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[184.145.104.227]) by smtp.gmail.com with ESMTPSA id i23sm842088qtp.61.2021.04.28.14.24.30 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 28 Apr 2021 14:24:31 -0700 (PDT) Date: Wed, 28 Apr 2021 17:24:30 -0400 From: Peter Xu To: Hugh Dickins Cc: Axel Rasmussen , Andrea Arcangeli , Andrew Morton , Lokesh Gidra , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] userfaultfd: release page in error path to avoid BUG_ON Message-ID: <20210428212430.GA6462@xz-x1> References: <20210428180109.293606-1-axelrasmussen@google.com> <20210428183943.GH6584@xz-x1> MIME-Version: 1.0 In-Reply-To: Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=peterx@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline X-Stat-Signature: hjmzhn393q55zc1btzw8t94y4nnehfr3 X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 8B34EE000105 Received-SPF: none (redhat.com>: No applicable sender policy available) receiver=imf30; identity=mailfrom; envelope-from=""; helo=us-smtp-delivery-124.mimecast.com; client-ip=216.205.24.124 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1619645055-436562 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000129, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Wed, Apr 28, 2021 at 02:03:05PM -0700, Hugh Dickins wrote: [...] > > > + put_page(*pagep); > > > + *pagep = NULL; > > > + } > > > goto out; > > > > All "goto out" in this functions looks weird as it returns directly... so if > > you're touching this after all, I suggest we do "return -ENOMEM" directly and > > drop the "ret = -ENOMEM". > > No strong feeling either way from me on that: whichever looks best > to you. But I suspect the "ret = -ENOMEM" cannot be dropped, > because it's relied on further down too? Ah sorry I just noticed Axel didn't really touch that line.. :) So yeah please also feel free to keep it as is. If to drop it, "ret = -ENOMEM" can go as well, I think.. since all later errors should always reset variable "ret". Thanks, -- Peter Xu