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[109.252.193.60]) by smtp.googlemail.com with ESMTPSA id d13sm218870lfi.247.2021.03.24.05.37.03 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 24 Mar 2021 05:37:03 -0700 (PDT) Subject: Re: [PATCH v6] mm: cma: support sysfs To: Minchan Kim , John Hubbard Cc: Andrew Morton , linux-mm , LKML , gregkh@linuxfoundation.org, surenb@google.com, joaodias@google.com, willy@infradead.org References: <20210324010547.4134370-1-minchan@kernel.org> From: Dmitry Osipenko Message-ID: <5b1a9f6c-ea7b-6e90-1c77-a49a10896f08@gmail.com> Date: Wed, 24 Mar 2021 15:37:02 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.8.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 24.03.2021 08:44, Minchan Kim пишет: > On Tue, Mar 23, 2021 at 09:47:27PM -0700, John Hubbard wrote: >> On 3/23/21 8:27 PM, Minchan Kim wrote: >> ... >>>>> +static int __init cma_sysfs_init(void) >>>>> +{ >>>>> + unsigned int i; >>>>> + >>>>> + cma_kobj_root = kobject_create_and_add("cma", mm_kobj); >>>>> + if (!cma_kobj_root) >>>>> + return -ENOMEM; >>>>> + >>>>> + for (i = 0; i < cma_area_count; i++) { >>>>> + int err; >>>>> + struct cma *cma; >>>>> + struct cma_kobject *cma_kobj; >>>>> + >>>>> + cma_kobj = kzalloc(sizeof(*cma_kobj), GFP_KERNEL); >>>>> + if (!cma_kobj) { >>>>> + kobject_put(cma_kobj_root); >>>>> + return -ENOMEM; >>>> >>>> This leaks little cma_kobj's all over the floor. :) >>> >>> I thought kobject_put(cma_kobj_root) should deal with it. No? >>> >> If this fails when i > 0, there will be cma_kobj instances that >> were stashed in the cma_areas[] array. But this code only deletes >> the most recently allocated cma_kobj, not anything allocated on >> previous iterations of the loop. > > Oh, I misunderstood that destroying of root kobject will release > children recursively. Seems not true. Go back to old version. > > > index 16c81c9cb9b7..418951a3f138 100644 > --- a/mm/cma_sysfs.c > +++ b/mm/cma_sysfs.c > @@ -80,20 +80,19 @@ static struct kobj_type cma_ktype = { > static int __init cma_sysfs_init(void) > { > unsigned int i; > + int err; > + struct cma *cma; > + struct cma_kobject *cma_kobj; > > cma_kobj_root = kobject_create_and_add("cma", mm_kobj); > if (!cma_kobj_root) > return -ENOMEM; > > for (i = 0; i < cma_area_count; i++) { > - int err; > - struct cma *cma; > - struct cma_kobject *cma_kobj; > - > cma_kobj = kzalloc(sizeof(*cma_kobj), GFP_KERNEL); > if (!cma_kobj) { > - kobject_put(cma_kobj_root); > - return -ENOMEM; > + err = -ENOMEM; > + goto out; > } > > cma = &cma_areas[i]; > @@ -103,11 +102,21 @@ static int __init cma_sysfs_init(void) > cma_kobj_root, "%s", cma->name); > if (err) { > kobject_put(&cma_kobj->kobj); > - kobject_put(cma_kobj_root); > - return err; > + goto out; > } > } > > return 0; > +out: > + while (--i >= 0) { > + cma = &cma_areas[i]; > + > + kobject_put(&cma->kobj->kobj); > + kfree(cma->kobj); > + cma->kobj = NULL; > + } > + kobject_put(cma_kobj_root); > + > + return err; > } > subsys_initcall(cma_sysfs_init); Since we don't care about the order in which kobjects are put, I'd write it in this way, which I think looks cleaner: static void cma_sysfs_cleanup(struct kobject *cma_kobj_root) { struct cma *cma = cma_areas; unsigned int i; for (i = 0; i < cma_area_count; i++, cma++) { if (!cma->kobj) break; kobject_put(&cma->kobj->kobj); } kobject_put(cma_kobj_root); } static int __init cma_sysfs_init(void) { struct kobject *cma_kobj_root; unsigned int i; cma_kobj_root = kobject_create_and_add("cma", mm_kobj); if (!cma_kobj_root) return -ENOMEM; for (i = 0; i < cma_area_count; i++) { struct cma_kobject *cma_kobj; struct cma *cma; int err; cma_kobj = kzalloc(sizeof(*cma_kobj), GFP_KERNEL); if (!cma_kobj) { cma_sysfs_cleanup(cma_kobj_root); return -ENOMEM; } cma = &cma_areas[i]; cma->kobj = cma_kobj; cma_kobj->cma = cma; err = kobject_init_and_add(&cma_kobj->kobj, &cma_ktype, cma_kobj_root, "%s", cma->name); if (err) { cma_sysfs_cleanup(cma_kobj_root); return err; } } return 0; } subsys_initcall(cma_sysfs_init);