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References: <55684262-1dab-503a-eb4a-f030b6fcc57e@gmail.com> To: kernelnewbies@kernelnewbies.org From: Taeung Song X-Forwarded-Message-Id: <55684262-1dab-503a-eb4a-f030b6fcc57e@gmail.com> Message-ID: <8b29c7f0-8dd2-1355-f9b5-99dcb0e046e0@gmail.com> Date: Wed, 20 May 2020 18:38:42 +0900 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 MIME-Version: 1.0 In-Reply-To: <55684262-1dab-503a-eb4a-f030b6fcc57e@gmail.com> Content-Language: en-US X-Mailman-Approved-At: Wed, 27 May 2020 14:04:18 -0400 X-BeenThere: kernelnewbies@kernelnewbies.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Learn about the Linux kernel List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Errors-To: kernelnewbies-bounces@kernelnewbies.org Hi, After reading arch/x86/entry/entry_64.S I think preemption is checked only when returning from interrupt (not exception like syscall) Is is right ? (based on x86) All scenario of checking for preemption in my opinion: (1) check kernel preemption after interrupt https://github.com/torvalds/linux/blob/master/arch/x86/entry/entry_64.S#L672 (2) check user preemption after interrupt https://github.com/torvalds/linux/blob/master/arch/x86/entry/entry_64.S#L620 prepare_exit_to_usermode() -> exit_to_usermode_loop() -> if (cached_flags & _TIF_NEED_RESCHED) schedule(); Thanks, Taeung _______________________________________________ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies