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 94AAE2BE7C0; Wed, 4 Feb 2026 15:17:52 +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=1770218272; cv=none; b=pCLQdxbwA4nxn0QxQbK04rDqzl6eG+4taNvAXJIfbAkxGsLXN8CEIhp055yP6yrTnhoCn0ejeSP0Tn7dWyjP50yZiwURenxg5kuV3qS0fV8Gemrv/Q6xRWZ8AE52EiuhMRzC/7AOVk4BLgzuAHj+JaPGj2kU2CGPIae3fYU4938= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770218272; c=relaxed/simple; bh=5iFf3jn30wgNrKmPDLbLQmbnRIR3fPATdn/SCYHQAmI=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Z5oFx4yjiOV9CiUl+7eiWENEJ6TVHg27YBpOcO6IFDxolMcYNbQwfB3vC/3EM68dWew7zWY8qZzczwVAtvW3A645q9Ta+GoSwEgEMwg/LIM8Bnb7K1modKCA97+YxxREmCdAO1oeTZkoJRvqQmqM0EaBMHB2hQmoppRyUkRTgcw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=BbRcX3Nt; 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="BbRcX3Nt" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 029DEC4CEF7; Wed, 4 Feb 2026 15:17:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1770218272; bh=5iFf3jn30wgNrKmPDLbLQmbnRIR3fPATdn/SCYHQAmI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=BbRcX3NtRZ5ZeOaowJHXzsq/lfsfYPeDlNW73EHmyzQ934Mjr6MyXd/TVnnepewSU cnoMBrYqYpoCtVh11+2Opxpw8MEQII1/2MwZeU+XpX4M3fWl9s8Q6mVLKBHL3Rmbf8 hvwvZp7jfw6f4rkji4cTIVRn2G4g5O6gr6jsEiTk= 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 6.1 261/280] blk-cgroup: Reinit blkg_iostat_set after clearing in blkcg_reset_stats() Date: Wed, 4 Feb 2026 15:40:35 +0100 Message-ID: <20260204143919.090825055@linuxfoundation.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260204143909.614719725@linuxfoundation.org> References: <20260204143909.614719725@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 6.1-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 @@ -531,8 +531,12 @@ 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];