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b=rN6nfYWXa6A8OwG98JwxNdimUmeTuLBDije5l3qJbbm0bOKzBefkWcxrg3l32N7kK 6fjf/6VCdgQaNhdU06FfL7sIVFlcjwK4uc9JDUNfGMNCp3yfRhUxQ8C0Kkd5aD2J2c o98Jgw4ooUtiM/TGWMrPsR73bMFIvpQ9YidFhECA= Date: Wed, 25 Sep 2024 13:51:11 -0700 From: Andrew Morton To: Zhiguo Jiang Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, opensource.kernel@vivo.com Subject: Re: [PATCH] mm: fix shrink nr.unqueued_dirty counter issue Message-Id: <20240925135111.4a82c0a126114d3f8bcc7abd@linux-foundation.org> In-Reply-To: <20240112012353.1387-1-justinjiang@vivo.com> References: <20240112012353.1387-1-justinjiang@vivo.com> X-Mailer: Sylpheed 3.7.0 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: DAD06100014 X-Stat-Signature: t5b6ddr3zikms4is7xwo331cb4qjsxmo X-Rspam-User: X-HE-Tag: 1727297472-218036 X-HE-Meta: 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 mNZennGK IhEBl2ZWXSfkly7MczlFpzzAwXKtdzgG68fnfP5FARqRlsTO5v45bQf1vxrWEmJbDRGPVIptwAGA0xs8v0o0UMugHU40uIMDti3E5g1J//LDwQza0opkBwcFNNHM7kn4o80Un14JSrPNZzgFfsP+pMvR0M7Xzboy7pPuqtXTHAHSbASFkjenniQw/QzNbTdDJIMnSlKjsPGZd/vsT2RcFZDJRiajI39KISoXmpz2CyasyGPvAqzgwbEzT+xgQEMtnKvfGl7Ii+9YqjlGFDTPxJpHPlm6H3bnbg90hNMK4pLpUeFZ8KHFHiMoJQ50PWHjW/qRf2358ZFkuUG6dCcWEsY1ytA== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000069, 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, 12 Jan 2024 09:23:52 +0800 Zhiguo Jiang wrote: > It is needed to ensure sc->nr.unqueued_dirty > 0, which can avoid to > set PGDAT_DIRTY flag when sc->nr.unqueued_dirty and sc->nr.file_taken > are both zero at the same time. > > ... > > --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -5957,7 +5957,8 @@ static void shrink_node(pg_data_t *pgdat, struct scan_control *sc) > set_bit(PGDAT_WRITEBACK, &pgdat->flags); > > /* Allow kswapd to start writing pages during reclaim.*/ > - if (sc->nr.unqueued_dirty == sc->nr.file_taken) > + if (sc->nr.unqueued_dirty && > + sc->nr.unqueued_dirty == sc->nr.file_taken) > set_bit(PGDAT_DIRTY, &pgdat->flags); > Seems sensible. Was this discovered by code inspection, or is there some observable runtime effect? If the latter, can you please describe that effect?