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charset=utf-8 Content-Disposition: inline In-Reply-To: X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 80A0D140008 X-Stat-Signature: edxh51a5obrkanjjx31m6retnsb5cqox X-Rspam-User: X-HE-Tag: 1762850944-169325 X-HE-Meta: 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 qdZPWLJp s5m4F0seoDwYYFaJ0H457BOKSzWUj8TWv7qj9bSuWg2WRi4e9yu7AQH6TG1p/CeWN4P5yIJ0JyLrgC0FlJbJCDw2MBV4vuTMvjvIycL41VQv9ZcIp26VwUXUKVry4TLT2MUvoCv2UKeM2HKWBnk6T70F4pgr+7Fl1CNdxpPpHFxC//R0osIwIQRUC0Vl+fwTq9Rz5mlUpzcR4zrZhzpvcyy+ExjCOUdF62ogFAJKI0MoazWkTcljTpRBKuA== 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: List-Subscribe: List-Unsubscribe: On 2025-11-11 12:16:43 [+0900], Harry Yoo wrote: > > However, in the !CONFIG_HAVE_CMPXCHG_LOCAL case, mod_node_page_state() > > still calls local_irq_save(). Is this feasible in the PREEMPT_RT kernel? > > Hmm I was going to say it's necessary, but AFAICT we don't allocate > or free memory in hardirq context on PREEMPT_RT (that's the policy) > and so I'd say it's not necessary to disable IRQs. > > Sounds like we still want to disable IRQs only on !PREEMPT_RT on > such architectures? > > Not sure how seriously do PREEMPT_RT folks care about architectures > without HAVE_CMPXCHG_LOCAL. (riscv and loongarch have ARCH_SUPPORTS_RT > but doesn't have HAVE_CMPXCHG_LOCAL). We take things seriously and you shouldn't make assumption based on implementation. Either the API can be used as such or not. In case of mod_node_page_state(), the non-IRQ off version (__mod_node_page_state()) has a preempt_disable_nested() to ensure atomic update on PREEMPT_RT without disabling interrupts. Sebastian