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mm/khugepaged: minor reorderings in collapse_shmem()

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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>
This commit is contained in:
Hugh Dickins 2018-11-30 14:10:39 -08:00 committed by Greg Kroah-Hartman
parent 5021918a51
commit b447a6adf4
1 changed files with 30 additions and 43 deletions
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73
mm/khugepaged.c
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@ -1333,13 +1333,12 @@ 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
@ -1368,13 +1367,13 @@ 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)
@ -1390,12 +1389,12 @@ 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;
}
/*
@ -1410,11 +1409,10 @@ 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))
@ -1436,7 +1434,9 @@ 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;
}
/*
@ -1452,17 +1452,10 @@ static void collapse_shmem(struct mm_struct *mm,
slot = radix_tree_iter_resume(slot, &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;
}
/*
@ -1470,7 +1463,7 @@ out_unlock:
* 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 */
@ -1482,7 +1475,6 @@ out_unlock:
result = SCAN_FAIL;
goto tree_locked;
}
for (; index < end; index++) {
radix_tree_insert(&mapping->page_tree, index,
new_page + (index % HPAGE_PMD_NR));
@ -1490,14 +1482,19 @@ out_unlock:
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.
@ -1511,11 +1508,11 @@ tree_unlocked:
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++;
}
@ -1524,28 +1521,17 @@ tree_unlocked:
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 */
@ -1578,8 +1564,8 @@ tree_unlocked:
slot, page);
slot = radix_tree_iter_resume(slot, &iter);
spin_unlock_irq(&mapping->tree_lock);
putback_lru_page(page);
unlock_page(page);
putback_lru_page(page);
spin_lock_irq(&mapping->tree_lock);
}
VM_BUG_ON(nr_none);
@ -1588,9 +1574,10 @@ tree_unlocked:
/* 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 */