From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from dggsgout11.his.huawei.com (dggsgout11.his.huawei.com [45.249.212.51]) (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 D6BE233FE12; Thu, 15 Jan 2026 09:22:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.249.212.51 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768468944; cv=none; b=tL8qsqtCj+I53zLS8rpOLPG3xeBAXFkfovROhJiQ5tN9isXZVGmij2MrWVSFbUsYYP60YWXMs80QUjC+asEAa+TVnqbrQ6TPfZRK2fcYc7QmqZ9llwVkJlOaask/vRbgQVWcLWk5J340MvyAN7s9OK2C+kDtfdkM09BFxsGsCnE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768468944; c=relaxed/simple; bh=bYa1IO7G8wpbljLg/01e+Wci3w/MMDpVcOldCC7TMxM=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=aTxzTrReXEAaMn7lIs7v0dBNdzBgWE7HuJcfnsxA+d/AndkSWVaL/HbyET5UZCOG63Pd+R86MZ+WdG+8Q1hXCAiyRe1m85Ea7MOxtfpCo2lIyZ43vKbVS5XTeF7OuChvSBmNuNfSr250tNbA2jAoMAjJpdGM6TnKvNmmoxRti+A= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=huaweicloud.com; spf=pass smtp.mailfrom=huaweicloud.com; arc=none smtp.client-ip=45.249.212.51 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=huaweicloud.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huaweicloud.com Received: from mail.maildlp.com (unknown [172.19.163.177]) by dggsgout11.his.huawei.com (SkyGuard) with ESMTPS id 4dsHYk1tgszYQv3l; Thu, 15 Jan 2026 17:22:02 +0800 (CST) Received: from mail02.huawei.com (unknown [10.116.40.128]) by mail.maildlp.com (Postfix) with ESMTP id 685FB40595; Thu, 15 Jan 2026 17:22:17 +0800 (CST) Received: from [10.174.178.72] (unknown [10.174.178.72]) by APP4 (Coremail) with SMTP id gCh0CgBHqPjHsWhpF4+EDw--.7204S3; Thu, 15 Jan 2026 17:22:17 +0800 (CST) Message-ID: <78362ecd-3f80-471f-8e08-e487f0792c11@huaweicloud.com> Date: Thu, 15 Jan 2026 17:22:13 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 2/3] blk-cgroup: skip dying blkg in blkcg_activate_policy() To: yukuai@fnnas.com Cc: cgroups@vger.kernel.org, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, mkoutny@suse.com, yi.zhang@huawei.com, yangerkun@huawei.com, houtao1@huawei.com, tj@kernel.org, josef@toxicpanda.com, axboe@kernel.dk, hch@infradead.org, Zheng Qixing References: <20260113061035.1902522-1-zhengqixing@huaweicloud.com> <20260113061035.1902522-3-zhengqixing@huaweicloud.com> <50d63ff3-97ef-499f-961d-cf6766a8028b@fnnas.com> From: Zheng Qixing In-Reply-To: <50d63ff3-97ef-499f-961d-cf6766a8028b@fnnas.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-CM-TRANSID:gCh0CgBHqPjHsWhpF4+EDw--.7204S3 X-Coremail-Antispam: 1UD129KBjvdXoWrtFyDuF45Cw4xGrW7CrWUCFg_yoWfKrcE9a 48A3sFvFWkZa9Ykrn0vF15XrZIk3yDXry29r9YqF97ta45JF4fAr43Cw17WF43Aa47Cry5 urWqg3Z7Gr4SvjkaLaAFLSUrUUUUjb8apTn2vfkv8UJUUUU8Yxn0WfASr-VFAUDa7-sFnT 9fnUUIcSsGvfJTRUUUbxxYFVCjjxCrM7AC8VAFwI0_Gr0_Xr1l1xkIjI8I6I8E6xAIw20E Y4v20xvaj40_Wr0E3s1l1IIY67AEw4v_Jr0_Jr4l8cAvFVAK0II2c7xJM28CjxkF64kEwV A0rcxSw2x7M28EF7xvwVC0I7IYx2IY67AKxVW7JVWDJwA2z4x0Y4vE2Ix0cI8IcVCY1x02 67AKxVW8Jr0_Cr1UM28EF7xvwVC2z280aVAFwI0_GcCE3s1l84ACjcxK6I8E87Iv6xkF7I 0E14v26rxl6s0DM2AIxVAIcxkEcVAq07x20xvEncxIr21l5I8CrVACY4xI64kE6c02F40E x7xfMcIj6xIIjxv20xvE14v26r1j6r18McIj6I8E87Iv67AKxVW8JVWxJwAm72CE4IkC6x 0Yz7v_Jr0_Gr1lF7xvr2IY64vIr41lFIxGxcIEc7CjxVA2Y2ka0xkIwI1lc7CjxVAaw2AF wI0_Jw0_GFyl42xK82IYc2Ij64vIr41l4I8I3I0E4IkC6x0Yz7v_Jr0_Gr1lx2IqxVAqx4 xG67AKxVWUJVWUGwC20s026x8GjcxK67AKxVWUGVWUWwC2zVAF1VAY17CE14v26r1q6r43 MIIYrxkI7VAKI48JMIIF0xvE2Ix0cI8IcVAFwI0_Jr0_JF4lIxAIcVC0I7IYx2IY6xkF7I 0E14v26r4j6F4UMIIF0xvE42xK8VAvwI8IcIk0rVWUJVWUCwCI42IY6I8E87Iv67AKxVWU JVW8JwCI42IY6I8E87Iv6xkF7I0E14v26r4j6r4UJbIYCTnIWIevJa73UjIFyTuYvjxUzt xhDUUUU X-CM-SenderInfo: x2kh0wptl0x03j6k3tpzhluzxrxghudrp/ >> diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c >> index 600f8c5843ea..5dbc107eec53 100644 >> --- a/block/blk-cgroup.c >> +++ b/block/blk-cgroup.c >> @@ -1622,9 +1622,10 @@ int blkcg_activate_policy(struct gendisk *disk, const struct blkcg_policy *pol) >> * GFP_NOWAIT failed. Free the existing one and >> * prealloc for @blkg w/ GFP_KERNEL. >> */ >> + if (!blkg_tryget(blkg)) >> + continue; > So, why this check is still before the pd_alloc_fn()? You mean 'after'? > See blkg_destroy(), can you replace this by the same checking: > > list_for_each_entry_reverse() > if (hlist_unhashed(&blkg->blkcg_node)) > continue; > if (blkg->pd[pol->plid]) > continue; This change makes sense. This issue can be resolved by either doing tryget(blkg) before pd_alloc_fn() or by accessing blkg->blkcg_node. To keep the behavior consistent with blkg_destroy() and blkg_destroy_all(), I will revise this in v3. Thank, Qixing