| Message ID | 1604566549-62481-13-git-send-email-alex.shi@linux.alibaba.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | per memcg lru lock | expand |
On 11/5/20 9:55 AM, Alex Shi wrote: > 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 <alex.shi@linux.alibaba.com> > Acked-by: Hugh Dickins <hughd@google.com> > Acked-by: Johannes Weiner <hannes@cmpxchg.org> > Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> > Cc: Vlastimil Babka <vbabka@suse.cz> > Cc: Andrew Morton <akpm@linux-foundation.org> > Cc: linux-mm@kvack.org > Cc: linux-kernel@vger.kernel.org Acked-by: Vlastimil Babka <vbabka@suse.cz> Nit below: > --- > 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 */ Now the reasons for locking are expanded? > 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; > } > >
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; }