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 2AA74285404; Wed, 4 Feb 2026 15:01:22 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770217282; cv=none; b=Ci7zxcL4HP+USmWCcdr7hVXQHR2pJBynNdHVYxb38ZW9H30sKT0FMiYnJi0JRO9CFbDtSdpLOZVBMP6MR6ceey9VwzVuso//osTDjVfFOH8ahJ9988pWcLP1HCENcl3FoNwISg2rzKmx6uKJJRPR7JmtsmAokQDEBe8ckHlAlmQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770217282; c=relaxed/simple; bh=NaW6EObdiHgyAEAV2NKMLdAdVFgEiFeVDwoH2+iXNco=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=tHQeVGSWTZVvIrCCld6YzHGqIQ3lm5okVvi1IXfkfkuYjYindZDjHckns+yVy1g0nr5/Q/HZ8yjGEMTt11tC/TXSh8UtL9KLYvUOiwDVXeKG1UZusOonsYlZchFjKEkzo9XIE4/+hj4Pae3nLg5Lk2F3N+8dJRItlVpCkYlauBk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=VshDzm4F; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="VshDzm4F" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8F974C4CEF7; Wed, 4 Feb 2026 15:01:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1770217282; bh=NaW6EObdiHgyAEAV2NKMLdAdVFgEiFeVDwoH2+iXNco=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=VshDzm4Fvq9nbeJSAzRMfBJ4/FVwgZsAd9Ew+y6N9rxp15AMj/mTBnQpY2C+H8ApJ 8wgKuBn4EH4kFOQ5nWt9Kf3JfwdLCf+zsAka5OrqReiu2Cs33C6/3yBQGVzXlDaAJZ nbMSisnBGoXvSPmq9spcodYIWARkCyw8Fd7B4a9M= 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 , Alva Lan Subject: [PATCH 5.15 178/206] blk-cgroup: Reinit blkg_iostat_set after clearing in blkcg_reset_stats() Date: Wed, 4 Feb 2026 15:40:09 +0100 Message-ID: <20260204143904.625973281@linuxfoundation.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260204143858.193781818@linuxfoundation.org> References: <20260204143858.193781818@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Waiman Long [ Upstream commit 3d2af77e31ade05ff7ccc3658c3635ec1bea0979 ] 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 [ Remove this line: bis -> blkg = blkg for blkg was introduced by commit 3b8cc6298724 ("blk-cgroup: Optimize blkcg_rstat_flush()") since v6.2. ] Signed-off-by: Alva Lan Signed-off-by: Greg Kroah-Hartman --- block/blk-cgroup.c | 4 ++++ 1 file changed, 4 insertions(+) --- a/block/blk-cgroup.c +++ b/block/blk-cgroup.c @@ -491,8 +491,12 @@ 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); } 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];