[PATCH] temporarily disable swap token on memory pressure
Some users (hi Zwane) have seen a problem when running a workload that
eats nearly all of physical memory - th system does an OOM kill, even
when there is still a lot of swap free.
The problem appears to be a very big task that is holding the swap
token, and the VM has a very hard time finding any other page in the
system that is swappable.
Instead of ignoring the swap token when sc->priority reaches 0, we could
simply take the swap token away from the memory hog and make sure we
don't give it back to the memory hog for a few seconds.
This patch resolves the problem Zwane ran into.
Signed-off-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/include/linux/rmap.h b/include/linux/rmap.h
index 35b30e6..33261f1 100644
--- a/include/linux/rmap.h
+++ b/include/linux/rmap.h
@@ -89,7 +89,7 @@
/*
* Called from mm/vmscan.c to handle paging out
*/
-int page_referenced(struct page *, int is_locked, int ignore_token);
+int page_referenced(struct page *, int is_locked);
int try_to_unmap(struct page *);
/*
@@ -109,7 +109,7 @@
#define anon_vma_prepare(vma) (0)
#define anon_vma_link(vma) do {} while (0)
-#define page_referenced(page,l,i) TestClearPageReferenced(page)
+#define page_referenced(page,l) TestClearPageReferenced(page)
#define try_to_unmap(page) SWAP_FAIL
#endif /* CONFIG_MMU */
diff --git a/include/linux/swap.h b/include/linux/swap.h
index 20c9756..508668f 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -239,6 +239,11 @@
__put_swap_token(mm);
}
+static inline void disable_swap_token(void)
+{
+ put_swap_token(swap_token_mm);
+}
+
#else /* CONFIG_SWAP */
#define total_swap_pages 0
@@ -283,6 +288,7 @@
#define put_swap_token(x) do { } while(0)
#define grab_swap_token() do { } while(0)
#define has_swap_token(x) 0
+#define disable_swap_token() do { } while(0)
#endif /* CONFIG_SWAP */
#endif /* __KERNEL__*/
diff --git a/mm/rmap.c b/mm/rmap.c
index 6389cda..491ac35 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -290,7 +290,7 @@
* repeatedly from either page_referenced_anon or page_referenced_file.
*/
static int page_referenced_one(struct page *page,
- struct vm_area_struct *vma, unsigned int *mapcount, int ignore_token)
+ struct vm_area_struct *vma, unsigned int *mapcount)
{
struct mm_struct *mm = vma->vm_mm;
unsigned long address;
@@ -311,7 +311,7 @@
/* Pretend the page is referenced if the task has the
swap token and is in the middle of a page fault. */
- if (mm != current->mm && !ignore_token && has_swap_token(mm) &&
+ if (mm != current->mm && has_swap_token(mm) &&
rwsem_is_locked(&mm->mmap_sem))
referenced++;
@@ -321,7 +321,7 @@
return referenced;
}
-static int page_referenced_anon(struct page *page, int ignore_token)
+static int page_referenced_anon(struct page *page)
{
unsigned int mapcount;
struct anon_vma *anon_vma;
@@ -334,8 +334,7 @@
mapcount = page_mapcount(page);
list_for_each_entry(vma, &anon_vma->head, anon_vma_node) {
- referenced += page_referenced_one(page, vma, &mapcount,
- ignore_token);
+ referenced += page_referenced_one(page, vma, &mapcount);
if (!mapcount)
break;
}
@@ -354,7 +353,7 @@
*
* This function is only called from page_referenced for object-based pages.
*/
-static int page_referenced_file(struct page *page, int ignore_token)
+static int page_referenced_file(struct page *page)
{
unsigned int mapcount;
struct address_space *mapping = page->mapping;
@@ -392,8 +391,7 @@
referenced++;
break;
}
- referenced += page_referenced_one(page, vma, &mapcount,
- ignore_token);
+ referenced += page_referenced_one(page, vma, &mapcount);
if (!mapcount)
break;
}
@@ -410,13 +408,10 @@
* Quick test_and_clear_referenced for all mappings to a page,
* returns the number of ptes which referenced the page.
*/
-int page_referenced(struct page *page, int is_locked, int ignore_token)
+int page_referenced(struct page *page, int is_locked)
{
int referenced = 0;
- if (!swap_token_default_timeout)
- ignore_token = 1;
-
if (page_test_and_clear_young(page))
referenced++;
@@ -425,15 +420,14 @@
if (page_mapped(page) && page->mapping) {
if (PageAnon(page))
- referenced += page_referenced_anon(page, ignore_token);
+ referenced += page_referenced_anon(page);
else if (is_locked)
- referenced += page_referenced_file(page, ignore_token);
+ referenced += page_referenced_file(page);
else if (TestSetPageLocked(page))
referenced++;
else {
if (page->mapping)
- referenced += page_referenced_file(page,
- ignore_token);
+ referenced += page_referenced_file(page);
unlock_page(page);
}
}
diff --git a/mm/thrash.c b/mm/thrash.c
index eff3c18..f4c560b 100644
--- a/mm/thrash.c
+++ b/mm/thrash.c
@@ -57,14 +57,17 @@
/* We have the token. Let others know we still need it. */
if (has_swap_token(current->mm)) {
current->mm->recent_pagein = 1;
+ if (unlikely(!swap_token_default_timeout))
+ disable_swap_token();
return;
}
if (time_after(jiffies, swap_token_check)) {
- /* Can't get swapout protection if we exceed our RSS limit. */
- // if (current->mm->rss > current->mm->rlimit_rss)
- // return;
+ if (!swap_token_default_timeout) {
+ swap_token_check = jiffies + SWAP_TOKEN_CHECK_INTERVAL;
+ return;
+ }
/* ... or if we recently held the token. */
if (time_before(jiffies, current->mm->swap_token_time))
@@ -95,6 +98,7 @@
{
spin_lock(&swap_token_lock);
if (likely(mm == swap_token_mm)) {
+ mm->swap_token_time = jiffies + SWAP_TOKEN_CHECK_INTERVAL;
swap_token_mm = &init_mm;
swap_token_check = jiffies;
}
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 2813054..078cf92 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -407,7 +407,7 @@
if (PageWriteback(page))
goto keep_locked;
- referenced = page_referenced(page, 1, sc->priority <= 0);
+ referenced = page_referenced(page, 1);
/* In active use or really unfreeable? Activate it. */
if (referenced && page_mapping_inuse(page))
goto activate_locked;
@@ -756,7 +756,7 @@
if (page_mapped(page)) {
if (!reclaim_mapped ||
(total_swap_pages == 0 && PageAnon(page)) ||
- page_referenced(page, 0, sc->priority <= 0)) {
+ page_referenced(page, 0)) {
list_add(&page->lru, &l_active);
continue;
}
@@ -960,6 +960,8 @@
sc.nr_reclaimed = 0;
sc.priority = priority;
sc.swap_cluster_max = SWAP_CLUSTER_MAX;
+ if (!priority)
+ disable_swap_token();
shrink_caches(zones, &sc);
shrink_slab(sc.nr_scanned, gfp_mask, lru_pages);
if (reclaim_state) {
@@ -1056,6 +1058,10 @@
int end_zone = 0; /* Inclusive. 0 = ZONE_DMA */
unsigned long lru_pages = 0;
+ /* The swap token gets in the way of swapout... */
+ if (!priority)
+ disable_swap_token();
+
all_zones_ok = 1;
if (nr_pages == 0) {
@@ -1360,6 +1366,7 @@
sc.nr_reclaimed = 0;
/* scan at the highest priority */
sc.priority = 0;
+ disable_swap_token();
if (nr_pages > SWAP_CLUSTER_MAX)
sc.swap_cluster_max = nr_pages;