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Thu, 12 Dec 2024 07:21:29 -0800 (PST) Received: from localhost ([193.86.92.181]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-436255531dasm19430415e9.8.2024.12.12.07.21.28 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 12 Dec 2024 07:21:28 -0800 (PST) Date: Thu, 12 Dec 2024 16:21:28 +0100 From: Michal Hocko To: Sebastian Sewior Cc: Alexei Starovoitov , Matthew Wilcox , bpf , Andrii Nakryiko , Kumar Kartikeya Dwivedi , Andrew Morton , Peter Zijlstra , Vlastimil Babka , Steven Rostedt , Hou Tao , Johannes Weiner , shakeel.butt@linux.dev, Thomas Gleixner , Tejun Heo , linux-mm , Kernel Team Subject: Re: [PATCH bpf-next v2 1/6] mm, bpf: Introduce __GFP_TRYLOCK for opportunistic page allocation Message-ID: References: <20241210023936.46871-1-alexei.starovoitov@gmail.com> <20241210023936.46871-2-alexei.starovoitov@gmail.com> <20241212150744.dVyycFUJ@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20241212150744.dVyycFUJ@linutronix.de> X-Rspamd-Queue-Id: 166D380017 X-Stat-Signature: wpxe69seqf1zckc1ykgdaf6gns3g391b X-Rspam-User: X-Rspamd-Server: rspam11 X-HE-Tag: 1734016843-612802 X-HE-Meta: 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 fJEeYeQo RHld17n5nX8ylVGiJcv2uMGlLu+lrv9wHhSq+zs+PjOt1l4q+EYcDPLvrQ9HuBLRJSPjTARS8XnbrXqv6A4czKX5wdOm/oB4mZ9y7z4k1T2EFq4MOCdfALHbLsUQhJysrcLjsfotv6IDuc8XlfSELdicok4lOGlVZXeLPaps8po+GaO14mpVs7NGT1bU1nFvHzyatP4n437AbZX6DnbdccWavE35uDbEPtstwDo8o5YxcJquyFK9w2txh4CfJ4ECSL3zS4TLQFwEoy4P79ArQzC3MCvMLZXavNSPk37+s5jdkL4Gnpj7RgXIxpfG6S4RDcoftAnCElG77mqqQdghDq6C3XK11vjD0sDesNjRS4Cjunk2kU9lgnJB7IZnAnGwV0TVZzQJXXilfTOfWXlHV2LVBxKTPkpAMbbMZQjzbh+t4i3M= X-Bogosity: Ham, tests=bogofilter, spamicity=0.014430, 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 Thu 12-12-24 16:07:44, Sebastian Sewior wrote: > But since I see in_nmi(). You can't trylock from NMI on RT. The trylock > part is easy but unlock might need to acquire rt_mutex_base::wait_lock > and worst case is to wake a waiter via wake_up_process(). Ohh, I didn't realize that. So try_lock would only be safe on raw_spin_lock right? -- Michal Hocko SUSE Labs