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AJvYcCU5J3G/41q95CQ+e8UyIPxxTqYuq7hnwf3m/8Vo/L9nmaSJMhLn/SVdhJCUtMi68k5sYzSbM69klw==@kvack.org X-Gm-Message-State: AOJu0YxzJy9GowDALpj8rh2lpPJ6U4a71YugjmbZ/5TPF9AH3hud6yBM txO53BcyU2jw7rb97GI8C5J4jIDPCiyRYwYzCqeHmOHIdOvkUKMV6xmavcwYHnZD0ERn1DdV8Fj UGEstgYgfLV8vzkmaANyWLjASIY++Ow== X-Google-Smtp-Source: AGHT+IGQBsc+s67Y9dtP/Nqo/WXr4fyofXRCXEMfyRVr2g6j6uPJvtdnug0xWckMppaIyBMouiWcSXZ7dDxP9Zrrjx8= X-Received: by 2002:a05:6512:3e26:b0:535:681d:34b6 with SMTP id 2adb3069b0e04-539da5e2afdmr210814e87.10.1728633768604; Fri, 11 Oct 2024 01:02:48 -0700 (PDT) MIME-Version: 1.0 References: <20241009074953.608591-1-zhaoyang.huang@unisoc.com> In-Reply-To: From: Zhaoyang Huang Date: Fri, 11 Oct 2024 16:02:37 +0800 Message-ID: Subject: Re: [PATCH] mm: throttle and inc min_seq when both page types reach MIN_NR_GENS To: Yu Zhao Cc: "zhaoyang.huang" , Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org, steve.kang@unisoc.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 8BBF4180014 X-Stat-Signature: oxzq41r8eos4136ejehgc67wi79ybcxo X-Rspam-User: X-HE-Tag: 1728633768-59073 X-HE-Meta: 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 /gR5GizA Kmih6HjY8NWWeu2qAESz9Jy0qXF8ujNEh0tlNdwtMQLcKzv3X3XAT+UVeqHuDkC9t5ZaP9BOiBmeMJa7KX3GofgUJi4/gB2Tvk6aC/JWJfhqOp/1oZOAboejtoaS0SCyGutYttRFYNqlOZy1Kf4g/hZIizUocb7F09OMDBCodV9ieoTs7qtwKzmkQt9EIkR2sqq8QbcLDvcCK0BjdWvPvJLGWW80CZY0SltPdih+KRSutjvC5DvBfUgQq94gyO4pMMe1K4n8vx5apXMnTA6YrvFXcpaUGJNJl4c0uDV5dKjvBf0I0rD6HR3cUcatxq/d16fiOR5u8QY/OzkihrHHZj2kkAgk6PmF9MZ1Q2Sudz9E8CkMcEW/JvTcipB4h5G8MiCUNzxSBUVbQqHcXs8SRm2i2lR/Egh/7Q1ctmyxXjrXIrAidRSnHLoBdvp++nQZC6Mfp X-Bogosity: Ham, tests=bogofilter, spamicity=0.002358, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri, Oct 11, 2024 at 12:37=E2=80=AFAM Yu Zhao wrote: > > On Wed, Oct 9, 2024 at 1:50=E2=80=AFAM zhaoyang.huang wrote: > > > > From: Zhaoyang Huang > > > > The test case of [1] leads to system hang which caused by a local > > watchdog thread starved over 20s on a 5.5GB RAM ANDROID15(v6.6) > > system. This commit solve the issue by have the reclaimer be throttled > > and increase min_seq if both page types reach MIN_NR_GENS, which may > > introduce a livelock of switching type with holding lruvec->lru_lock. > > > > [1] > > launch below script 8 times simutanously which allocates 1GB virtual > > memory and access it from user space by each thread. > > $ costmem -c1024000 -b12800 -o0 & > > > > Signed-off-by: Zhaoyang Huang > > --- > > mm/vmscan.c | 16 ++++++++++++++-- > > 1 file changed, 14 insertions(+), 2 deletions(-) > > > > diff --git a/mm/vmscan.c b/mm/vmscan.c > > index cfa839284b92..83e450d0ce3c 100644 > > --- a/mm/vmscan.c > > +++ b/mm/vmscan.c > > @@ -4384,11 +4384,23 @@ static int scan_folios(struct lruvec *lruvec, s= truct scan_control *sc, > > int remaining =3D MAX_LRU_BATCH; > > struct lru_gen_folio *lrugen =3D &lruvec->lrugen; > > struct mem_cgroup *memcg =3D lruvec_memcg(lruvec); > > + struct pglist_data *pgdat =3D lruvec_pgdat(lruvec); > > > > VM_WARN_ON_ONCE(!list_empty(list)); > > > > - if (get_nr_gens(lruvec, type) =3D=3D MIN_NR_GENS) > > - return 0; > > + if (get_nr_gens(lruvec, type) =3D=3D MIN_NR_GENS) { > > + /* > > + * throttle for a while and then increase the min_seq s= ince > > + * both page types reach the limit. > > + */ > > Sorry but this isn't going to work because in try_to_inc_min_seq(), there= is > `while (min_seq[type] + MIN_NR_GENS <=3D lrugen->max_seq) {` > to prevent reclaimers from evicting hot memory -- they need to do aging f= irst. Thanks for heads up. What I thought was assuming there is a running reclaimer will do the aging and the throttled reclaimers increase the min_seq when scheduled back and move on. Or could we just drop the lock and throttle for a while to avoid a livelock on 'type =3D !type' with holding the lock? > > > > > + if (get_nr_gens(lruvec, !type) =3D=3D MIN_NR_GENS) { > > + spin_unlock_irq(&lruvec->lru_lock); > > + reclaim_throttle(pgdat, VMSCAN_THROTTLE_ISOLATE= D); > > + spin_lock_irq(&lruvec->lru_lock); > > + try_to_inc_min_seq(lruvec, get_swappiness(lruve= c, sc)); > > + } else > > + return 0; > > + } > > > > gen =3D lru_gen_from_seq(lrugen->min_seq[type]); > > > > -- > > 2.25.1 > >