The patch titled
vmscan: free swap space on swap-in/activation
has been added to the -mm tree. Its filename is
vmscan-free-swap-space-on-swap-in-activation.patch
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------------------------------------------------------
Subject: vmscan: free swap space on swap-in/activation
From: Rik van Riel <riel@xxxxxxxxxx>
Free swap cache entries when swapping in pages if vm_swap_full()
[swap space > 1/2 used]. Uses new pagevec to reduce pressure
on locks.
Signed-off-by: Rik van Riel <riel@xxxxxxxxxx>
Signed-off-by: Lee Schermerhorn <Lee.Schermerhorn@xxxxxx>
Signed-off-by: MinChan Kim <minchan.kim@xxxxxxxxx>
---
Index: linux-2.6.26-rc2-mm1/mm/vmscan.c
===================================================================
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/pagevec.h | 1 +
include/linux/swap.h | 6 ++++++
mm/swap.c | 18 ++++++++++++++++++
mm/swapfile.c | 25 ++++++++++++++++++++++---
mm/vmscan.c | 7 +++++++
5 files changed, 54 insertions(+), 3 deletions(-)
diff -puN include/linux/pagevec.h~free-swap-space-on-swap-in-activation include/linux/pagevec.h
--- a/include/linux/pagevec.h~free-swap-space-on-swap-in-activation
+++ a/include/linux/pagevec.h
@@ -25,6 +25,7 @@ void __pagevec_release_nonlru(struct pag
void __pagevec_free(struct pagevec *pvec);
void ____pagevec_lru_add(struct pagevec *pvec, enum lru_list lru);
void pagevec_strip(struct pagevec *pvec);
+void pagevec_swap_free(struct pagevec *pvec);
unsigned pagevec_lookup(struct pagevec *pvec, struct address_space *mapping,
pgoff_t start, unsigned nr_pages);
unsigned pagevec_lookup_tag(struct pagevec *pvec,
diff -puN include/linux/swap.h~free-swap-space-on-swap-in-activation include/linux/swap.h
--- a/include/linux/swap.h~free-swap-space-on-swap-in-activation
+++ a/include/linux/swap.h
@@ -266,6 +266,7 @@ extern sector_t swapdev_block(int, pgoff
extern struct swap_info_struct *get_swap_info_struct(unsigned);
extern int can_share_swap_page(struct page *);
extern int remove_exclusive_swap_page(struct page *);
+extern int remove_exclusive_swap_page_ref(struct page *);
struct backing_dev_info;
extern spinlock_t swap_lock;
@@ -356,6 +357,11 @@ static inline int remove_exclusive_swap_
return 0;
}
+static inline int remove_exclusive_swap_page_ref(struct page *page)
+{
+ return 0;
+}
+
static inline swp_entry_t get_swap_page(void)
{
swp_entry_t entry;
diff -puN mm/swap.c~free-swap-space-on-swap-in-activation mm/swap.c
--- a/mm/swap.c~free-swap-space-on-swap-in-activation
+++ a/mm/swap.c
@@ -443,6 +443,24 @@ void pagevec_strip(struct pagevec *pvec)
}
}
+/*
+ * Try to free swap space from the pages in a pagevec
+ */
+void pagevec_swap_free(struct pagevec *pvec)
+{
+ int i;
+
+ for (i = 0; i < pagevec_count(pvec); i++) {
+ struct page *page = pvec->pages[i];
+
+ if (PageSwapCache(page) && !TestSetPageLocked(page)) {
+ if (PageSwapCache(page))
+ remove_exclusive_swap_page_ref(page);
+ unlock_page(page);
+ }
+ }
+}
+
/**
* pagevec_lookup - gang pagecache lookup
* @pvec: Where the resulting pages are placed
diff -puN mm/swapfile.c~free-swap-space-on-swap-in-activation mm/swapfile.c
--- a/mm/swapfile.c~free-swap-space-on-swap-in-activation
+++ a/mm/swapfile.c
@@ -343,7 +343,7 @@ int can_share_swap_page(struct page *pag
* Work out if there are any other processes sharing this
* swap cache page. Free it if you can. Return success.
*/
-int remove_exclusive_swap_page(struct page *page)
+static int remove_exclusive_swap_page_count(struct page *page, int count)
{
int retval;
struct swap_info_struct * p;
@@ -356,7 +356,7 @@ int remove_exclusive_swap_page(struct pa
return 0;
if (PageWriteback(page))
return 0;
- if (page_count(page) != 2) /* 2: us + cache */
+ if (page_count(page) != count) /* us + cache + ptes */
return 0;
entry.val = page_private(page);
@@ -369,7 +369,7 @@ int remove_exclusive_swap_page(struct pa
if (p->swap_map[swp_offset(entry)] == 1) {
/* Recheck the page count with the swapcache lock held.. */
spin_lock_irq(&swapper_space.tree_lock);
- if ((page_count(page) == 2) && !PageWriteback(page)) {
+ if ((page_count(page) == count) && !PageWriteback(page)) {
__delete_from_swap_cache(page);
SetPageDirty(page);
retval = 1;
@@ -387,6 +387,25 @@ int remove_exclusive_swap_page(struct pa
}
/*
+ * Most of the time the page should have two references: one for the
+ * process and one for the swap cache.
+ */
+int remove_exclusive_swap_page(struct page *page)
+{
+ return remove_exclusive_swap_page_count(page, 2);
+}
+
+/*
+ * The pageout code holds an extra reference to the page. That raises
+ * the reference count to test for to 2 for a page that is only in the
+ * swap cache plus 1 for each process that maps the page.
+ */
+int remove_exclusive_swap_page_ref(struct page *page)
+{
+ return remove_exclusive_swap_page_count(page, 2 + page_mapcount(page));
+}
+
+/*
* Free the swap entry like above, but also try to
* free the page cache entry if it is the last user.
*/
diff -puN mm/vmscan.c~free-swap-space-on-swap-in-activation mm/vmscan.c
--- a/mm/vmscan.c~free-swap-space-on-swap-in-activation
+++ a/mm/vmscan.c
@@ -637,6 +637,9 @@ free_it:
continue;
activate_locked:
+ /* Not a candidate for swapping, so reclaim swap space. */
+ if (PageSwapCache(page) && vm_swap_full())
+ remove_exclusive_swap_page_ref(page);
SetPageActive(page);
pgactivate++;
keep_locked:
@@ -1221,6 +1224,8 @@ static void shrink_active_list(unsigned
__mod_zone_page_state(zone, NR_ACTIVE, pgmoved);
pgmoved = 0;
spin_unlock_irq(&zone->lru_lock);
+ if (vm_swap_full())
+ pagevec_swap_free(&pvec);
__pagevec_release(&pvec);
spin_lock_irq(&zone->lru_lock);
}
@@ -1230,6 +1235,8 @@ static void shrink_active_list(unsigned
__count_zone_vm_events(PGREFILL, zone, pgscanned);
__count_vm_events(PGDEACTIVATE, pgdeactivate);
spin_unlock_irq(&zone->lru_lock);
+ if (vm_swap_full())
+ pagevec_swap_free(&pvec);
pagevec_release(&pvec);
}
_
Patches currently in -mm which might be from riel@xxxxxxxxxx are
ntp-let-update_persistent_clock-sleep.patch
access_process_vm-device-memory-infrastructure.patch
access_process_vm-device-memory-infrastructure-fix.patch
use-generic_access_phys-for-dev-mem-mappings.patch
use-generic_access_phys-for-dev-mem-mappings-fix.patch
use-generic_access_phys-for-pci-mmap-on-x86.patch
powerpc-ioremap_prot.patch
spufs-use-the-new-vm_ops-access.patch
spufs-use-the-new-vm_ops-access-fix.patch
page-flags-record-page-flag-overlays-explicitly.patch
page-flags-record-page-flag-overlays-explicitly-xen.patch
slub-record-page-flag-overlays-explicitly.patch
slob-record-page-flag-overlays-explicitly.patch
vmscan-give-referenced-active-and-unmapped-pages-a-second-trip-around-the-lru.patch
idr-change-the-idr-structure.patch
idr-rename-some-of-the-idr-apis-internal-routines.patch
idr-fix-a-printk-call.patch
idr-error-checking-factorization.patch
idr-make-idr_get_new-rcu-safe.patch
idr-make-idr_get_new-rcu-safe-fix.patch
idr-make-idr_find-rcu-safe.patch
idr-make-idr_remove-rcu-safe.patch
ipc-call-idr_find-without-locking-in-ipc_lock.patch
ipc-get-rid-of-ipc_lock_down.patch
vmscan-move-isolate_lru_page-to-vmscanc.patch
vmscan-use-an-indexed-array-for-lru-variables.patch
vmscan-use-an-array-for-the-lru-pagevecs.patch
vmscan-free-swap-space-on-swap-in-activation.patch
vmscan-define-page_file_cache-function.patch
vmscan-split-lru-lists-into-anon-file-sets.patch
vmscan-second-chance-replacement-for-anonymous-pages.patch
vmscan-add-some-sanity-checks-to-get_scan_ratio.patch
vmscan-fix-pagecache-reclaim-referenced-bit-check.patch
vmscan-add-newly-swapped-in-pages-to-the-inactive-list.patch
vmscan-more-aggressively-use-lumpy-reclaim.patch
vmscan-pageflag-helpers-for-configed-out-flags.patch
vmscan-noreclaim-lru-infrastructure.patch
vmscan-noreclaim-lru-page-statistics.patch
vmscan-ramfs-and-ram-disk-pages-are-non-reclaimable.patch
vmscan-shm_locked-pages-are-non-reclaimable.patch
vmscan-mlocked-pages-are-non-reclaimable.patch
vmscan-downgrade-mmap-sem-while-populating-mlocked-regions.patch
vmscan-handle-mlocked-pages-during-map-remap-unmap.patch
vmscan-mlocked-pages-statistics.patch
vmscan-cull-non-reclaimable-pages-in-fault-path.patch
vmscan-noreclaim-and-mlocked-pages-vm-events.patch
mm-only-vmscan-noreclaim-lru-scan-sysctl.patch
vmscan-mlocked-pages-count-attempts-to-free-mlocked-page.patch
vmscan-noreclaim-lru-and-mlocked-pages-documentation.patch
make-mm-rmapc-anon_vma_cachep-static.patch
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