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Mon, 03 Apr 2023 13:40:06 -0700 (PDT) MIME-Version: 1.0 References: In-Reply-To: From: Yosry Ahmed Date: Mon, 3 Apr 2023 13:39:29 -0700 Message-ID: Subject: Re: [PATCH v2 4/9] cgroup: rstat: add WARN_ON_ONCE() if flushing outside task context To: Michal Hocko Cc: Johannes Weiner , Shakeel Butt , Tejun Heo , Josef Bacik , Jens Axboe , Zefan Li , Roman Gushchin , Muchun Song , Andrew Morton , =?UTF-8?Q?Michal_Koutn=C3=BD?= , Vasily Averin , cgroups@vger.kernel.org, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, bpf@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Queue-Id: DFB101C0010 X-Rspamd-Server: rspam09 X-Rspam-User: X-Stat-Signature: b9kdti8tq1f1fxpxhpqq8coky888fypd X-HE-Tag: 1680554407-257023 X-HE-Meta: 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 p7LsHdm+ mllfx5yhLxQ11Lw5lEnOqkTtzqwE/MUbbAAR++btsuGp49cCpuvGeqJ5yPsr85NlRaekjK22aKLNZp6Sijy1xjn1EGqgyTgHkIjzzsyqW0w0E/cDMCAkDPmkXu5wSqrJC05g5Qi/b+imq73oec7cu1tzwJCnAKEqfgFtGp1j/HQojMdqIKUIlhKlZM6Iz7DpUnSyLOs36Vp5dCMMb/7Qd6IRN1z7rsUZ7rIBf9H5R6xk5Wr6bcAhQM7diMpk5ILgmWSkdbbvv97SQIsPNgBIRImsfYW3hucic3gO1ZfNII8kc38zOoFk15oJk4de1moke0/vEDnj15Jui0gKCGv+wCJknwiqWQxWJ9cq/ 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 Mon, Apr 3, 2023 at 1:38=E2=80=AFAM Michal Hocko wrote= : > > On Fri 31-03-23 12:03:47, Yosry Ahmed wrote: > > On Fri, Mar 31, 2023 at 4:02=E2=80=AFAM Michal Hocko = wrote: > > > > > > On Thu 30-03-23 01:53:38, Yosry Ahmed wrote: > > > [...] > > > > Maybe we can add a primitive like might_sleep() for this, just food= for thought. > > > > > > I do not think it is the correct to abuse might_sleep if the function > > > itself doesn't sleep. If it does might_sleep is already involved. > > > > Oh, sorry if I wasn't clear, I did not mean to reuse might_sleep() -- > > I meant introducing a new similar debug primitive that shouts if irqs > > are disabled. > > This is circling back to original concerns about arbitrary decision to > care about IRQs. Is this really any different from spin locks or preempt > disabled critical sections preventing any scheduling and potentially > triggereing soft lockups? Not really, I am sure there are other code paths that may cause similar problems. At least we can start annotating them so that we don't regress them (e.g. by introducing a caller that disables irqs -- converting them into hard lockups). > -- > Michal Hocko > SUSE Labs