From: Alex Shi <alex.shi@linux.alibaba.com>
To: Matthew Wilcox <willy@infradead.org>
Cc: akpm@linux-foundation.org, mgorman@techsingularity.net,
tj@kernel.org, hughd@google.com, khlebnikov@yandex-team.ru,
daniel.m.jordan@oracle.com, 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, Andrea Arcangeli <aarcange@redhat.com>
Subject: Re: [PATCH v18 06/32] mm/thp: narrow lru locking
Date: Fri, 11 Sep 2020 11:37:50 +0800 [thread overview]
Message-ID: <514f6afa-dbf7-11c5-5431-1d558d2c20c9@linux.alibaba.com> (raw)
In-Reply-To: <20200910134923.GR6583@casper.infradead.org>
在 2020/9/10 下午9:49, Matthew Wilcox 写道:
> On Mon, Aug 24, 2020 at 08:54:39PM +0800, Alex Shi wrote:
>> 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.
>
> What stats are you talking about here?
Hi Matthew,
Thanks for comments!
like __dec_node_page_state(head, NR_SHMEM_THPS); will have preemptive warning...
>
>> +++ b/mm/huge_memory.c
>> @@ -2397,7 +2397,7 @@ 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)
>
> Please don't change this whitespace. It's really annoying having to
> adjust the whitespace when renaming a function. Just two tabs indentation
> to give a clear separation of arguments from code is fine.
>
>
> How about this patch instead? It occurred to me we already have
> perfectly good infrastructure to track whether or not interrupts are
> already disabled, and so we should use that instead of ensuring that
> interrupts are disabled, or tracking that ourselves.
So your proposal looks like;
1, xa_lock_irq(&mapping->i_pages); (optional)
2, spin_lock_irqsave(&ds_queue->split_queue_lock, flags);
3, spin_lock_irqsave(&pgdat->lru_lock, flags);
Is there meaningful for the 2nd and 3rd flags?
IIRC, I had a similar proposal as your, the flags used in xa_lock_irqsave(),
but objected by Hugh.
Thanks
Alex
>
> But I may have missed something else that's relying on having
> interrupts disabled. Please check carefully.
>
> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> index 2ccff8472cd4..74cae6c032f9 100644
> --- a/mm/huge_memory.c
> +++ b/mm/huge_memory.c
> @@ -2376,17 +2376,16 @@ 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);
> struct lruvec *lruvec;
> struct address_space *swap_cache = NULL;
> unsigned long offset = 0;
> + unsigned long flags;
> int i;
>
> - lruvec = mem_cgroup_page_lruvec(head, pgdat);
> -
> /* complete memcg works before add pages to LRU */
> mem_cgroup_split_huge_fixup(head);
>
> @@ -2395,9 +2394,13 @@ static void __split_huge_page(struct page *page, struct list_head *list,
>
> offset = swp_offset(entry);
> swap_cache = swap_address_space(entry);
> - xa_lock(&swap_cache->i_pages);
> + xa_lock_irq(&swap_cache->i_pages);
> }
>
> + /* prevent PageLRU to go away from under us, and freeze lru stats */
> + spin_lock_irqsave(&pgdat->lru_lock, flags);
> + 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 */
> @@ -2417,6 +2420,7 @@ static void __split_huge_page(struct page *page, struct list_head *list,
> }
>
> ClearPageCompound(head);
> + spin_unlock_irqrestore(&pgdat->lru_lock, flags);
>
> split_page_owner(head, HPAGE_PMD_ORDER);
>
> @@ -2425,18 +2429,16 @@ static void __split_huge_page(struct page *page, struct list_head *list,
> /* Additional pin to swap cache */
> if (PageSwapCache(head)) {
> page_ref_add(head, 2);
> - xa_unlock(&swap_cache->i_pages);
> + xa_unlock_irq(&swap_cache->i_pages);
> } else {
> page_ref_inc(head);
> }
> } else {
> /* Additional pin to page cache */
> page_ref_add(head, 2);
> - xa_unlock(&head->mapping->i_pages);
> + xa_unlock_irq(&head->mapping->i_pages);
> }
>
> - spin_unlock_irqrestore(&pgdat->lru_lock, flags);
> -
> remap_page(head);
>
> for (i = 0; i < HPAGE_PMD_NR; i++) {
> @@ -2574,7 +2576,6 @@ 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;
> @@ -2640,9 +2641,6 @@ 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);
> -
> if (mapping) {
> XA_STATE(xas, &mapping->i_pages, page_index(head));
>
> @@ -2650,13 +2648,13 @@ int split_huge_page_to_list(struct page *page, struct list_head *list)
> * Check if the head page is present in page cache.
> * We assume all tail are present too, if head is there.
> */
> - xa_lock(&mapping->i_pages);
> + xa_lock_irq(&mapping->i_pages);
> if (xas_load(&xas) != head)
> goto fail;
> }
>
> /* Prevent deferred_split_scan() touching ->_refcount */
> - spin_lock(&ds_queue->split_queue_lock);
> + spin_lock_irqsave(&ds_queue->split_queue_lock, flags);
> count = page_count(head);
> mapcount = total_mapcount(head);
> if (!mapcount && page_ref_freeze(head, 1 + extra_pins)) {
> @@ -2664,7 +2662,7 @@ int split_huge_page_to_list(struct page *page, struct list_head *list)
> ds_queue->split_queue_len--;
> list_del(page_deferred_list(head));
> }
> - spin_unlock(&ds_queue->split_queue_lock);
> + spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags);
> if (mapping) {
> if (PageSwapBacked(head))
> __dec_node_page_state(head, NR_SHMEM_THPS);
> @@ -2672,7 +2670,7 @@ 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) };
>
> @@ -2688,10 +2686,9 @@ int split_huge_page_to_list(struct page *page, struct list_head *list)
> dump_page(page, "total_mapcount(head) > 0");
> BUG();
> }
> - spin_unlock(&ds_queue->split_queue_lock);
> + spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags);
> fail: if (mapping)
> - xa_unlock(&mapping->i_pages);
> - spin_unlock_irqrestore(&pgdata->lru_lock, flags);
> + xa_unlock_irq(&mapping->i_pages);
> remap_page(head);
> ret = -EBUSY;
> }
>
next prev parent reply other threads:[~2020-09-11 3:39 UTC|newest]
Thread overview: 102+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-24 12:54 [PATCH v18 00/32] per memcg lru_lock Alex Shi
2020-08-24 12:54 ` [PATCH v18 01/32] mm/memcg: warning on !memcg after readahead page charged Alex Shi
2020-08-24 12:54 ` [PATCH v18 02/32] mm/memcg: bail out early from swap accounting when memcg is disabled Alex Shi
2020-08-24 12:54 ` [PATCH v18 03/32] mm/thp: move lru_add_page_tail func to huge_memory.c Alex Shi
2020-08-24 12:54 ` [PATCH v18 04/32] mm/thp: clean up lru_add_page_tail Alex Shi
2020-08-24 12:54 ` [PATCH v18 05/32] mm/thp: remove code path which never got into Alex Shi
2020-08-24 12:54 ` [PATCH v18 06/32] mm/thp: narrow lru locking Alex Shi
2020-09-10 13:49 ` Matthew Wilcox
2020-09-11 3:37 ` Alex Shi [this message]
2020-09-13 15:27 ` Matthew Wilcox
2020-09-19 1:00 ` Hugh Dickins
2020-08-24 12:54 ` [PATCH v18 07/32] mm/swap.c: stop deactivate_file_page if page not on lru Alex Shi
2020-08-24 12:54 ` [PATCH v18 08/32] mm/vmscan: remove unnecessary lruvec adding Alex Shi
2020-08-24 12:54 ` [PATCH v18 09/32] mm/page_idle: no unlikely double check for idle page counting Alex Shi
2020-08-24 12:54 ` [PATCH v18 10/32] mm/compaction: rename compact_deferred as compact_should_defer Alex Shi
2020-08-24 12:54 ` [PATCH v18 11/32] mm/memcg: add debug checking in lock_page_memcg Alex Shi
2020-08-24 12:54 ` [PATCH v18 12/32] mm/memcg: optimize mem_cgroup_page_lruvec Alex Shi
2020-08-24 12:54 ` [PATCH v18 13/32] mm/swap.c: fold vm event PGROTATED into pagevec_move_tail_fn Alex Shi
2020-08-24 12:54 ` [PATCH v18 14/32] mm/lru: move lru_lock holding in func lru_note_cost_page Alex Shi
2020-08-24 12:54 ` [PATCH v18 15/32] mm/lru: move lock into lru_note_cost Alex Shi
2020-09-21 21:36 ` Hugh Dickins
2020-09-21 22:03 ` Hugh Dickins
2020-09-22 3:39 ` Alex Shi
2020-09-22 3:38 ` Alex Shi
2020-08-24 12:54 ` [PATCH v18 16/32] mm/lru: introduce TestClearPageLRU Alex Shi
2020-09-21 23:16 ` Hugh Dickins
2020-09-22 3:53 ` Alex Shi
2020-08-24 12:54 ` [PATCH v18 17/32] mm/compaction: do page isolation first in compaction Alex Shi
2020-09-21 23:49 ` Hugh Dickins
2020-09-22 4:57 ` Alex Shi
2020-08-24 12:54 ` [PATCH v18 18/32] mm/thp: add tail pages into lru anyway in split_huge_page() Alex Shi
2020-08-24 12:54 ` [PATCH v18 19/32] mm/swap.c: serialize memcg changes in pagevec_lru_move_fn Alex Shi
2020-09-22 0:42 ` Hugh Dickins
2020-09-22 5:00 ` Alex Shi
2020-08-24 12:54 ` [PATCH v18 20/32] mm/lru: replace pgdat lru_lock with lruvec lock Alex Shi
2020-09-22 5:27 ` Hugh Dickins
2020-09-22 8:58 ` Alex Shi
2020-08-24 12:54 ` [PATCH v18 21/32] mm/lru: introduce the relock_page_lruvec function Alex Shi
2020-09-22 5:40 ` Hugh Dickins
2020-08-24 12:54 ` [PATCH v18 22/32] mm/vmscan: use relock for move_pages_to_lru Alex Shi
2020-09-22 5:44 ` Hugh Dickins
2020-09-23 1:55 ` Alex Shi
2020-08-24 12:54 ` [PATCH v18 23/32] mm/lru: revise the comments of lru_lock Alex Shi
2020-09-22 5:48 ` Hugh Dickins
2020-08-24 12:54 ` [PATCH v18 24/32] mm/pgdat: remove pgdat lru_lock Alex Shi
2020-09-22 5:53 ` Hugh Dickins
2020-09-23 1:55 ` Alex Shi
2020-08-24 12:54 ` [PATCH v18 25/32] mm/mlock: remove lru_lock on TestClearPageMlocked in munlock_vma_page Alex Shi
2020-08-26 5:52 ` Alex Shi
2020-09-22 6:13 ` Hugh Dickins
2020-09-23 1:58 ` Alex Shi
2020-08-24 12:54 ` [PATCH v18 26/32] mm/mlock: remove __munlock_isolate_lru_page Alex Shi
2020-08-24 12:55 ` [PATCH v18 27/32] mm/swap.c: optimizing __pagevec_lru_add lru_lock Alex Shi
2020-08-26 9:07 ` Alex Shi
2020-08-24 12:55 ` [PATCH v18 28/32] mm/compaction: Drop locked from isolate_migratepages_block Alex Shi
2020-08-24 12:55 ` [PATCH v18 29/32] mm: Identify compound pages sooner in isolate_migratepages_block Alex Shi
2020-08-24 12:55 ` [PATCH v18 30/32] mm: Drop use of test_and_set_skip in favor of just setting skip Alex Shi
2020-08-24 12:55 ` [PATCH v18 31/32] mm: Add explicit page decrement in exception path for isolate_lru_pages Alex Shi
2020-09-09 1:01 ` Matthew Wilcox
2020-09-09 15:43 ` Alexander Duyck
2020-09-09 17:07 ` Matthew Wilcox
2020-09-09 18:24 ` Hugh Dickins
2020-09-09 20:15 ` Matthew Wilcox
2020-09-09 21:05 ` Hugh Dickins
2020-09-09 21:17 ` Alexander Duyck
2020-08-24 12:55 ` [PATCH v18 32/32] mm: Split release_pages work into 3 passes Alex Shi
2020-08-24 18:42 ` [PATCH v18 00/32] per memcg lru_lock Andrew Morton
2020-08-24 20:24 ` Hugh Dickins
2020-08-25 1:56 ` Daniel Jordan
2020-08-25 3:26 ` Alex Shi
2020-08-25 11:39 ` Matthew Wilcox
2020-08-26 1:19 ` Daniel Jordan
2020-08-26 8:59 ` Alex Shi
2020-08-28 1:40 ` Daniel Jordan
2020-08-28 5:22 ` Alex Shi
2020-09-09 2:44 ` Aaron Lu
2020-09-09 11:40 ` Michal Hocko
2020-08-25 8:52 ` Alex Shi
2020-08-25 13:00 ` Alex Shi
2020-08-27 7:01 ` Hugh Dickins
2020-08-27 12:20 ` Race between freeing and waking page Matthew Wilcox
2020-09-08 23:41 ` [PATCH v18 00/32] per memcg lru_lock: reviews Hugh Dickins
2020-09-09 2:24 ` Wei Yang
2020-09-09 15:08 ` Alex Shi
2020-09-09 23:16 ` Hugh Dickins
2020-09-11 2:50 ` Alex Shi
2020-09-12 2:13 ` Hugh Dickins
2020-09-13 14:21 ` Alex Shi
2020-09-15 8:21 ` Hugh Dickins
2020-09-15 16:58 ` Daniel Jordan
2020-09-16 12:44 ` Alex Shi
2020-09-17 2:37 ` Alex Shi
2020-09-17 14:35 ` Daniel Jordan
2020-09-17 15:39 ` Alexander Duyck
2020-09-17 16:48 ` Daniel Jordan
2020-09-12 8:38 ` Hugh Dickins
2020-09-13 14:22 ` Alex Shi
2020-09-09 16:11 ` Alexander Duyck
2020-09-10 0:32 ` Hugh Dickins
2020-09-10 14:24 ` Alexander Duyck
2020-09-12 5:12 ` Hugh Dickins
2020-08-25 7:21 ` [PATCH v18 00/32] per memcg lru_lock Michal Hocko
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