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[109.252.193.60]) by smtp.googlemail.com with ESMTPSA id z64sm318457lfa.92.2021.03.24.13.02.47 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 24 Mar 2021 13:02:48 -0700 (PDT) Subject: Re: [PATCH] mm: cma: fix corruption cma_sysfs_alloc_pages_count To: Minchan Kim Cc: Andrew Morton , linux-mm , LKML , gregkh@linuxfoundation.org, surenb@google.com, joaodias@google.com, jhubbard@nvidia.com, willy@infradead.org References: <20210324192044.1505747-1-minchan@kernel.org> <18ee5c3e-fba2-0d8d-bd93-5fb8d0dd7a01@gmail.com> <89ba4c7a-42d2-5412-2367-cc1cffc1117b@gmail.com> From: Dmitry Osipenko Message-ID: <900f5707-3352-e3d1-69e8-c1f8580c0fc4@gmail.com> Date: Wed, 24 Mar 2021 23:02:47 +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 X-Stat-Signature: h1pmmstboskx3kysj7i5p96sz8531rcu X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: BA3D84080F4F Received-SPF: none (gmail.com>: No applicable sender policy available) receiver=imf02; identity=mailfrom; envelope-from=""; helo=mail-lj1-f171.google.com; client-ip=209.85.208.171 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1616616167-619718 Content-Transfer-Encoding: quoted-printable X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 24.03.2021 22:57, Minchan Kim =D0=BF=D0=B8=D1=88=D0=B5=D1=82: > On Wed, Mar 24, 2021 at 10:49:58PM +0300, Dmitry Osipenko wrote: >> 24.03.2021 22:43, Dmitry Osipenko =D0=BF=D0=B8=D1=88=D0=B5=D1=82: >>> 24.03.2021 22:20, Minchan Kim =D0=BF=D0=B8=D1=88=D0=B5=D1=82: >>>> static int __init cma_sysfs_init(void) >>>> { >>>> - int i =3D 0; >>>> + struct kobject *cma_kobj_root; >>>> + struct cma_kobject *cma_kobj; >>>> struct cma *cma; >>>> + unsigned int i; >>> >>>> while (--i >=3D 0) { >>> >>> Do you realize that this doesn't work anymore? >>> >>>> cma =3D &cma_areas[i]; >>>> - kobject_put(&cma->stat->kobj); >>>> - } >>>> =20 >>>> - kfree(cma_stats); >>>> - kobject_put(cma_kobj); >>>> + kobject_put(&cma->cma_kobj->kobj); >>>> + kfree(cma->cma_kobj); >>> >>> Freeing a null pointer? >>> >>>> + cma->cma_kobj =3D NULL; >>>> + } >>>> + kobject_put(cma_kobj_root); >>> >> >> Please try to simulate the errors and check that error path is working >> properly in the next version. >> >> Alternatively, we could remove the cma_kobj_release entirely, like Gre= g >> suggested previously, and then don't care about cleaning up at all. >=20 > Does he suggested it to remove cma_kobj_release?(Initially, I did but > was rejected from Greg) >=20 Alright, I haven't followed the previous threads fully and only saw the reply where he suggested to removed it.