The patch titled
vmscan: cull non-reclaimable pages in fault path
has been removed from the -mm tree. Its filename was
vmscan-cull-non-reclaimable-pages-in-fault-path.patch
This patch was dropped because an updated version will be merged
The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
------------------------------------------------------
Subject: vmscan: cull non-reclaimable pages in fault path
From: Lee Schermerhorn <lee.schermerhorn@xxxxxx>
"Optional" part of "noreclaim infrastructure"
In the fault paths that install new anonymous pages, check whether the
page is reclaimable or not using lru_cache_add_active_or_noreclaim(). If
the page is reclaimable, just add it to the active lru list [via the
pagevec cache], else add it to the noreclaim list.
This "proactive" culling in the fault path mimics the handling of mlocked
pages in Nick Piggin's series to keep mlocked pages off the lru lists.
Notes:
1) This patch is optional--e.g., if one is concerned about the
additional test in the fault path. We can defer the moving of
nonreclaimable pages until when vmscan [shrink_*_list()] encounters
them. Vmscan will only need to handle such pages once.
2) The 'vma' argument to page_reclaimable() is require to notice that
we're faulting a page into an mlock()ed vma w/o having to scan the
page's rmap in the fault path. Culling mlock()ed anon pages is
currently the only reason for this patch.
3) We can't cull swap pages in read_swap_cache_async() because the vma
argument doesn't necessarily correspond to the swap cache offset passed
in by swapin_readahead(). This could [did!] result in mlocking pages
in non-VM_LOCKED vmas if [when] we tried to cull in this path.
4) Move set_pte_at() to after where we add page to lru to keep it
hidden from other tasks that might walk the page table. We already do
it in this order in do_anonymous() page. And, these are COW'd anon
pages. Is this safe?
Signed-off-by: Lee Schermerhorn <lee.schermerhorn@xxxxxx>
Signed-off-by: Rik van Riel <riel@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/swap.h | 2 ++
mm/memory.c | 20 ++++++++++++--------
mm/swap.c | 21 +++++++++++++++++++++
3 files changed, 35 insertions(+), 8 deletions(-)
diff -puN include/linux/swap.h~vmscan-cull-non-reclaimable-pages-in-fault-path include/linux/swap.h
--- a/include/linux/swap.h~vmscan-cull-non-reclaimable-pages-in-fault-path
+++ a/include/linux/swap.h
@@ -173,6 +173,8 @@ extern unsigned int nr_free_pagecache_pa
/* linux/mm/swap.c */
extern void __lru_cache_add(struct page *, enum lru_list lru);
extern void lru_cache_add_lru(struct page *, enum lru_list lru);
+extern void lru_cache_add_active_or_noreclaim(struct page *,
+ struct vm_area_struct *);
extern void activate_page(struct page *);
extern void mark_page_accessed(struct page *);
extern void lru_add_drain(void);
diff -puN mm/memory.c~vmscan-cull-non-reclaimable-pages-in-fault-path mm/memory.c
--- a/mm/memory.c~vmscan-cull-non-reclaimable-pages-in-fault-path
+++ a/mm/memory.c
@@ -1813,12 +1813,15 @@ gotten:
* thread doing COW.
*/
ptep_clear_flush(vma, address, page_table);
- set_pte_at(mm, address, page_table, entry);
- update_mmu_cache(vma, address, entry);
+
SetPageSwapBacked(new_page);
- lru_cache_add_active_anon(new_page);
+ lru_cache_add_active_or_noreclaim(new_page, vma);
page_add_new_anon_rmap(new_page, vma, address);
+//TODO: is this safe? do_anonymous_page() does it this way.
+ set_pte_at(mm, address, page_table, entry);
+ update_mmu_cache(vma, address, entry);
+
/* Free the old page.. */
new_page = old_page;
ret |= VM_FAULT_WRITE;
@@ -2285,7 +2288,7 @@ static int do_anonymous_page(struct mm_s
goto release;
inc_mm_counter(mm, anon_rss);
SetPageSwapBacked(page);
- lru_cache_add_active_anon(page);
+ lru_cache_add_active_or_noreclaim(page, vma);
page_add_new_anon_rmap(page, vma, address);
set_pte_at(mm, address, page_table, entry);
@@ -2429,12 +2432,11 @@ static int __do_fault(struct mm_struct *
entry = mk_pte(page, vma->vm_page_prot);
if (flags & FAULT_FLAG_WRITE)
entry = maybe_mkwrite(pte_mkdirty(entry), vma);
- set_pte_at(mm, address, page_table, entry);
if (anon) {
- inc_mm_counter(mm, anon_rss);
+ inc_mm_counter(mm, anon_rss);
SetPageSwapBacked(page);
- lru_cache_add_active_anon(page);
- page_add_new_anon_rmap(page, vma, address);
+ lru_cache_add_active_or_noreclaim(page, vma);
+ page_add_new_anon_rmap(page, vma, address);
} else {
inc_mm_counter(mm, file_rss);
page_add_file_rmap(page);
@@ -2443,6 +2445,8 @@ static int __do_fault(struct mm_struct *
get_page(dirty_page);
}
}
+//TODO: is this safe? do_anonymous_page() does it this way.
+ set_pte_at(mm, address, page_table, entry);
/* no need to invalidate: a not-present page won't be cached */
update_mmu_cache(vma, address, entry);
diff -puN mm/swap.c~vmscan-cull-non-reclaimable-pages-in-fault-path mm/swap.c
--- a/mm/swap.c~vmscan-cull-non-reclaimable-pages-in-fault-path
+++ a/mm/swap.c
@@ -31,6 +31,8 @@
#include <linux/backing-dev.h>
#include <linux/memcontrol.h>
+#include "internal.h"
+
/* How many pages do we try to swap or page in/out together? */
int page_cluster;
@@ -273,6 +275,25 @@ void add_page_to_noreclaim_list(struct p
spin_unlock_irq(&zone->lru_lock);
}
+/**
+ * lru_cache_add_active_or_noreclaim
+ * @page: the page to be added to LRU
+ * @vma: vma in which page is mapped for determining reclaimability
+ *
+ * place @page on active or noreclaim LRU list, depending on
+ * page_reclaimable(). Note that if the page is not reclaimable,
+ * it goes directly back onto it's zone's noreclaim list. It does
+ * NOT use a per cpu pagevec.
+ */
+void lru_cache_add_active_or_noreclaim(struct page *page,
+ struct vm_area_struct *vma)
+{
+ if (page_reclaimable(page, vma))
+ lru_cache_add_lru(page, LRU_ACTIVE + page_file_cache(page));
+ else
+ add_page_to_noreclaim_list(page);
+}
+
/*
* Drain pages out of the cpu's pagevecs.
* Either "cpu" is the current CPU, and preemption has already been
_
Patches currently in -mm which might be from lee.schermerhorn@xxxxxx are
page-allocator-inlnie-some-__alloc_pages-wrappers.patch
page-allocator-inlnie-some-__alloc_pages-wrappers-fix.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
mm-only-vmscan-noreclaim-lru-scan-sysctl-fix.patch
vmscan-mlocked-pages-count-attempts-to-free-mlocked-page.patch
vmscan-noreclaim-lru-and-mlocked-pages-documentation.patch
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