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X-IronPort-AV: E=McAfee;i="6600,9927,10815"; a="438941782" X-IronPort-AV: E=Sophos;i="6.02,206,1688454000"; d="scan'208";a="438941782" Received: from fmsmga008.fm.intel.com ([10.253.24.58]) by orsmga104.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 27 Aug 2023 18:53:19 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10815"; a="803525904" X-IronPort-AV: E=Sophos;i="6.02,206,1688454000"; d="scan'208";a="803525904" Received: from yhuang6-desk2.sh.intel.com (HELO yhuang6-desk2.ccr.corp.intel.com) ([10.238.208.55]) by fmsmga008-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 27 Aug 2023 18:53:16 -0700 From: "Huang, Ying" To: Liu Shixin Cc: Yosry Ahmed , Michal Hocko , Johannes Weiner , "Roman Gushchin" , Shakeel Butt , Muchun Song , Andrew Morton , , , , Subject: Re: [PATCH v3] mm: vmscan: try to reclaim swapcache pages if no swap space References: <20230826034401.640861-1-liushixin2@huawei.com> Date: Mon, 28 Aug 2023 09:51:07 +0800 In-Reply-To: <20230826034401.640861-1-liushixin2@huawei.com> (Liu Shixin's message of "Sat, 26 Aug 2023 11:44:01 +0800") Message-ID: <87il9053zo.fsf@yhuang6-desk2.ccr.corp.intel.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/28.2 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=ascii X-Rspam-User: X-Stat-Signature: b6myajc39sdppy8hhfhqzrwozipkbx9m X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 52F7140003 X-HE-Tag: 1693187601-167878 X-HE-Meta: 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 F7Z85hqU hdhoYfYawK7QiexXNeQBzpKfWpQWkCUfA1QdzAv3WPM0+n6QMT2E+UHEDxfHuq1kaD993tWE+rXxLEn5gFiW94yj6zVKLrgkWxWElWFM/V+jw75bWRpjteCKtBAU1LVVZwHopjXdAVPwIqEhRJIxguvqiQA5t34ydXuJrxDfov8AoBtPCct3Zv1skutNSrUTWoIW/VB/0SbSKtn0JDui38Cm6lC3tHiXaGDvF X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Liu Shixin writes: > When spaces of swap devices are exhausted, only file pages can be reclaimed. > But there are still some swapcache pages in anon lru list. This can lead > to a premature out-of-memory. > > This problem can be fixed by checking number of swapcache pages in > can_reclaim_anon_pages(). > > Add a new bit swapcache_only in struct scan_control to skip isolating anon > pages that are not in the swap cache when only swap cache can be reclaimed. Better to describe how you test the patch and test results. > Signed-off-by: Liu Shixin > --- > include/linux/swap.h | 6 ++++++ > mm/memcontrol.c | 8 ++++++++ > mm/vmscan.c | 29 +++++++++++++++++++++++++++-- > 3 files changed, 41 insertions(+), 2 deletions(-) > > diff --git a/include/linux/swap.h b/include/linux/swap.h > index 456546443f1f..0318e918bfa4 100644 > --- a/include/linux/swap.h > +++ b/include/linux/swap.h > @@ -669,6 +669,7 @@ static inline void mem_cgroup_uncharge_swap(swp_entry_t entry, unsigned int nr_p > } > > extern long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg); > +extern long mem_cgroup_get_nr_swapcache_pages(struct mem_cgroup *memcg); > extern bool mem_cgroup_swap_full(struct folio *folio); > #else > static inline void mem_cgroup_swapout(struct folio *folio, swp_entry_t entry) > @@ -691,6 +692,11 @@ static inline long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg) > return get_nr_swap_pages(); > } > > +static inline long mem_cgroup_get_nr_swapcache_pages(struct mem_cgroup *memcg) > +{ > + return total_swapcache_pages(); > +} > + > static inline bool mem_cgroup_swap_full(struct folio *folio) > { > return vm_swap_full(); > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index e8ca4bdcb03c..c465829db92b 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -7567,6 +7567,14 @@ long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg) > return nr_swap_pages; > } > > +long mem_cgroup_get_nr_swapcache_pages(struct mem_cgroup *memcg) > +{ > + if (mem_cgroup_disabled()) > + return total_swapcache_pages(); > + > + return memcg_page_state(memcg, NR_SWAPCACHE); > +} > + > bool mem_cgroup_swap_full(struct folio *folio) > { > struct mem_cgroup *memcg; > diff --git a/mm/vmscan.c b/mm/vmscan.c > index 7c33c5b653ef..5cb4adf6642b 100644 > --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -137,6 +137,9 @@ struct scan_control { > /* Always discard instead of demoting to lower tier memory */ > unsigned int no_demotion:1; > > + /* Swap space is exhausted, only reclaim swapcache for anon LRU */ > + unsigned int swapcache_only:1; > + > /* Allocation order */ > s8 order; > > @@ -613,10 +616,20 @@ static inline bool can_reclaim_anon_pages(struct mem_cgroup *memcg, > */ > if (get_nr_swap_pages() > 0) > return true; > + /* Is there any swapcache pages to reclaim? */ > + if (total_swapcache_pages() > 0) { > + sc->swapcache_only = 1; > + return true; > + } > } else { > /* Is the memcg below its swap limit? */ > if (mem_cgroup_get_nr_swap_pages(memcg) > 0) > return true; > + /* Is there any swapcache pages in memcg to reclaim? */ > + if (mem_cgroup_get_nr_swapcache_pages(memcg) > 0) { > + sc->swapcache_only = 1; > + return true; > + } > } > > /* > @@ -2280,6 +2293,19 @@ static bool skip_cma(struct folio *folio, struct scan_control *sc) > } > #endif > > +static bool skip_isolate(struct folio *folio, struct scan_control *sc, > + enum lru_list lru) > +{ > + if (folio_zonenum(folio) > sc->reclaim_idx) > + return true; > + if (skip_cma(folio, sc)) > + return true; > + if (unlikely(sc->swapcache_only && !is_file_lru(lru) && > + !folio_test_swapcache(folio))) Just if (unlikely(sc->swapcache_only && !folio_test_swapcache(folio))) is enough. > + return true; > + return false; > +} > + > /* > * Isolating page from the lruvec to fill in @dst list by nr_to_scan times. > * > @@ -2326,8 +2352,7 @@ static unsigned long isolate_lru_folios(unsigned long nr_to_scan, > nr_pages = folio_nr_pages(folio); > total_scan += nr_pages; > > - if (folio_zonenum(folio) > sc->reclaim_idx || > - skip_cma(folio, sc)) { > + if (skip_isolate(folio, sc, lru)) { > nr_skipped[folio_zonenum(folio)] += nr_pages; > move_to = &folios_skipped; > goto move; -- Best Regards, Huang, Ying