From: Andrew Morton <akpm@linux-foundation.org>
To: aarcange@redhat.com, akpm@linux-foundation.org,
alex.shi@linux.alibaba.com, alexander.duyck@gmail.com,
aryabinin@virtuozzo.com, daniel.m.jordan@oracle.com,
hannes@cmpxchg.org, hughd@google.com, iamjoonsoo.kim@lge.com,
jannh@google.com, khlebnikov@yandex-team.ru,
kirill.shutemov@linux.intel.com, kirill@shutemov.name,
linux-mm@kvack.org, mgorman@techsingularity.net,
mhocko@kernel.org, mhocko@suse.com, mika.penttila@nextfour.com,
minchan@kernel.org, mm-commits@vger.kernel.org,
richard.weiyang@gmail.com, rong.a.chen@intel.com,
shakeelb@google.com, tglx@linutronix.de, tj@kernel.org,
torvalds@linux-foundation.org, vbabka@suse.cz,
vdavydov.dev@gmail.com, willy@infradead.org,
yang.shi@linux.alibaba.com, ying.huang@intel.com
Subject: [patch 04/19] mm/thp: narrow lru locking
Date: Tue, 15 Dec 2020 14:20:24 -0800 [thread overview]
Message-ID: <20201215222024.XDeNGvndP%akpm@linux-foundation.org> (raw)
In-Reply-To: <20201215123253.954eca9a5ef4c0d52fd381fa@linux-foundation.org>
From: Alex Shi <alex.shi@linux.alibaba.com>
Subject: mm/thp: narrow lru locking
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.
[hughd@google.com: rewrite commit log]
Link: https://lkml.kernel.org/r/1604566549-62481-5-git-send-email-alex.shi@linux.alibaba.com
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: 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: Alexander Duyck <alexander.duyck@gmail.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: "Chen, Rong A" <rong.a.chen@intel.com>
Cc: Daniel Jordan <daniel.m.jordan@oracle.com>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Jann Horn <jannh@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mika Penttilä <mika.penttila@nextfour.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: Yang Shi <yang.shi@linux.alibaba.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
mm/huge_memory.c | 25 +++++++++++++------------
1 file changed, 13 insertions(+), 12 deletions(-)
--- a/mm/huge_memory.c~mm-thp-narrow-lru-locking
+++ a/mm/huge_memory.c
@@ -2446,7 +2446,7 @@ static void __split_huge_page_tail(struc
}
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);
@@ -2456,8 +2456,6 @@ static void __split_huge_page(struct pag
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);
@@ -2469,6 +2467,11 @@ static void __split_huge_page(struct pag
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 */
@@ -2488,6 +2491,8 @@ static void __split_huge_page(struct pag
}
ClearPageCompound(head);
+ spin_unlock(&pgdat->lru_lock);
+ /* Caller disabled irqs, so they are still disabled here */
split_page_owner(head, nr);
@@ -2505,8 +2510,7 @@ static void __split_huge_page(struct pag
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);
@@ -2652,12 +2656,10 @@ bool can_split_huge_page(struct page *pa
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);
@@ -2718,9 +2720,8 @@ int split_huge_page_to_list(struct page
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));
@@ -2750,7 +2751,7 @@ int split_huge_page_to_list(struct page
__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) {
@@ -2764,7 +2765,7 @@ int split_huge_page_to_list(struct page
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;
}
_
next prev parent reply other threads:[~2020-12-15 22:20 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-15 20:32 incoming Andrew Morton
2020-12-15 20:33 ` [patch 01/19] mm/thp: move lru_add_page_tail() to huge_memory.c Andrew Morton
2020-12-15 20:33 ` [patch 02/19] mm/thp: use head for head page in lru_add_page_tail() Andrew Morton
2020-12-15 20:33 ` [patch 03/19] mm/thp: simplify lru_add_page_tail() Andrew Morton
2020-12-15 20:33 ` [patch 04/19] mm/thp: narrow lru locking Andrew Morton
2020-12-15 20:33 ` [patch 05/19] mm/vmscan: remove unnecessary lruvec adding Andrew Morton
2020-12-15 20:33 ` [patch 06/19] mm/rmap: stop store reordering issue on page->mapping Andrew Morton
2020-12-15 20:33 ` [patch 07/19] mm: page_idle_get_page() does not need lru_lock Andrew Morton
2020-12-15 20:33 ` [patch 08/19] mm/memcg: add debug checking in lock_page_memcg Andrew Morton
2020-12-15 20:33 ` [patch 09/19] mm/swap.c: fold vm event PGROTATED into pagevec_move_tail_fn Andrew Morton
2020-12-15 20:34 ` [patch 11/19] mm/vmscan: remove lruvec reget in move_pages_to_lru Andrew Morton
2020-12-15 20:34 ` [patch 12/19] mm/mlock: remove lru_lock on TestClearPageMlocked Andrew Morton
2020-12-15 20:34 ` [patch 13/19] mm/mlock: remove __munlock_isolate_lru_page() Andrew Morton
2020-12-15 20:34 ` [patch 14/19] mm/lru: introduce TestClearPageLRU() Andrew Morton
2020-12-15 20:34 ` [patch 15/19] mm/compaction: do page isolation first in compaction Andrew Morton
2020-12-15 20:34 ` [patch 16/19] mm/swap.c: serialize memcg changes in pagevec_lru_move_fn Andrew Morton
2020-12-15 20:34 ` [patch 17/19] mm/lru: replace pgdat lru_lock with lruvec lock Andrew Morton
2020-12-15 20:34 ` [patch 18/19] mm/lru: introduce relock_page_lruvec() Andrew Morton
2020-12-15 20:34 ` [patch 19/19] mm/lru: revise the comments of lru_lock Andrew Morton
2020-12-15 21:00 ` incoming Linus Torvalds
2020-12-15 22:20 ` [patch 01/19] mm/thp: move lru_add_page_tail() to huge_memory.c Andrew Morton
2020-12-15 22:20 ` [patch 02/19] mm/thp: use head for head page in lru_add_page_tail() Andrew Morton
2020-12-15 22:20 ` [patch 03/19] mm/thp: simplify lru_add_page_tail() Andrew Morton
2020-12-15 22:20 ` Andrew Morton [this message]
2020-12-15 22:20 ` [patch 05/19] mm/vmscan: remove unnecessary lruvec adding Andrew Morton
2020-12-15 22:20 ` [patch 06/19] mm/rmap: stop store reordering issue on page->mapping Andrew Morton
2020-12-15 22:20 ` [patch 07/19] mm: page_idle_get_page() does not need lru_lock Andrew Morton
2020-12-15 22:20 ` [patch 08/19] mm/memcg: add debug checking in lock_page_memcg Andrew Morton
2020-12-15 22:20 ` [patch 09/19] mm/swap.c: fold vm event PGROTATED into pagevec_move_tail_fn Andrew Morton
2020-12-15 22:20 ` [patch 10/19] mm/lru: move lock into lru_note_cost Andrew Morton
2020-12-15 22:20 ` [patch 11/19] mm/vmscan: remove lruvec reget in move_pages_to_lru Andrew Morton
2020-12-15 22:20 ` [patch 12/19] mm/mlock: remove lru_lock on TestClearPageMlocked Andrew Morton
2020-12-15 22:21 ` [patch 13/19] mm/mlock: remove __munlock_isolate_lru_page() Andrew Morton
2020-12-15 22:21 ` [patch 14/19] mm/lru: introduce TestClearPageLRU() Andrew Morton
2020-12-15 22:21 ` [patch 15/19] mm/compaction: do page isolation first in compaction Andrew Morton
2020-12-15 22:21 ` [patch 16/19] mm/swap.c: serialize memcg changes in pagevec_lru_move_fn Andrew Morton
2020-12-15 22:21 ` [patch 17/19] mm/lru: replace pgdat lru_lock with lruvec lock Andrew Morton
2020-12-15 22:21 ` [patch 18/19] mm/lru: introduce relock_page_lruvec() Andrew Morton
2020-12-15 22:21 ` [patch 19/19] mm/lru: revise the comments of lru_lock Andrew Morton
2020-12-15 22:48 ` incoming Linus Torvalds
2020-12-15 22:49 ` incoming Linus Torvalds
2020-12-15 22:55 ` incoming Andrew Morton
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