lru_lock and page cache xa_lock have no reason with current sequence,
put them together isn't necessary. let's narrow the lru locking, but
left the local_irq_disable to block interrupt re-entry and statistic update.
Hugh Dickins point: split_huge_page_to_list() was already silly,to be
using the _irqsave variant: it's just been taking sleeping locks, so
would already be broken if entered with interrupts enabled.
so we can save passing flags argument down to __split_huge_page().
Signed-off-by: Alex Shi <alex....@linux.alibaba.com>
Signed-off-by: Wei Yang <richard.weiy...@gmail.com>
Cc: Hugh Dickins <hu...@google.com>
Cc: Kirill A. Shutemov <kir...@shutemov.name>
Cc: Andrea Arcangeli <aarca...@redhat.com>
Cc: Johannes Weiner <han...@cmpxchg.org>
Cc: Matthew Wilcox <wi...@infradead.org>
Cc: Andrew Morton <a...@linux-foundation.org>
Cc: linux...@kvack.org
Cc: linux-kernel@vger.kernel.org
---
mm/huge_memory.c | 24 ++++++++++++------------
1 file changed, 12 insertions(+), 12 deletions(-)
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index b18f21da4dac..607869330329 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -2433,7 +2433,7 @@ static void __split_huge_page_tail(struct page *head, int
tail,
}
static void __split_huge_page(struct page *page, struct list_head *list,
- pgoff_t end, unsigned long flags)
+ pgoff_t end)
{
struct page *head = compound_head(page);
pg_data_t *pgdat = page_pgdat(head);
@@ -2442,8 +2442,6 @@ static void __split_huge_page(struct page *page, struct
list_head *list,
unsigned long offset = 0;
int i;
- lruvec = mem_cgroup_page_lruvec(head, pgdat);
-
/* complete memcg works before add pages to LRU */
mem_cgroup_split_huge_fixup(head);
@@ -2455,6 +2453,11 @@ static void __split_huge_page(struct page *page, struct
list_head *list,
xa_lock(&swap_cache->i_pages);
}
+ /* lock lru list/PageCompound, ref freezed by page_ref_freeze */
+ spin_lock(&pgdat->lru_lock);
+
+ lruvec = mem_cgroup_page_lruvec(head, pgdat);
+
for (i = HPAGE_PMD_NR - 1; i >= 1; i--) {
__split_huge_page_tail(head, i, lruvec, list);
/* Some pages can be beyond i_size: drop them from page cache */
@@ -2474,6 +2477,8 @@ static void __split_huge_page(struct page *page, struct
list_head *list,
}
ClearPageCompound(head);
+ spin_unlock(&pgdat->lru_lock);
+ /* Caller disabled irqs, so they are still disabled here */
split_page_owner(head, HPAGE_PMD_ORDER);
@@ -2491,8 +2496,7 @@ static void __split_huge_page(struct page *page, struct
list_head *list,
page_ref_add(head, 2);
xa_unlock(&head->mapping->i_pages);
}
-
- spin_unlock_irqrestore(&pgdat->lru_lock, flags);
+ local_irq_enable();
remap_page(head);
@@ -2631,12 +2635,10 @@ bool can_split_huge_page(struct page *page, int
*pextra_pins)
int split_huge_page_to_list(struct page *page, struct list_head *list)
{
struct page *head = compound_head(page);
- struct pglist_data *pgdata = NODE_DATA(page_to_nid(head));
struct deferred_split *ds_queue = get_deferred_split_queue(head);
struct anon_vma *anon_vma = NULL;
struct address_space *mapping = NULL;
int count, mapcount, extra_pins, ret;
- unsigned long flags;
pgoff_t end;
VM_BUG_ON_PAGE(is_huge_zero_page(head), head);
@@ -2697,9 +2699,7 @@ int split_huge_page_to_list(struct page *page, struct
list_head *list)
unmap_page(head);
VM_BUG_ON_PAGE(compound_mapcount(head), head);
- /* prevent PageLRU to go away from under us, and freeze lru stats */
- spin_lock_irqsave(&pgdata->lru_lock, flags);
-
+ local_irq_disable();
if (mapping) {
XA_STATE(xas, &mapping->i_pages, page_index(head));
@@ -2729,7 +2729,7 @@ int split_huge_page_to_list(struct page *page, struct
list_head *list)
__dec_node_page_state(head, NR_FILE_THPS);
}
- __split_huge_page(page, list, end, flags);
+ __split_huge_page(page, list, end);
if (PageSwapCache(head)) {
swp_entry_t entry = { .val = page_private(head) };
@@ -2748,7 +2748,7 @@ int split_huge_page_to_list(struct page *page, struct
list_head *list)
spin_unlock(&ds_queue->split_queue_lock);
fail: if (mapping)
xa_unlock(&mapping->i_pages);
- spin_unlock_irqrestore(&pgdata->lru_lock, flags);
+ local_irq_enable();
remap_page(head);
ret = -EBUSY;
}
--
1.8.3.1
