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[209.85.167.47]) by smtp.gmail.com with ESMTPSA id w20sm1943354ljo.68.2020.06.12.12.46.41 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 12 Jun 2020 12:46:41 -0700 (PDT) Received: by mail-lf1-f47.google.com with SMTP id h188so6123477lfd.7 for ; Fri, 12 Jun 2020 12:46:41 -0700 (PDT) X-Received: by 2002:a19:ae0f:: with SMTP id f15mr7711925lfc.142.1591991201362; Fri, 12 Jun 2020 12:46:41 -0700 (PDT) MIME-Version: 1.0 References: <875zc8kxyg.fsf@x220.int.ebiederm.org> <87zh9atx0x.fsf@x220.int.ebiederm.org> <871rmkozf5.fsf_-_@x220.int.ebiederm.org> In-Reply-To: <871rmkozf5.fsf_-_@x220.int.ebiederm.org> From: Linus Torvalds Date: Fri, 12 Jun 2020 12:46:25 -0700 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [GIT PULL] proc fixes v2 for v5.8-rc1 To: "Eric W. Biederman" , Alexey Dobriyan , Al Viro Cc: Linux Kernel Mailing List , Alexey Gladkov Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jun 12, 2020 at 12:34 PM Eric W. Biederman wrote: > > ebiederm@xmission.com (Eric W. Biederman) writes: What happened to that first version of the email? I never got it.. > Looking at the code the fsnotify watch should have been removed by > fsnotify_sb_delete in generic_shutdown_super. Hmm. Correct. The new_inode_pseudo() is for things that don't have quotas, fsnotify or writeback. That was used somewhat intentionally on /proc, though. /proc certainly doesn't have quotas or writeback. And fsnotify on /proc seems a bit questionably too. Do people actually _do_ this and depend on it, or is this just about syzbot doing something odd and thus showing the problem? Anyway, I have pulled your fix, because I think it's reasonable and safe, but I do wonder if we should have kept the new_inode_pseudo(), and instead just make fsnotify say "you can't notify on an inode that isn't on the superblock list". Hmm? Is fsnotify on /proc really sensible? Do we actually generate any useful notifications? Linus