From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 11D038F57 for ; Sun, 16 Jul 2023 20:58:01 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8691CC433C8; Sun, 16 Jul 2023 20:58:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1689541080; bh=y/EoI4KziwaiscMxShkNHscVQPz8OttEbzjiuxCsC2U=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=m1go+FPRFx6qxeHglmIgRQ0KABvJPwL2p34Fz2nZBR5YQZus2o6uQb/vA5KvrstD9 usRFWMC1Ne7IAyiY2vO0DC+8Qum9gIFKHspnEru/ojrmvhNyJDtyo8USorBjsr7yGC 65BsHN4zm8E7dBSWZKlTsMX3VwxK62JzghMDDTkk= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Waiman Long , Ming Lei , Tejun Heo , Jens Axboe Subject: [PATCH 6.1 582/591] blk-cgroup: Reinit blkg_iostat_set after clearing in blkcg_reset_stats() Date: Sun, 16 Jul 2023 21:52:01 +0200 Message-ID: <20230716194938.912863484@linuxfoundation.org> X-Mailer: git-send-email 2.41.0 In-Reply-To: <20230716194923.861634455@linuxfoundation.org> References: <20230716194923.861634455@linuxfoundation.org> User-Agent: quilt/0.67 Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Waiman Long commit 3d2af77e31ade05ff7ccc3658c3635ec1bea0979 upstream. When blkg_alloc() is called to allocate a blkcg_gq structure with the associated blkg_iostat_set's, there are 2 fields within blkg_iostat_set that requires proper initialization - blkg & sync. The former field was introduced by commit 3b8cc6298724 ("blk-cgroup: Optimize blkcg_rstat_flush()") while the later one was introduced by commit f73316482977 ("blk-cgroup: reimplement basic IO stats using cgroup rstat"). Unfortunately those fields in the blkg_iostat_set's are not properly re-initialized when they are cleared in v1's blkcg_reset_stats(). This can lead to a kernel panic due to NULL pointer access of the blkg pointer. The missing initialization of sync is less problematic and can be a problem in a debug kernel due to missing lockdep initialization. Fix these problems by re-initializing them after memory clearing. Fixes: 3b8cc6298724 ("blk-cgroup: Optimize blkcg_rstat_flush()") Fixes: f73316482977 ("blk-cgroup: reimplement basic IO stats using cgroup rstat") Signed-off-by: Waiman Long Reviewed-by: Ming Lei Acked-by: Tejun Heo Link: https://lore.kernel.org/r/20230606180724.2455066-1-longman@redhat.com Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman --- block/blk-cgroup.c | 5 +++++ 1 file changed, 5 insertions(+) --- a/block/blk-cgroup.c +++ b/block/blk-cgroup.c @@ -544,8 +544,13 @@ static int blkcg_reset_stats(struct cgro struct blkg_iostat_set *bis = per_cpu_ptr(blkg->iostat_cpu, cpu); memset(bis, 0, sizeof(*bis)); + + /* Re-initialize the cleared blkg_iostat_set */ + u64_stats_init(&bis->sync); + bis->blkg = blkg; } memset(&blkg->iostat, 0, sizeof(blkg->iostat)); + u64_stats_init(&blkg->iostat.sync); for (i = 0; i < BLKCG_MAX_POLS; i++) { struct blkcg_policy *pol = blkcg_policy[i];