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X-IronPort-AV: E=McAfee;i="6600,9927,10815"; a="354572887" X-IronPort-AV: E=Sophos;i="6.02,207,1688454000"; d="scan'208";a="354572887" Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by fmsmga106.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 28 Aug 2023 01:38:13 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.01,202,1684825200"; d="scan'208";a="881861962" Received: from yhuang6-desk2.sh.intel.com (HELO yhuang6-desk2.ccr.corp.intel.com) ([10.238.208.55]) by fmsmga001-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 28 Aug 2023 01:38:11 -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> <87il9053zo.fsf@yhuang6-desk2.ccr.corp.intel.com> <2992c888-b8c7-d93b-d132-ea90e2c516e3@huawei.com> Date: Mon, 28 Aug 2023 16:35:55 +0800 In-Reply-To: <2992c888-b8c7-d93b-d132-ea90e2c516e3@huawei.com> (Liu Shixin's message of "Mon, 28 Aug 2023 15:11:19 +0800") Message-ID: <87a5ub5ztg.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-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 2CBB3180011 X-Stat-Signature: frzx7ximomsef9rzcne97ssd9p8btiz6 X-HE-Tag: 1693211900-650880 X-HE-Meta: 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 I3jUIJSO VX8J7Xy6lOV57NKKiKv+yGyMhHSwcIrR4wb02OXLHd4LpNRLKZquPDLyLYKYuk+Og07bv0PSPDY8CQAXigpx2I/QOODr7v9FUI0oynRKEPyJbDnTSP2YvGTaTs/u2uLWZx9IgM0RoANL8c8FzR1FEsKA2jTXkCYm9jePwnVH4h1sg2FdhNNEn8qGq4yK8KEBRgLVjeK9KkSYpH1v5pYaM5Lk7crPbrWycoqAj 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: > On 2023/8/28 9:51, Huang, Ying wrote: >> 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. > OK, I will add the infomation. >> >>> 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. > That would results the file pages to be skipped too, but what expected is to skip non-swapcache > pages in anon lru list. So I think the condition !is_file_lru(lru) is required. Ah, you are right. -- Best Regards, Huang, Ying >> >>> + 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;