The func is only used in huge_memory.c, defining it in other file with a CONFIG_TRANSPARENT_HUGEPAGE macro restrict just looks weird. Let's move it THP. And make it static as Hugh Dickin suggested. Signed-off-by: Alex Shi <alex.shi@linux.alibaba.com> Reviewed-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Matthew Wilcox <willy@infradead.org> Cc: Hugh Dickins <hughd@google.com> Cc: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org --- include/linux/swap.h | 2 -- mm/huge_memory.c | 30 ++++++++++++++++++++++++++++++ mm/swap.c | 33 --------------------------------- 3 files changed, 30 insertions(+), 35 deletions(-) diff --git a/include/linux/swap.h b/include/linux/swap.h index 661046994db4..43e6b3458f58 100644 --- a/include/linux/swap.h +++ b/include/linux/swap.h @@ -338,8 +338,6 @@ extern void lru_note_cost(struct lruvec *lruvec, bool file, unsigned int nr_pages); extern void lru_note_cost_page(struct page *); extern void lru_cache_add(struct page *); -extern void lru_add_page_tail(struct page *page, struct page *page_tail, - struct lruvec *lruvec, struct list_head *head); extern void activate_page(struct page *); extern void mark_page_accessed(struct page *); extern void lru_add_drain(void); diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 90733cefa528..bc905e7079bf 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -2315,6 +2315,36 @@ static void remap_page(struct page *page) } } +static void lru_add_page_tail(struct page *page, struct page *page_tail, + struct lruvec *lruvec, struct list_head *list) +{ + VM_BUG_ON_PAGE(!PageHead(page), page); + VM_BUG_ON_PAGE(PageCompound(page_tail), page); + VM_BUG_ON_PAGE(PageLRU(page_tail), page); + lockdep_assert_held(&lruvec_pgdat(lruvec)->lru_lock); + + if (!list) + SetPageLRU(page_tail); + + if (likely(PageLRU(page))) + list_add_tail(&page_tail->lru, &page->lru); + else if (list) { + /* page reclaim is reclaiming a huge page */ + get_page(page_tail); + list_add_tail(&page_tail->lru, list); + } else { + /* + * Head page has not yet been counted, as an hpage, + * so we must account for each subpage individually. + * + * Put page_tail on the list at the correct position + * so they all end up in order. + */ + add_page_to_lru_list_tail(page_tail, lruvec, + page_lru(page_tail)); + } +} + static void __split_huge_page_tail(struct page *head, int tail, struct lruvec *lruvec, struct list_head *list) { diff --git a/mm/swap.c b/mm/swap.c index d16d65d9b4e0..c674fb441fe9 100644 --- a/mm/swap.c +++ b/mm/swap.c @@ -935,39 +935,6 @@ void __pagevec_release(struct pagevec *pvec) } EXPORT_SYMBOL(__pagevec_release); -#ifdef CONFIG_TRANSPARENT_HUGEPAGE -/* used by __split_huge_page_refcount() */ -void lru_add_page_tail(struct page *page, struct page *page_tail, - struct lruvec *lruvec, struct list_head *list) -{ - VM_BUG_ON_PAGE(!PageHead(page), page); - VM_BUG_ON_PAGE(PageCompound(page_tail), page); - VM_BUG_ON_PAGE(PageLRU(page_tail), page); - lockdep_assert_held(&lruvec_pgdat(lruvec)->lru_lock); - - if (!list) - SetPageLRU(page_tail); - - if (likely(PageLRU(page))) - list_add_tail(&page_tail->lru, &page->lru); - else if (list) { - /* page reclaim is reclaiming a huge page */ - get_page(page_tail); - list_add_tail(&page_tail->lru, list); - } else { - /* - * Head page has not yet been counted, as an hpage, - * so we must account for each subpage individually. - * - * Put page_tail on the list at the correct position - * so they all end up in order. - */ - add_page_to_lru_list_tail(page_tail, lruvec, - page_lru(page_tail)); - } -} -#endif /* CONFIG_TRANSPARENT_HUGEPAGE */ - static void __pagevec_lru_add_fn(struct page *page, struct lruvec *lruvec, void *arg) { -- 1.8.3.1
Since the first parameter is only used by head page, it's better to make it explicit. Signed-off-by: Alex Shi <alex.shi@linux.alibaba.com> Reviewed-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Matthew Wilcox <willy@infradead.org> Cc: Hugh Dickins <hughd@google.com> Cc: linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org --- mm/huge_memory.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) diff --git a/mm/huge_memory.c b/mm/huge_memory.c index bc905e7079bf..8cecd39bd8b7 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -2315,19 +2315,19 @@ static void remap_page(struct page *page) } } -static void lru_add_page_tail(struct page *page, struct page *page_tail, +static void lru_add_page_tail(struct page *head, struct page *page_tail, struct lruvec *lruvec, struct list_head *list) { - VM_BUG_ON_PAGE(!PageHead(page), page); - VM_BUG_ON_PAGE(PageCompound(page_tail), page); - VM_BUG_ON_PAGE(PageLRU(page_tail), page); + VM_BUG_ON_PAGE(!PageHead(head), head); + VM_BUG_ON_PAGE(PageCompound(page_tail), head); + VM_BUG_ON_PAGE(PageLRU(page_tail), head); lockdep_assert_held(&lruvec_pgdat(lruvec)->lru_lock); if (!list) SetPageLRU(page_tail); - if (likely(PageLRU(page))) - list_add_tail(&page_tail->lru, &page->lru); + if (likely(PageLRU(head))) + list_add_tail(&page_tail->lru, &head->lru); else if (list) { /* page reclaim is reclaiming a huge page */ get_page(page_tail); -- 1.8.3.1
split_huge_page() will never call on a page which isn't on lru list, so this code never got a chance to run, and should not be run, to add tail pages on a lru list which head page isn't there. Although the bug was never triggered, it'better be removed for code correctness. BTW, it looks better to have a WARN() set in the wrong path, but the path will be changed in incoming new page isolation func. So just save it now. Signed-off-by: Alex Shi <alex.shi@linux.alibaba.com> Reviewed-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Kirill A. Shutemov <kirill@shutemov.name> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Matthew Wilcox <willy@infradead.org> Cc: Hugh Dickins <hughd@google.com> Cc: linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org --- mm/huge_memory.c | 10 ---------- 1 file changed, 10 deletions(-) diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 8cecd39bd8b7..dfe7378ab4be 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -2332,16 +2332,6 @@ static void lru_add_page_tail(struct page *head, struct page *page_tail, /* page reclaim is reclaiming a huge page */ get_page(page_tail); list_add_tail(&page_tail->lru, list); - } else { - /* - * Head page has not yet been counted, as an hpage, - * so we must account for each subpage individually. - * - * Put page_tail on the list at the correct position - * so they all end up in order. - */ - add_page_to_lru_list_tail(page_tail, lruvec, - page_lru(page_tail)); } } -- 1.8.3.1
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. 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(). Signed-off-by: Alex Shi <alex.shi@linux.alibaba.com> Signed-off-by: Wei Yang <richard.weiyang@gmail.com> Reviewed-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.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 dfe7378ab4be..070480e66bf4 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -2398,7 +2398,7 @@ 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); @@ -2407,8 +2407,6 @@ static void __split_huge_page(struct page *page, struct list_head *list, unsigned long offset = 0; int i; - lruvec = mem_cgroup_page_lruvec(head, pgdat); - /* complete memcg works before add pages to LRU */ mem_cgroup_split_huge_fixup(head); @@ -2420,6 +2418,11 @@ 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 = 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 */ @@ -2439,6 +2442,8 @@ 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, HPAGE_PMD_ORDER); @@ -2456,8 +2461,7 @@ 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); @@ -2596,12 +2600,10 @@ 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); @@ -2662,9 +2664,8 @@ 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)); @@ -2694,7 +2695,7 @@ 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) }; @@ -2713,7 +2714,7 @@ 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); ret = -EBUSY; } -- 1.8.3.1
Hi Andrew,
This patchset is just cleanup and get reviewed by Kirill, is it cath up 5.9?
Thanks
Alex
在 2020/8/1 下午12:09, Alex Shi 写道:
> The func is only used in huge_memory.c, defining it in other file with a
> CONFIG_TRANSPARENT_HUGEPAGE macro restrict just looks weird.
>
> Let's move it THP. And make it static as Hugh Dickin suggested.
>
> Signed-off-by: Alex Shi <alex.shi@linux.alibaba.com>
> Reviewed-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Johannes Weiner <hannes@cmpxchg.org>
> Cc: Matthew Wilcox <willy@infradead.org>
> Cc: Hugh Dickins <hughd@google.com>
> Cc: linux-kernel@vger.kernel.org
> Cc: linux-mm@kvack.org
> ---
> include/linux/swap.h | 2 --
> mm/huge_memory.c | 30 ++++++++++++++++++++++++++++++
> mm/swap.c | 33 ---------------------------------
> 3 files changed, 30 insertions(+), 35 deletions(-)
>
> diff --git a/include/linux/swap.h b/include/linux/swap.h
> index 661046994db4..43e6b3458f58 100644
> --- a/include/linux/swap.h
> +++ b/include/linux/swap.h
> @@ -338,8 +338,6 @@ extern void lru_note_cost(struct lruvec *lruvec, bool file,
> unsigned int nr_pages);
> extern void lru_note_cost_page(struct page *);
> extern void lru_cache_add(struct page *);
> -extern void lru_add_page_tail(struct page *page, struct page *page_tail,
> - struct lruvec *lruvec, struct list_head *head);
> extern void activate_page(struct page *);
> extern void mark_page_accessed(struct page *);
> extern void lru_add_drain(void);
> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> index 90733cefa528..bc905e7079bf 100644
> --- a/mm/huge_memory.c
> +++ b/mm/huge_memory.c
> @@ -2315,6 +2315,36 @@ static void remap_page(struct page *page)
> }
> }
>
> +static void lru_add_page_tail(struct page *page, struct page *page_tail,
> + struct lruvec *lruvec, struct list_head *list)
> +{
> + VM_BUG_ON_PAGE(!PageHead(page), page);
> + VM_BUG_ON_PAGE(PageCompound(page_tail), page);
> + VM_BUG_ON_PAGE(PageLRU(page_tail), page);
> + lockdep_assert_held(&lruvec_pgdat(lruvec)->lru_lock);
> +
> + if (!list)
> + SetPageLRU(page_tail);
> +
> + if (likely(PageLRU(page)))
> + list_add_tail(&page_tail->lru, &page->lru);
> + else if (list) {
> + /* page reclaim is reclaiming a huge page */
> + get_page(page_tail);
> + list_add_tail(&page_tail->lru, list);
> + } else {
> + /*
> + * Head page has not yet been counted, as an hpage,
> + * so we must account for each subpage individually.
> + *
> + * Put page_tail on the list at the correct position
> + * so they all end up in order.
> + */
> + add_page_to_lru_list_tail(page_tail, lruvec,
> + page_lru(page_tail));
> + }
> +}
> +
> static void __split_huge_page_tail(struct page *head, int tail,
> struct lruvec *lruvec, struct list_head *list)
> {
> diff --git a/mm/swap.c b/mm/swap.c
> index d16d65d9b4e0..c674fb441fe9 100644
> --- a/mm/swap.c
> +++ b/mm/swap.c
> @@ -935,39 +935,6 @@ void __pagevec_release(struct pagevec *pvec)
> }
> EXPORT_SYMBOL(__pagevec_release);
>
> -#ifdef CONFIG_TRANSPARENT_HUGEPAGE
> -/* used by __split_huge_page_refcount() */
> -void lru_add_page_tail(struct page *page, struct page *page_tail,
> - struct lruvec *lruvec, struct list_head *list)
> -{
> - VM_BUG_ON_PAGE(!PageHead(page), page);
> - VM_BUG_ON_PAGE(PageCompound(page_tail), page);
> - VM_BUG_ON_PAGE(PageLRU(page_tail), page);
> - lockdep_assert_held(&lruvec_pgdat(lruvec)->lru_lock);
> -
> - if (!list)
> - SetPageLRU(page_tail);
> -
> - if (likely(PageLRU(page)))
> - list_add_tail(&page_tail->lru, &page->lru);
> - else if (list) {
> - /* page reclaim is reclaiming a huge page */
> - get_page(page_tail);
> - list_add_tail(&page_tail->lru, list);
> - } else {
> - /*
> - * Head page has not yet been counted, as an hpage,
> - * so we must account for each subpage individually.
> - *
> - * Put page_tail on the list at the correct position
> - * so they all end up in order.
> - */
> - add_page_to_lru_list_tail(page_tail, lruvec,
> - page_lru(page_tail));
> - }
> -}
> -#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
> -
> static void __pagevec_lru_add_fn(struct page *page, struct lruvec *lruvec,
> void *arg)
> {
>
You're playing games with separating interrupt disabling from spinlocks.
Have you got any feedback from -rt people on this?
On Sat, Aug 01, 2020 at 12:09:17PM +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.
>
> 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().
>
> Signed-off-by: Alex Shi <alex.shi@linux.alibaba.com>
> Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
> Reviewed-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.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 dfe7378ab4be..070480e66bf4 100644
> --- a/mm/huge_memory.c
> +++ b/mm/huge_memory.c
> @@ -2398,7 +2398,7 @@ 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);
> @@ -2407,8 +2407,6 @@ static void __split_huge_page(struct page *page, struct list_head *list,
> unsigned long offset = 0;
> int i;
>
> - lruvec = mem_cgroup_page_lruvec(head, pgdat);
> -
> /* complete memcg works before add pages to LRU */
> mem_cgroup_split_huge_fixup(head);
>
> @@ -2420,6 +2418,11 @@ 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 = 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 */
> @@ -2439,6 +2442,8 @@ 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, HPAGE_PMD_ORDER);
>
> @@ -2456,8 +2461,7 @@ 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);
>
> @@ -2596,12 +2600,10 @@ 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);
> @@ -2662,9 +2664,8 @@ 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));
>
> @@ -2694,7 +2695,7 @@ 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) };
>
> @@ -2713,7 +2714,7 @@ 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);
> ret = -EBUSY;
> }
> --
> 1.8.3.1
>
在 2020/8/2 下午7:09, Matthew Wilcox 写道:
> You're playing games with separating interrupt disabling from spinlocks.
> Have you got any feedback from -rt people on this?
Is there other suggestions to remove local_irq_disable?
Just check again on kernel/mm directory on linux-next. there are still
much local_irq_disable there.
Guess we need a final solution instead of block new one.
Thanks
Alex