#include <linux/swap.h>
#include <linux/swapops.h>
#include <linux/pagemap.h>
+#include <linux/pagevec.h>
#include <linux/mempolicy.h>
#include <linux/syscalls.h>
#include <linux/sched.h>
#include <linux/rmap.h>
#include <linux/mmzone.h>
#include <linux/hugetlb.h>
+#include <linux/memcontrol.h>
+#include <linux/mm_inline.h>
#include "internal.h"
}
}
+/*
+ * Finish munlock after successful page isolation
+ *
+ * Page must be locked. This is a wrapper for try_to_munlock()
+ * and putback_lru_page() with munlock accounting.
+ */
+static void __munlock_isolated_page(struct page *page)
+{
+ int ret = SWAP_AGAIN;
+
+ /*
+ * Optimization: if the page was mapped just once, that's our mapping
+ * and we don't need to check all the other vmas.
+ */
+ if (page_mapcount(page) > 1)
+ ret = try_to_munlock(page);
+
+ /* Did try_to_unlock() succeed or punt? */
+ if (ret != SWAP_MLOCK)
+ count_vm_event(UNEVICTABLE_PGMUNLOCKED);
+
+ putback_lru_page(page);
+}
+
+/*
+ * Accounting for page isolation fail during munlock
+ *
+ * Performs accounting when page isolation fails in munlock. There is nothing
+ * else to do because it means some other task has already removed the page
+ * from the LRU. putback_lru_page() will take care of removing the page from
+ * the unevictable list, if necessary. vmscan [page_referenced()] will move
+ * the page back to the unevictable list if some other vma has it mlocked.
+ */
+static void __munlock_isolation_failed(struct page *page)
+{
+ if (PageUnevictable(page))
+ count_vm_event(UNEVICTABLE_PGSTRANDED);
+ else
+ count_vm_event(UNEVICTABLE_PGMUNLOCKED);
+}
+
/**
* munlock_vma_page - munlock a vma page
* @page - page to be unlocked
unsigned int nr_pages = hpage_nr_pages(page);
mod_zone_page_state(page_zone(page), NR_MLOCK, -nr_pages);
page_mask = nr_pages - 1;
- if (!isolate_lru_page(page)) {
- int ret = SWAP_AGAIN;
-
- /*
- * Optimization: if the page was mapped just once,
- * that's our mapping and we don't need to check all the
- * other vmas.
- */
- if (page_mapcount(page) > 1)
- ret = try_to_munlock(page);
- /*
- * did try_to_unlock() succeed or punt?
- */
- if (ret != SWAP_MLOCK)
- count_vm_event(UNEVICTABLE_PGMUNLOCKED);
-
- putback_lru_page(page);
- } else {
- /*
- * Some other task has removed the page from the LRU.
- * putback_lru_page() will take care of removing the
- * page from the unevictable list, if necessary.
- * vmscan [page_referenced()] will move the page back
- * to the unevictable list if some other vma has it
- * mlocked.
- */
- if (PageUnevictable(page))
- count_vm_event(UNEVICTABLE_PGSTRANDED);
- else
- count_vm_event(UNEVICTABLE_PGMUNLOCKED);
- }
+ if (!isolate_lru_page(page))
+ __munlock_isolated_page(page);
+ else
+ __munlock_isolation_failed(page);
}
return page_mask;
return retval;
}
+/*
+ * Prepare page for fast batched LRU putback via putback_lru_evictable_pagevec()
+ *
+ * The fast path is available only for evictable pages with single mapping.
+ * Then we can bypass the per-cpu pvec and get better performance.
+ * when mapcount > 1 we need try_to_munlock() which can fail.
+ * when !page_evictable(), we need the full redo logic of putback_lru_page to
+ * avoid leaving evictable page in unevictable list.
+ *
+ * In case of success, @page is added to @pvec and @pgrescued is incremented
+ * in case that the page was previously unevictable. @page is also unlocked.
+ */
+static bool __putback_lru_fast_prepare(struct page *page, struct pagevec *pvec,
+ int *pgrescued)
+{
+ VM_BUG_ON(PageLRU(page));
+ VM_BUG_ON(!PageLocked(page));
+
+ if (page_mapcount(page) <= 1 && page_evictable(page)) {
+ pagevec_add(pvec, page);
+ if (TestClearPageUnevictable(page))
+ (*pgrescued)++;
+ unlock_page(page);
+ return true;
+ }
+
+ return false;
+}
+
+/*
+ * Putback multiple evictable pages to the LRU
+ *
+ * Batched putback of evictable pages that bypasses the per-cpu pvec. Some of
+ * the pages might have meanwhile become unevictable but that is OK.
+ */
+static void __putback_lru_fast(struct pagevec *pvec, int pgrescued)
+{
+ count_vm_events(UNEVICTABLE_PGMUNLOCKED, pagevec_count(pvec));
+ /*
+ *__pagevec_lru_add() calls release_pages() so we don't call
+ * put_page() explicitly
+ */
+ __pagevec_lru_add(pvec);
+ count_vm_events(UNEVICTABLE_PGRESCUED, pgrescued);
+}
+
+/*
+ * Munlock a batch of pages from the same zone
+ *
+ * The work is split to two main phases. First phase clears the Mlocked flag
+ * and attempts to isolate the pages, all under a single zone lru lock.
+ * The second phase finishes the munlock only for pages where isolation
+ * succeeded.
+ *
+ * Note that pvec is modified during the process. Before returning
+ * pagevec_reinit() is called on it.
+ */
+static void __munlock_pagevec(struct pagevec *pvec, struct zone *zone)
+{
+ int i;
+ int nr = pagevec_count(pvec);
+ int delta_munlocked = -nr;
+ struct pagevec pvec_putback;
+ int pgrescued = 0;
+
+ /* Phase 1: page isolation */
+ spin_lock_irq(&zone->lru_lock);
+ for (i = 0; i < nr; i++) {
+ struct page *page = pvec->pages[i];
+
+ if (TestClearPageMlocked(page)) {
+ struct lruvec *lruvec;
+ int lru;
+
+ if (PageLRU(page)) {
+ lruvec = mem_cgroup_page_lruvec(page, zone);
+ lru = page_lru(page);
+ /*
+ * We already have pin from follow_page_mask()
+ * so we can spare the get_page() here.
+ */
+ ClearPageLRU(page);
+ del_page_from_lru_list(page, lruvec, lru);
+ } else {
+ __munlock_isolation_failed(page);
+ goto skip_munlock;
+ }
+
+ } else {
+skip_munlock:
+ /*
+ * We won't be munlocking this page in the next phase
+ * but we still need to release the follow_page_mask()
+ * pin.
+ */
+ pvec->pages[i] = NULL;
+ put_page(page);
+ delta_munlocked++;
+ }
+ }
+ __mod_zone_page_state(zone, NR_MLOCK, delta_munlocked);
+ spin_unlock_irq(&zone->lru_lock);
+
+ /* Phase 2: page munlock */
+ pagevec_init(&pvec_putback, 0);
+ for (i = 0; i < nr; i++) {
+ struct page *page = pvec->pages[i];
+
+ if (page) {
+ lock_page(page);
+ if (!__putback_lru_fast_prepare(page, &pvec_putback,
+ &pgrescued)) {
+ /*
+ * Slow path. We don't want to lose the last
+ * pin before unlock_page()
+ */
+ get_page(page); /* for putback_lru_page() */
+ __munlock_isolated_page(page);
+ unlock_page(page);
+ put_page(page); /* from follow_page_mask() */
+ }
+ }
+ }
+
+ /*
+ * Phase 3: page putback for pages that qualified for the fast path
+ * This will also call put_page() to return pin from follow_page_mask()
+ */
+ if (pagevec_count(&pvec_putback))
+ __putback_lru_fast(&pvec_putback, pgrescued);
+
+ pagevec_reinit(pvec);
+}
+
/*
* munlock_vma_pages_range() - munlock all pages in the vma range.'
* @vma - vma containing range to be munlock()ed.
void munlock_vma_pages_range(struct vm_area_struct *vma,
unsigned long start, unsigned long end)
{
+ struct pagevec pvec;
+ struct zone *zone = NULL;
+
+ pagevec_init(&pvec, 0);
vma->vm_flags &= ~VM_LOCKED;
while (start < end) {
struct page *page;
unsigned int page_mask, page_increm;
+ struct zone *pagezone;
/*
* Although FOLL_DUMP is intended for get_dump_page(),
page = follow_page_mask(vma, start, FOLL_GET | FOLL_DUMP,
&page_mask);
if (page && !IS_ERR(page)) {
- lock_page(page);
- lru_add_drain();
- /*
- * Any THP page found by follow_page_mask() may have
- * gotten split before reaching munlock_vma_page(),
- * so we need to recompute the page_mask here.
- */
- page_mask = munlock_vma_page(page);
- unlock_page(page);
- put_page(page);
+ pagezone = page_zone(page);
+ /* The whole pagevec must be in the same zone */
+ if (pagezone != zone) {
+ if (pagevec_count(&pvec))
+ __munlock_pagevec(&pvec, zone);
+ zone = pagezone;
+ }
+ if (PageTransHuge(page)) {
+ /*
+ * THP pages are not handled by pagevec due
+ * to their possible split (see below).
+ */
+ if (pagevec_count(&pvec))
+ __munlock_pagevec(&pvec, zone);
+ lock_page(page);
+ /*
+ * Any THP page found by follow_page_mask() may
+ * have gotten split before reaching
+ * munlock_vma_page(), so we need to recompute
+ * the page_mask here.
+ */
+ page_mask = munlock_vma_page(page);
+ unlock_page(page);
+ put_page(page); /* follow_page_mask() */
+ } else {
+ /*
+ * Non-huge pages are handled in batches
+ * via pagevec. The pin from
+ * follow_page_mask() prevents them from
+ * collapsing by THP.
+ */
+ if (pagevec_add(&pvec, page) == 0)
+ __munlock_pagevec(&pvec, zone);
+ }
}
page_increm = 1 + (~(start >> PAGE_SHIFT) & page_mask);
start += page_increm * PAGE_SIZE;
cond_resched();
}
+ if (pagevec_count(&pvec))
+ __munlock_pagevec(&pvec, zone);
}
/*
projects / ~andy / linux / blobdiff