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Mon, 3 Aug 2026 09:09:15 +0000 (GMT) Message-ID: <523e4487-4ac8-434d-bebe-03ae8212b577@linux.ibm.com> Date: Mon, 3 Aug 2026 14:39:14 +0530 Precedence: bulk X-Mailing-List: cgroups@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 0/4] blk-cgroup: fix blkg list and policy data races To: yukuai@fygo.io, tj@kernel.org, axboe@kernel.dk Cc: cgroups@vger.kernel.org, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, zhengqixing@huawei.com, hch@lst.de, yizhou.tang@shopee.com References: <20260802112525.3933753-1-yukuai@kernel.org> <431ed2f9-9fde-4ff7-9db7-51a56bec17c0@linux.ibm.com> <055d481c-dbfe-4749-82f0-49e330724d86@fygo.io> Content-Language: en-US From: Nilay Shroff In-Reply-To: <055d481c-dbfe-4749-82f0-49e330724d86@fygo.io> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: XCjIQ9IOPkvhEFIOo8wsvYedr-Y8wWny X-Proofpoint-Spam-Info: AW1haW4tMjYwODAzMDA3NyBTYWx0ZWRfX1vDX06BnoTaX 3/Lc+lYcub1ROPT9V54i4XMEoKQ0Fs/3A8uuJZf555lTG9oWIo3yI2fmmugpAnpb5e8FDXPcdTH 3TyGdWMtinSgRwVJdCCoSsoIYaQzdWA= X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwODAzMDA3NyBTYWx0ZWRfX+0KbfQo+B3za DG7EKEw6BJLisckpp0V9DAIpd8xyyuCLXzKAoVwTtz6ntgw5SpEn8XxfmOKNup06eqaNJSVr0mD IDweyYkRau97vtOM+amwg8xFkJ+1rJfN7UxL3Dx4MHcjXv2BIsDQ32i4bZvi/SBrkUJzvWyyA41 ovfMJQue2ZJcLnt3tzm+ylLMaPm0EfTdI2u8zBtJeTTeVYZCs9/EHlR+8wfZM+Xw74XF9QxgPOd FUUWIC8SdYLXYjlsRFEKbv5DQ2WG+zDotQk/MUWkvvdCqPN0CZjHxDwlcgfLDemXljHKrGkcIt2 LgCx3zDsvOHwBqIa42YPc7PrJkiVG+HJYzzuW/oLLA7oM/p6jGZQf8thfodKGWezYL+qtaHUHBb mmXiJRhzmPkwugAfdZwtC8zWeew8FXsSOeIRAO5FF5eHwt+cyowWa0I3cS/efNl9pUWxeNjNHN6 +TZ0bMxlLrT8uinDDZg== X-Proofpoint-GUID: XCjIQ9IOPkvhEFIOo8wsvYedr-Y8wWny X-Authority-Analysis: v=2.4 cv=KfzidwYD c=1 sm=1 tr=0 ts=6a705ac1 cx=c_pps a=GFwsV6G8L6GxiO2Y/PsHdQ==:117 a=GFwsV6G8L6GxiO2Y/PsHdQ==:17 a=IkcTkHD0fZMA:10 a=Sv0fKeRqtYgA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=RzCfie-kr_QcCd8fBx8p:22 a=VwQbUJbxAAAA:8 a=VnNF1IyMAAAA:8 a=9tl1nHjhYCbjcLoMjjMA:9 a=3ZKOabzyN94A:10 a=QEXdDO2ut3YA:10 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-08-02_06,2026-07-30_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 lowpriorityscore=0 bulkscore=0 impostorscore=0 suspectscore=0 malwarescore=0 adultscore=0 clxscore=1015 priorityscore=1501 phishscore=0 spamscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2608030077 On 8/3/26 1:50 PM, yu kuai wrote: > Hi, > > 在 2026/8/3 14:51, Nilay Shroff 写道: >> On 8/2/26 4:55 PM, Yu Kuai wrote: >>> From: Yu Kuai >>> >>> This set fix some problems that are reported long time ago with >>> minimal changes, >>> the blkcg_mutex refactor I'm working on can fix these problems as >>> well, but it's >>> complicated and may not land in this merge window. So I think this >>> set should land >>> in this merge window first. >>> >>> Patch 1 protects blkg_destroy_all()'s q->blkg_list walk with >>> blkcg_mutex. >>> >>> Patches 2-3 fix races between blkcg_activate_policy() and concurrent >>> blkg destruction. >>> >>> Patch 4 factors the policy data teardown loop into a helper after the >>> race fixes. >>> >> >> This series looks good to me, however as I recall, we discussed about >> protecting blkg_create() as well using ->blkcg_mutex. I remember the >> blkg_create() is not protected with ->blkcg_mutex under each call path, >> so would you to also cover that change in this patchset? > > I can't do this for now without a big refactor, because it's possible that > blkg_create() can be called from bio_set_dev(), and bio_set_dev() can be > called from many atomic contexts, examples are patch 1,2,3,5,8,9,10 from the > following RFC v1 set: > > [RFC PATCH v1 00/17] blk-cgroup: protect blkgs with blkcg_mutex - Yu Kuai > Okay understood. With that, for this entire patchset: Reviewed-by: Nilay Shroff