From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alex Shi Subject: [PATCH v19 13/20] mm/mlock: remove lru_lock on TestClearPageMlocked Date: Thu, 24 Sep 2020 11:28:28 +0800 Message-ID: <1600918115-22007-14-git-send-email-alex.shi@linux.alibaba.com> References: <1600918115-22007-1-git-send-email-alex.shi@linux.alibaba.com> Return-path: In-Reply-To: <1600918115-22007-1-git-send-email-alex.shi@linux.alibaba.com> List-ID: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit 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, aaron.lwe@gmail.com Cc: "Kirill A. Shutemov" , Vlastimil Babka In the func munlock_vma_page, comments mentained lru_lock needed for serialization with split_huge_pages. But the page must be PageLocked as well as pages in split_huge_page series funcs. Thus the PageLocked is enough to serialize both funcs. Further more, Hugh Dickins pointed: before splitting in split_huge_page_to_list, the page was unmap_page() to remove pmd/ptes which protect the page from munlock. Thus, no needs to guard __split_huge_page_tail for mlock clean, just keep the lru_lock there for isolation purpose. LKP found a preempt issue on __mod_zone_page_state which need change to mod_zone_page_state. Thanks! Signed-off-by: Alex Shi Acked-by: Hugh Dickins Cc: Kirill A. Shutemov Cc: Vlastimil Babka Cc: Andrew Morton Cc: linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org --- mm/mlock.c | 26 +++++--------------------- 1 file changed, 5 insertions(+), 21 deletions(-) diff --git a/mm/mlock.c b/mm/mlock.c index 884b1216da6a..796c726a0407 100644 --- a/mm/mlock.c +++ b/mm/mlock.c @@ -187,40 +187,24 @@ static void __munlock_isolation_failed(struct page *page) unsigned int munlock_vma_page(struct page *page) { int nr_pages; - pg_data_t *pgdat = page_pgdat(page); /* For try_to_munlock() and to serialize with page migration */ BUG_ON(!PageLocked(page)); - VM_BUG_ON_PAGE(PageTail(page), page); - /* - * Serialize with any parallel __split_huge_page_refcount() which - * might otherwise copy PageMlocked to part of the tail pages before - * we clear it in the head page. It also stabilizes thp_nr_pages(). - */ - spin_lock_irq(&pgdat->lru_lock); - if (!TestClearPageMlocked(page)) { /* Potentially, PTE-mapped THP: do not skip the rest PTEs */ - nr_pages = 1; - goto unlock_out; + return 0; } nr_pages = thp_nr_pages(page); - __mod_zone_page_state(page_zone(page), NR_MLOCK, -nr_pages); + mod_zone_page_state(page_zone(page), NR_MLOCK, -nr_pages); - if (__munlock_isolate_lru_page(page, true)) { - spin_unlock_irq(&pgdat->lru_lock); + if (!isolate_lru_page(page)) __munlock_isolated_page(page); - goto out; - } - __munlock_isolation_failed(page); - -unlock_out: - spin_unlock_irq(&pgdat->lru_lock); + else + __munlock_isolation_failed(page); -out: return nr_pages - 1; } -- 1.8.3.1