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Wed, 26 Nov 2025 17:39:16 -0800 (PST) Received: from localhost.localdomain ([101.71.133.196]) by smtp.googlemail.com with ESMTPSA id d9443c01a7336-29b5b107cc2sm212427815ad.16.2025.11.26.17.39.14 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Wed, 26 Nov 2025 17:39:16 -0800 (PST) From: Fengnan Chang To: axboe@kernel.dk, linux-block@vger.kernel.org, ming.lei@redhat.com, hare@suse.de, hch@lst.de, yukuai3@huawei.com Cc: Fengnan Chang Subject: [PATCH v2 0/2] blk-mq: use array manage hctx map instead of xarray Date: Thu, 27 Nov 2025 09:39:06 +0800 Message-Id: <20251127013908.66118-1-fengnanchang@gmail.com> X-Mailer: git-send-email 2.39.5 (Apple Git-154) Precedence: bulk X-Mailing-List: linux-block@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Fengnan Chang After commit 4e5cc99e1e48 ("blk-mq: manage hctx map via xarray"), we use an xarray instead of array to store hctx, but in poll mode, each time in blk_mq_poll, we need use xa_load to find corresponding hctx, this introduce some costs. In my test, xa_load may cost 3.8% cpu. After revert previous change, eliminates the overhead of xa_load and can result in a 3% performance improvement. potentital use-after-free on q->queue_hw_ctx can be fixed by use rcu to avoid, same as Yu Kuai did in [1]. [1] https://lore.kernel.org/all/20220225072053.2472431-1-yukuai3@huawei.com/ Fengnan Chang (2): blk-mq: use array manage hctx map instead of xarray blk-mq: fix potential uaf for 'queue_hw_ctx' block/blk-mq-tag.c | 2 +- block/blk-mq.c | 63 ++++++++++++++++++++++++++++-------------- block/blk-mq.h | 13 ++++++++- include/linux/blk-mq.h | 3 +- include/linux/blkdev.h | 2 +- 5 files changed, 58 insertions(+), 25 deletions(-) base-commit: 4941a17751c99e17422be743c02c923ad706f888 -- 2.39.5 (Apple Git-154)