4.9-stable review patch. If anyone has any objections, please let me know.
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commit 042a30824871fa3149b0127009074b75cc25863c upstream.
Several cleanups in collapse_shmem(): most of which probably do not really matter, beyond doing things in a more familiar and reassuring order. Simplify the failure gotos in the main loop, and on success update stats while interrupts still disabled from the last iteration.
Link: http://lkml.kernel.org/r/alpine.LSU.2.11.1811261526400.2275@eggly.anvils Fixes: f3f0e1d2150b2 ("khugepaged: add support of collapse for tmpfs/shmem pages") Signed-off-by: Hugh Dickins hughd@google.com Acked-by: Kirill A. Shutemov kirill.shutemov@linux.intel.com Cc: Jerome Glisse jglisse@redhat.com Cc: Konstantin Khlebnikov khlebnikov@yandex-team.ru Cc: Matthew Wilcox willy@infradead.org Cc: stable@vger.kernel.org [4.8+] Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Sasha Levin sashal@kernel.org --- mm/khugepaged.c | 73 ++++++++++++++++++++----------------------------- 1 file changed, 30 insertions(+), 43 deletions(-)
diff --git a/mm/khugepaged.c b/mm/khugepaged.c index 2d3ce49f6b45..47b83030fc53 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -1332,13 +1332,12 @@ static void collapse_shmem(struct mm_struct *mm, goto out; }
+ __SetPageLocked(new_page); + __SetPageSwapBacked(new_page); new_page->index = start; new_page->mapping = mapping; - __SetPageSwapBacked(new_page); - __SetPageLocked(new_page); BUG_ON(!page_ref_freeze(new_page, 1));
- /* * At this point the new_page is 'frozen' (page_count() is zero), locked * and not up-to-date. It's safe to insert it into radix tree, because @@ -1367,13 +1366,13 @@ static void collapse_shmem(struct mm_struct *mm, */ if (n && !shmem_charge(mapping->host, n)) { result = SCAN_FAIL; - break; + goto tree_locked; } - nr_none += n; for (; index < min(iter.index, end); index++) { radix_tree_insert(&mapping->page_tree, index, new_page + (index % HPAGE_PMD_NR)); } + nr_none += n;
/* We are done. */ if (index >= end) @@ -1389,12 +1388,12 @@ static void collapse_shmem(struct mm_struct *mm, result = SCAN_FAIL; goto tree_unlocked; } - spin_lock_irq(&mapping->tree_lock); } else if (trylock_page(page)) { get_page(page); + spin_unlock_irq(&mapping->tree_lock); } else { result = SCAN_PAGE_LOCK; - break; + goto tree_locked; }
/* @@ -1409,11 +1408,10 @@ static void collapse_shmem(struct mm_struct *mm, result = SCAN_TRUNCATED; goto out_unlock; } - spin_unlock_irq(&mapping->tree_lock);
if (isolate_lru_page(page)) { result = SCAN_DEL_PAGE_LRU; - goto out_isolate_failed; + goto out_unlock; }
if (page_mapped(page)) @@ -1435,7 +1433,9 @@ static void collapse_shmem(struct mm_struct *mm, */ if (!page_ref_freeze(page, 3)) { result = SCAN_PAGE_COUNT; - goto out_lru; + spin_unlock_irq(&mapping->tree_lock); + putback_lru_page(page); + goto out_unlock; }
/* @@ -1451,17 +1451,10 @@ static void collapse_shmem(struct mm_struct *mm, slot = radix_tree_iter_next(&iter); index++; continue; -out_lru: - spin_unlock_irq(&mapping->tree_lock); - putback_lru_page(page); -out_isolate_failed: - unlock_page(page); - put_page(page); - goto tree_unlocked; out_unlock: unlock_page(page); put_page(page); - break; + goto tree_unlocked; }
/* @@ -1469,7 +1462,7 @@ static void collapse_shmem(struct mm_struct *mm, * This code only triggers if there's nothing in radix tree * beyond 'end'. */ - if (result == SCAN_SUCCEED && index < end) { + if (index < end) { int n = end - index;
/* Stop if extent has been truncated, and is now empty */ @@ -1481,7 +1474,6 @@ static void collapse_shmem(struct mm_struct *mm, result = SCAN_FAIL; goto tree_locked; } - for (; index < end; index++) { radix_tree_insert(&mapping->page_tree, index, new_page + (index % HPAGE_PMD_NR)); @@ -1489,14 +1481,19 @@ static void collapse_shmem(struct mm_struct *mm, nr_none += n; }
+ __inc_node_page_state(new_page, NR_SHMEM_THPS); + if (nr_none) { + struct zone *zone = page_zone(new_page); + + __mod_node_page_state(zone->zone_pgdat, NR_FILE_PAGES, nr_none); + __mod_node_page_state(zone->zone_pgdat, NR_SHMEM, nr_none); + } + tree_locked: spin_unlock_irq(&mapping->tree_lock); tree_unlocked:
if (result == SCAN_SUCCEED) { - unsigned long flags; - struct zone *zone = page_zone(new_page); - /* * Replacing old pages with new one has succeed, now we need to * copy the content and free old pages. @@ -1510,11 +1507,11 @@ static void collapse_shmem(struct mm_struct *mm, copy_highpage(new_page + (page->index % HPAGE_PMD_NR), page); list_del(&page->lru); - unlock_page(page); - page_ref_unfreeze(page, 1); page->mapping = NULL; + page_ref_unfreeze(page, 1); ClearPageActive(page); ClearPageUnevictable(page); + unlock_page(page); put_page(page); index++; } @@ -1523,28 +1520,17 @@ static void collapse_shmem(struct mm_struct *mm, index++; }
- local_irq_save(flags); - __inc_node_page_state(new_page, NR_SHMEM_THPS); - if (nr_none) { - __mod_node_page_state(zone->zone_pgdat, NR_FILE_PAGES, nr_none); - __mod_node_page_state(zone->zone_pgdat, NR_SHMEM, nr_none); - } - local_irq_restore(flags); - - /* - * Remove pte page tables, so we can re-faulti - * the page as huge. - */ - retract_page_tables(mapping, start); - /* Everything is ready, let's unfreeze the new_page */ - set_page_dirty(new_page); SetPageUptodate(new_page); page_ref_unfreeze(new_page, HPAGE_PMD_NR); + set_page_dirty(new_page); mem_cgroup_commit_charge(new_page, memcg, false, true); lru_cache_add_anon(new_page); - unlock_page(new_page);
+ /* + * Remove pte page tables, so we can re-fault the page as huge. + */ + retract_page_tables(mapping, start); *hpage = NULL; } else { /* Something went wrong: rollback changes to the radix-tree */ @@ -1576,8 +1562,8 @@ static void collapse_shmem(struct mm_struct *mm, page_ref_unfreeze(page, 2); radix_tree_replace_slot(slot, page); spin_unlock_irq(&mapping->tree_lock); - putback_lru_page(page); unlock_page(page); + putback_lru_page(page); spin_lock_irq(&mapping->tree_lock); slot = radix_tree_iter_next(&iter); } @@ -1587,9 +1573,10 @@ static void collapse_shmem(struct mm_struct *mm, /* Unfreeze new_page, caller would take care about freeing it */ page_ref_unfreeze(new_page, 1); mem_cgroup_cancel_charge(new_page, memcg, true); - unlock_page(new_page); new_page->mapping = NULL; } + + unlock_page(new_page); out: VM_BUG_ON(!list_empty(&pagelist)); /* TODO: tracepoints */