) {
-                        if (!add_to_swap(page))
+                        if (!add_to_swap(page, GFP_ATOMIC))
                                 goto activate_locked;
                 }
 #endif /* CONFIG_SWAP */
@@ -715,7 +715,7 @@ redo:
                 }
 
                 if (PageAnon(page) && !PageSwapCache(page)) {
-                        if (!add_to_swap(page)) {
+                        if (!add_to_swap(page, GFP_KERNEL)) {
                                 unlock_page(page);
                                 list_move(&page->lru, &failed);
                                 nr_failed++;