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[141.239.149.160]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-1fb57299335sm10136725ad.128.2024.07.05.10.13.31 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 05 Jul 2024 10:13:31 -0700 (PDT) Sender: Tejun Heo Date: Fri, 5 Jul 2024 07:13:30 -1000 From: Tejun Heo To: "boy.wu" Cc: Josef Bacik , Jens Axboe , Matthias Brugger , AngeloGioacchino Del Regno , Boris Burkov , cgroups@vger.kernel.org, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mediatek@lists.infradead.org, iverlin.wang@mediatek.com Subject: Re: [PATCH] blk-cgroup: add spin_lock for u64_stats_update Message-ID: References: <20240705075544.11315-1-boy.wu@mediatek.com> Precedence: bulk X-Mailing-List: cgroups@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240705075544.11315-1-boy.wu@mediatek.com> Hello, On Fri, Jul 05, 2024 at 03:55:44PM +0800, boy.wu wrote: > From: Boy Wu > > In 32bit SMP systems, if the system is stressed on the sys node > by processes, it may cause blkcg_fill_root_iostats to have a concurrent What is sys node? > problem on the seqlock in u64_stats_update, which will cause a deadlock > on u64_stats_fetch_begin in blkcg_print_one_stat. I'm not following the scenario. Can you please detail the scenario where this leads to deadlocks? Thanks. -- tejun