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Date: Fri, 17 Jul 2020 15:03:24 -0700
From: Alexander Duyck <alexander.duyck@...il.com>
To: Alex Shi <alex.shi@...ux.alibaba.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>,
Mel Gorman <mgorman@...hsingularity.net>,
Tejun Heo <tj@...nel.org>, Hugh Dickins <hughd@...gle.com>,
Konstantin Khlebnikov <khlebnikov@...dex-team.ru>,
Daniel Jordan <daniel.m.jordan@...cle.com>,
Yang Shi <yang.shi@...ux.alibaba.com>,
Matthew Wilcox <willy@...radead.org>,
Johannes Weiner <hannes@...xchg.org>,
kbuild test robot <lkp@...el.com>,
linux-mm <linux-mm@...ck.org>,
LKML <linux-kernel@...r.kernel.org>, cgroups@...r.kernel.org,
Shakeel Butt <shakeelb@...gle.com>,
Joonsoo Kim <iamjoonsoo.kim@....com>,
Wei Yang <richard.weiyang@...il.com>,
"Kirill A. Shutemov" <kirill@...temov.name>,
Thomas Gleixner <tglx@...utronix.de>,
Andrey Ryabinin <aryabinin@...tuozzo.com>
Subject: Re: [PATCH v16 19/22] mm/lru: introduce the relock_page_lruvec function
On Fri, Jul 10, 2020 at 5:59 PM Alex Shi <alex.shi@...ux.alibaba.com> wrote:
>
> Use this new function to replace repeated same code, no func change.
>
> Signed-off-by: Alex Shi <alex.shi@...ux.alibaba.com>
> Cc: Johannes Weiner <hannes@...xchg.org>
> Cc: Andrew Morton <akpm@...ux-foundation.org>
> Cc: Thomas Gleixner <tglx@...utronix.de>
> Cc: Andrey Ryabinin <aryabinin@...tuozzo.com>
> Cc: Matthew Wilcox <willy@...radead.org>
> Cc: Mel Gorman <mgorman@...hsingularity.net>
> Cc: Konstantin Khlebnikov <khlebnikov@...dex-team.ru>
> Cc: Hugh Dickins <hughd@...gle.com>
> Cc: Tejun Heo <tj@...nel.org>
> Cc: linux-kernel@...r.kernel.org
> Cc: cgroups@...r.kernel.org
> Cc: linux-mm@...ck.org
> ---
> mm/mlock.c | 9 +--------
> mm/swap.c | 33 +++++++--------------------------
> mm/vmscan.c | 8 +-------
> 3 files changed, 9 insertions(+), 41 deletions(-)
>
> diff --git a/mm/mlock.c b/mm/mlock.c
> index cb23a0c2cfbf..4f40fc091cf9 100644
> --- a/mm/mlock.c
> +++ b/mm/mlock.c
> @@ -289,17 +289,10 @@ static void __munlock_pagevec(struct pagevec *pvec, struct zone *zone)
> /* Phase 1: page isolation */
> for (i = 0; i < nr; i++) {
> struct page *page = pvec->pages[i];
> - struct lruvec *new_lruvec;
> bool clearlru;
>
> clearlru = TestClearPageLRU(page);
> -
> - new_lruvec = mem_cgroup_page_lruvec(page, page_pgdat(page));
> - if (new_lruvec != lruvec) {
> - if (lruvec)
> - unlock_page_lruvec_irq(lruvec);
> - lruvec = lock_page_lruvec_irq(page);
> - }
> + lruvec = relock_page_lruvec_irq(page, lruvec);
>
> if (!TestClearPageMlocked(page)) {
> delta_munlocked++;
> diff --git a/mm/swap.c b/mm/swap.c
> index 129c532357a4..9fb906fbaed5 100644
> --- a/mm/swap.c
> +++ b/mm/swap.c
> @@ -209,19 +209,12 @@ static void pagevec_lru_move_fn(struct pagevec *pvec,
>
> for (i = 0; i < pagevec_count(pvec); i++) {
> struct page *page = pvec->pages[i];
> - struct lruvec *new_lruvec;
> -
> - new_lruvec = mem_cgroup_page_lruvec(page, page_pgdat(page));
> - if (lruvec != new_lruvec) {
> - if (lruvec)
> - unlock_page_lruvec_irqrestore(lruvec, flags);
> - lruvec = lock_page_lruvec_irqsave(page, &flags);
> - }
>
> /* block memcg migration during page moving between lru */
> if (!TestClearPageLRU(page))
> continue;
>
> + lruvec = relock_page_lruvec_irqsave(page, lruvec, &flags);
> (*move_fn)(page, lruvec);
>
> SetPageLRU(page);
So looking at this I realize that patch 18 probably should have
ordered this the same way with the TestClearPageLRU happening before
you fetched the new_lruvec. Otherwise I think you are potentially
exposed to the original issue you were fixing the the previous patch
that added the call to TestClearPageLRU.
> @@ -866,17 +859,12 @@ void release_pages(struct page **pages, int nr)
> }
>
> if (PageLRU(page)) {
> - struct lruvec *new_lruvec;
> -
> - new_lruvec = mem_cgroup_page_lruvec(page,
> - page_pgdat(page));
> - if (new_lruvec != lruvec) {
> - if (lruvec)
> - unlock_page_lruvec_irqrestore(lruvec,
> - flags);
> + struct lruvec *pre_lruvec = lruvec;
> +
> + lruvec = relock_page_lruvec_irqsave(page, lruvec,
> + &flags);
> + if (pre_lruvec != lruvec)
So this doesn't really read right. I suppose "pre_lruvec" should
probably be "prev_lruvec" since I assume you mean "previous" not
"before".
> lock_batch = 0;
> - lruvec = lock_page_lruvec_irqsave(page, &flags);
> - }
>
> __ClearPageLRU(page);
> del_page_from_lru_list(page, lruvec, page_off_lru(page));
> @@ -982,15 +970,8 @@ void __pagevec_lru_add(struct pagevec *pvec)
>
> for (i = 0; i < pagevec_count(pvec); i++) {
> struct page *page = pvec->pages[i];
> - struct lruvec *new_lruvec;
> -
> - new_lruvec = mem_cgroup_page_lruvec(page, page_pgdat(page));
> - if (lruvec != new_lruvec) {
> - if (lruvec)
> - unlock_page_lruvec_irqrestore(lruvec, flags);
> - lruvec = lock_page_lruvec_irqsave(page, &flags);
> - }
>
> + lruvec = relock_page_lruvec_irqsave(page, lruvec, &flags);
> __pagevec_lru_add_fn(page, lruvec);
> }
> if (lruvec)
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index 168c1659e430..bdb53a678e7e 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -4292,15 +4292,9 @@ void check_move_unevictable_pages(struct pagevec *pvec)
>
> for (i = 0; i < pvec->nr; i++) {
> struct page *page = pvec->pages[i];
> - struct lruvec *new_lruvec;
>
> pgscanned++;
> - new_lruvec = mem_cgroup_page_lruvec(page, page_pgdat(page));
> - if (lruvec != new_lruvec) {
> - if (lruvec)
> - unlock_page_lruvec_irq(lruvec);
> - lruvec = lock_page_lruvec_irq(page);
> - }
> + lruvec = relock_page_lruvec_irq(page, lruvec);
>
> if (!PageLRU(page) || !PageUnevictable(page))
> continue;
> --
> 1.8.3.1
>
>
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