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([2a0c:5a80:1306:2f00:cfcf:62cf:6f38:dd92]) by smtp.gmail.com with ESMTPSA id n5-20020a170906378500b006efb4ab6f59sm3328411ejc.86.2022.04.20.07.35.05 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 20 Apr 2022 07:35:05 -0700 (PDT) Message-ID: Subject: Re: [PATCH 5/6] mm/page_alloc: Protect PCP lists with a spinlock From: Nicolas Saenz Julienne To: Hillf Danton , Mel Gorman Cc: Marcelo Tosatti , Vlastimil Babka , Michal Hocko , LKML , Linux-MM Date: Wed, 20 Apr 2022 16:35:04 +0200 In-Reply-To: <20220420140214.2330-1-hdanton@sina.com> References: <20220420095906.27349-1-mgorman@techsingularity.net> <20220420140214.2330-1-hdanton@sina.com> User-Agent: Evolution 3.42.4 (3.42.4-2.fc35) MIME-Version: 1.0 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: B7043A0021 X-Stat-Signature: xp1forap1nue69jhqs5a88xe1cp6wxwp Authentication-Results: imf25.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b="EOs+8/Ap"; dmarc=pass (policy=none) header.from=redhat.com; spf=none (imf25.hostedemail.com: domain of nsaenzju@redhat.com has no SPF policy when checking 170.10.129.124) smtp.mailfrom=nsaenzju@redhat.com X-HE-Tag: 1650465307-960445 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: Hi Hillf, On Wed, 2022-04-20 at 22:02 +0800, Hillf Danton wrote: > On Wed, 20 Apr 2022 10:59:05 +0100 Mel Gorman wrote: > > void drain_zone_pages(struct zone *zone, struct per_cpu_pages *pcp) > > { > > - unsigned long flags; > > int to_drain, batch; > > > > - local_lock_irqsave(&pagesets.lock, flags); > > batch = READ_ONCE(pcp->batch); > > to_drain = min(pcp->count, batch); > > - if (to_drain > 0) > > + if (to_drain > 0) { > > + unsigned long flags; > > + > > + /* free_pcppages_bulk expects IRQs disabled for zone->lock */ > > + local_irq_save(flags); > > + > > + spin_lock(&pcp->lock); > > Nit, spin_lock_irqsave() instead. See cover letter's: "This series is a partial series. Follow-on work would allow the local_irq_save to be converted to a local_irq to avoid IRQs being disabled/enabled in most cases. However, there are enough corner cases that it deserves a series on its own separated by one kernel release and the priority right now is to avoid interference of high priority tasks." Regards, -- Nicolás Sáenz