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Wed, 24 Mar 2021 12:57:48 -0700 (PDT) Received: from google.com ([2620:15c:211:201:7dfa:1e53:536:7976]) by smtp.gmail.com with ESMTPSA id e8sm3314971pgb.35.2021.03.24.12.57.46 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 24 Mar 2021 12:57:47 -0700 (PDT) Date: Wed, 24 Mar 2021 12:57:45 -0700 From: Minchan Kim To: Dmitry Osipenko Cc: Andrew Morton , linux-mm , LKML , gregkh@linuxfoundation.org, surenb@google.com, joaodias@google.com, jhubbard@nvidia.com, willy@infradead.org Subject: Re: [PATCH] mm: cma: fix corruption cma_sysfs_alloc_pages_count Message-ID: References: <20210324192044.1505747-1-minchan@kernel.org> <18ee5c3e-fba2-0d8d-bd93-5fb8d0dd7a01@gmail.com> <89ba4c7a-42d2-5412-2367-cc1cffc1117b@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <89ba4c7a-42d2-5412-2367-cc1cffc1117b@gmail.com> X-Stat-Signature: crse58ioymg5ze5k6iucxcrjbmy6qaog X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: C9768A000388 Received-SPF: none (gmail.com>: No applicable sender policy available) receiver=imf24; identity=mailfrom; envelope-from=""; helo=mail-pg1-f180.google.com; client-ip=209.85.215.180 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1616615867-400085 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: 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; > >=20 > >> while (--i >=3D 0) { > >=20 > > Do you realize that this doesn't work anymore? > >=20 > >> 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); > >=20 > > Freeing a null pointer? > >=20 > >> + cma->cma_kobj =3D NULL; > >> + } > >> + kobject_put(cma_kobj_root); > >=20 >=20 > Please try to simulate the errors and check that error path is working > properly in the next version. >=20 > Alternatively, we could remove the cma_kobj_release entirely, like Greg > suggested previously, and then don't care about cleaning up at all. Does he suggested it to remove cma_kobj_release?(Initially, I did but was rejected from Greg)