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[172.10.233.147]) by smtp.gmail.com with ESMTPSA id n11-20020a9d710b000000b005af4ceeaac1sm6905945otj.37.2022.03.13.19.40.19 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 13 Mar 2022 19:40:19 -0700 (PDT) Date: Sun, 13 Mar 2022 19:40:08 -0700 (PDT) From: Hugh Dickins X-X-Sender: hugh@ripple.anvils To: Miaohe Lin cc: akpm@linux-foundation.org, Herbert.van.den.Bergh@oracle.com, chris.mason@oracle.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm/mlock: fix potential imbalanced rlimit ucounts adjustment In-Reply-To: <20220310132417.41189-1-linmiaohe@huawei.com> Message-ID: <268b3146-2963-15b6-6d6-95a96853314@google.com> References: <20220310132417.41189-1-linmiaohe@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 5550E18001D Authentication-Results: imf16.hostedemail.com; dkim=pass header.d=google.com header.s=20210112 header.b=MsndYsoW; spf=pass (imf16.hostedemail.com: domain of hughd@google.com designates 209.85.167.179 as permitted sender) smtp.mailfrom=hughd@google.com; dmarc=pass (policy=reject) header.from=google.com X-Rspam-User: X-Stat-Signature: ajjgazo686snzngcnat8hi55pqnbixsf X-HE-Tag: 1647225621-570766 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 Thu, 10 Mar 2022, Miaohe Lin wrote: > user_shm_lock forgets to set allowed to 0 when get_ucounts fails. So > the later user_shm_unlock might do the extra dec_rlimit_ucounts. Fix > this by resetting allowed to 0. > > Fixes: 5ed44a401ddf ("do not limit locked memory when RLIMIT_MEMLOCK is RLIM_INFINITY") > Signed-off-by: Miaohe Lin NAK. user_shm_lock() remembers to declare "int allowed = 0" on entry. > --- > mm/mlock.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/mm/mlock.c b/mm/mlock.c > index 29372c0eebe5..efd2dd2943de 100644 > --- a/mm/mlock.c > +++ b/mm/mlock.c > @@ -733,6 +733,7 @@ int user_shm_lock(size_t size, struct ucounts *ucounts) > } > if (!get_ucounts(ucounts)) { > dec_rlimit_ucounts(ucounts, UCOUNT_RLIMIT_MEMLOCK, locked); > + allowed = 0; > goto out; > } > allowed = 1; > -- > 2.23.0 > > >