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Goncalves" , Andrew Morton , Boqun Feng , Ingo Molnar , John Ogness , Mel Gorman , Michal Hocko , Petr Mladek , Thomas Gleixner , Waiman Long , Will Deacon References: <20230623171232.892937-1-bigeasy@linutronix.de> <20230623171232.892937-2-bigeasy@linutronix.de> <20230626081254.XmorFrhs@linutronix.de> <0a0c768c-227d-c0cd-1b91-5a884d161c1b@I-love.SAKURA.ne.jp> <20230626104831.GT4253@hirez.programming.kicks-ass.net> From: Tetsuo Handa In-Reply-To: <20230626104831.GT4253@hirez.programming.kicks-ass.net> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Stat-Signature: zq44nn6a9uhsrzcy37gssfxn4d7tobq9 X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: DC75414000C X-Rspam-User: X-HE-Tag: 1687778784-755158 X-HE-Meta: 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 tGd/p0Gr BkogQIDPG8rPv4ABCZbfM8uAdYXla/pn/s1w7uz6NX0dJXzFOh0DbLEG1cFOSZm3lnfW6jJ7gveVz/nYVLSosN067ZW0y3q+3qFHBZ0Wtpad2HFPQGFaLbvOLqARhYM1kU/AC4PdcPuW+hRVULX0E6lwEkB/LBtRjMsF8vItXUenJFXqzZ8Sochb2YHaJCkAaXjumrOVwbQHgA+/6V1YXvNnRdBGF0LuUpzmNpy8rp1484ntGkCX0skPFHGJwyFD8clvan/Y9N8LY7lJBl2/90zBjUunAQm9AbWtoZ9RWo8oQrpKgvcp5295Hl896H4oGbiAjPpcbb32oiVY= 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 2023/06/26 19:48, Peter Zijlstra wrote: > On Mon, Jun 26, 2023 at 06:25:56PM +0900, Tetsuo Handa wrote: >> On 2023/06/26 17:12, Sebastian Andrzej Siewior wrote: >>> On 2023-06-24 15:54:12 [+0900], Tetsuo Handa wrote: >>>> Why not to do the same on the end side? >>>> >>>> static inline void do_write_seqcount_end(seqcount_t *s) >>>> { >>>> - seqcount_release(&s->dep_map, _RET_IP_); >>>> do_raw_write_seqcount_end(s); >>>> + seqcount_release(&s->dep_map, _RET_IP_); >>>> } >>> >>> I don't have a compelling argument for doing it. It is probably better >>> to release the lock from lockdep's point of view and then really release >>> it (so it can't be acquired before it is released). >> >> We must do it because this is a source of possible printk() deadlock. >> Otherwise, I will nack on PATCH 2/2. > > Don't be like that... just hate on prink like the rest of us. In fact, > i've been patching out the actual printk code for years because its > unusable garbage. > > Will this actually still be a problem once all the fancy printk stuff > lands? That shouldn't do synchronous prints except to 'atomic' consoles > by default IIRC. Commit 1007843a9190 ("mm/page_alloc: fix potential deadlock on zonelist_update_seq seqlock") was applied to 4.14-stable trees, and CONFIG_PREEMPT_RT is available since 5.3. Thus, we want a fix which can be applied to 5.4-stable and later. This means that we can't count on all the fancy printk stuff being available.