From: Alex Shi <alex.shi@linux.alibaba.com>
To: akpm@linux-foundation.org, mgorman@techsingularity.net,
tj@kernel.org, hughd@google.com, khlebnikov@yandex-team.ru,
daniel.m.jordan@oracle.com, willy@infradead.org,
hannes@cmpxchg.org, lkp@intel.com, linux-mm@kvack.org,
linux-kernel@vger.kernel.org, cgroups@vger.kernel.org,
shakeelb@google.com, iamjoonsoo.kim@lge.com,
richard.weiyang@gmail.com, kirill@shutemov.name,
alexander.duyck@gmail.com, rong.a.chen@intel.com,
mhocko@suse.com, vdavydov.dev@gmail.com, shy828301@gmail.com
Cc: Andrea Arcangeli <aarcange@redhat.com>
Subject: [PATCH v21 04/19] mm/thp: narrow lru locking
Date: Thu, 5 Nov 2020 16:55:34 +0800 [thread overview]
Message-ID: <1604566549-62481-5-git-send-email-alex.shi@linux.alibaba.com> (raw)
In-Reply-To: <1604566549-62481-1-git-send-email-alex.shi@linux.alibaba.com>
lru_lock and page cache xa_lock have no obvious reason to be taken
one way round or the other: until now, lru_lock has been taken before
page cache xa_lock, when splitting a THP; but nothing else takes them
together. Reverse that ordering: let's narrow the lru locking - but
leave local_irq_disable to block interrupts throughout, like before.
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().
Why change the lock ordering here? That was hard to decide. One reason:
when this series reaches per-memcg lru locking, it relies on the THP's
memcg to be stable when taking the lru_lock: that is now done after the
THP's refcount has been frozen, which ensures page memcg cannot change.
Another reason: previously, lock_page_memcg()'s move_lock was presumed
to nest inside lru_lock; but now lru_lock must nest inside (page cache
lock inside) move_lock, so it becomes possible to use lock_page_memcg()
to stabilize page memcg before taking its lru_lock. That is not the
mechanism used in this series, but it is an option we want to keep open.
[Hugh Dickins: rewrite commit log]
Signed-off-by: Alex Shi <alex.shi@linux.alibaba.com>
Reviewed-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Hugh Dickins <hughd@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Kirill A. Shutemov <kirill@shutemov.name>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-mm@kvack.org
Cc: linux-kernel@vger.kernel.org
---
mm/huge_memory.c | 25 +++++++++++++------------
1 file changed, 13 insertions(+), 12 deletions(-)
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 79318d7f7d5d..b70ec0c6076b 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -2435,7 +2435,7 @@ 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);
@@ -2445,8 +2445,6 @@ static void __split_huge_page(struct page *page, struct list_head *list,
unsigned int nr = thp_nr_pages(head);
int i;
- lruvec = mem_cgroup_page_lruvec(head, pgdat);
-
/* complete memcg works before add pages to LRU */
mem_cgroup_split_huge_fixup(head);
@@ -2458,6 +2456,11 @@ static void __split_huge_page(struct page *page, struct list_head *list,
xa_lock(&swap_cache->i_pages);
}
+ /* prevent PageLRU to go away from under us, and freeze lru stats */
+ spin_lock(&pgdat->lru_lock);
+
+ lruvec = mem_cgroup_page_lruvec(head, pgdat);
+
for (i = 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 */
@@ -2477,6 +2480,8 @@ 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, nr);
@@ -2494,8 +2499,7 @@ 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, nr);
@@ -2641,12 +2645,10 @@ 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);
@@ -2707,9 +2709,8 @@ 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);
-
+ /* block interrupt reentry in xa_lock and spinlock */
+ local_irq_disable();
if (mapping) {
XA_STATE(xas, &mapping->i_pages, page_index(head));
@@ -2739,7 +2740,7 @@ int split_huge_page_to_list(struct page *page, struct list_head *list)
__dec_lruvec_page_state(head, NR_FILE_THPS);
}
- __split_huge_page(page, list, end, flags);
+ __split_huge_page(page, list, end);
ret = 0;
} else {
if (IS_ENABLED(CONFIG_DEBUG_VM) && mapcount) {
@@ -2753,7 +2754,7 @@ 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, thp_nr_pages(head));
ret = -EBUSY;
}
--
1.8.3.1
next prev parent reply other threads:[~2020-11-05 8:57 UTC|newest]
Thread overview: 59+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-05 8:55 [PATCH v21 00/19] per memcg lru lock Alex Shi
2020-11-05 8:55 ` [PATCH v21 01/19] mm/thp: move lru_add_page_tail func to huge_memory.c Alex Shi
2020-11-05 8:55 ` [PATCH v21 02/19] mm/thp: use head for head page in lru_add_page_tail Alex Shi
2020-11-05 8:55 ` [PATCH v21 03/19] mm/thp: Simplify lru_add_page_tail() Alex Shi
2020-11-05 8:55 ` Alex Shi [this message]
2020-11-05 8:55 ` [PATCH v21 05/19] mm/vmscan: remove unnecessary lruvec adding Alex Shi
2020-11-11 12:36 ` Vlastimil Babka
2020-11-05 8:55 ` [PATCH v21 06/19] mm/rmap: stop store reordering issue on page->mapping Alex Shi
2020-11-06 1:20 ` Alex Shi
2020-11-10 19:06 ` Johannes Weiner
2020-11-11 7:41 ` Hugh Dickins
2020-11-05 8:55 ` [PATCH v21 07/19] mm: page_idle_get_page() does not need lru_lock Alex Shi
2020-11-10 19:01 ` Johannes Weiner
2020-11-11 8:17 ` huang ying
2020-11-11 12:52 ` Vlastimil Babka
2020-11-05 8:55 ` [PATCH v21 08/19] mm/memcg: add debug checking in lock_page_memcg Alex Shi
2020-11-05 8:55 ` [PATCH v21 09/19] mm/swap.c: fold vm event PGROTATED into pagevec_move_tail_fn Alex Shi
2020-11-05 8:55 ` [PATCH v21 10/19] mm/lru: move lock into lru_note_cost Alex Shi
2020-11-05 8:55 ` [PATCH v21 11/19] mm/vmscan: remove lruvec reget in move_pages_to_lru Alex Shi
2020-11-05 8:55 ` [PATCH v21 12/19] mm/mlock: remove lru_lock on TestClearPageMlocked Alex Shi
2020-11-11 13:03 ` Vlastimil Babka
2020-11-05 8:55 ` [PATCH v21 13/19] mm/mlock: remove __munlock_isolate_lru_page Alex Shi
2020-11-11 13:07 ` Vlastimil Babka
2020-11-05 8:55 ` [PATCH v21 14/19] mm/lru: introduce TestClearPageLRU Alex Shi
2020-11-11 13:36 ` Vlastimil Babka
2020-11-12 2:03 ` Hugh Dickins
2020-11-12 11:24 ` Vlastimil Babka
2020-11-05 8:55 ` [PATCH v21 15/19] mm/compaction: do page isolation first in compaction Alex Shi
2020-11-11 17:12 ` Vlastimil Babka
2020-11-12 2:28 ` Hugh Dickins
2020-11-12 3:35 ` Alex Shi
2020-11-12 11:25 ` Vlastimil Babka
2020-11-05 8:55 ` [PATCH v21 16/19] mm/swap.c: serialize memcg changes in pagevec_lru_move_fn Alex Shi
2020-11-11 18:00 ` Vlastimil Babka
2020-11-05 8:55 ` [PATCH v21 17/19] mm/lru: replace pgdat lru_lock with lruvec lock Alex Shi
2020-11-05 13:43 ` Alex Shi
2020-11-06 7:48 ` Alex Shi
2020-11-10 18:54 ` Johannes Weiner
2020-11-11 17:46 ` Vlastimil Babka
2020-11-11 17:59 ` Vlastimil Babka
2020-11-12 12:19 ` Vlastimil Babka
2020-11-12 14:19 ` Alex Shi
2020-11-05 8:55 ` [PATCH v21 18/19] mm/lru: introduce the relock_page_lruvec function Alex Shi
2020-11-06 7:50 ` Alex Shi
2020-11-10 18:59 ` Johannes Weiner
2020-11-12 12:31 ` Vlastimil Babka
2020-11-05 8:55 ` [PATCH v21 19/19] mm/lru: revise the comments of lru_lock Alex Shi
2020-11-12 12:37 ` Vlastimil Babka
2020-11-10 12:14 ` [PATCH v21 00/19] per memcg lru lock Alex Shi
2020-11-16 3:45 ` Alex Shi
2020-12-15 0:47 ` Andrew Morton
2020-12-15 2:16 ` Hugh Dickins
2020-12-15 2:28 ` Andrew Morton
2021-01-05 19:30 ` Qian Cai
2021-01-05 19:42 ` Shakeel Butt
2021-01-05 20:11 ` Qian Cai
2021-01-05 21:35 ` Hugh Dickins
2021-01-05 22:01 ` Qian Cai
2021-01-06 3:10 ` Hugh Dickins
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