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AJvYcCXvGN4/x072NhOLmm2Dnlie5KfETwM4iwKTrenqd13Egu4yqF5j6grkW8gMfodEIf4STubjutEryQ==@kvack.org X-Gm-Message-State: AOJu0Yz1dMmc29HoJ9Xc73DwQlkIFMUisGZX+GffRIfGasy8AwvqRPts po35UFXZGJQA6sHIdlJXMQ23LLWDjyg26MdqHsysI9iU/rKzkP3VzoRUYjJ+vPaf6xh0CStu6Ni g8e1C4kc83tS9pQhAsudtleYzasGKwIE= X-Gm-Gg: ASbGncu8qINTscmiMDbvQHw9QcILTHY7XBMYO/y76sW7xTIkNRBVP/cRrWAfRbErBYu ax1s8O5y4pCaPXA/aGAf05WNy6R3S6PoYstIUaYX/w3Mheb/soG6WFDDOX0BV3+z6QzjaYM+bfS IjrJO261fR2xbAooJQZV/7P7XZ5hkFu1aARKfmFjVFvng+tAheD3iqeRaEgmc3Loy7i5j4RUXBT qwQJvGjN4mujD9QNAkOqg7G7KiFzvDhYdj5 X-Google-Smtp-Source: AGHT+IEr/Zm4Pxly+Efbv6sNYcUut7LfEU4UTikXIVrxYEdaISjLHguHk43hV30oxPl4SaJojIG0lHAi9h0Ph0jNBHQ= X-Received: by 2002:a05:600c:450f:b0:45d:d8d6:7fcc with SMTP id 5b1f17b1804b1-46206a2b929mr28099785e9.27.1758134460571; Wed, 17 Sep 2025 11:41:00 -0700 (PDT) MIME-Version: 1.0 References: <20250916022140.60269-1-alexei.starovoitov@gmail.com> <47aca3ca-a65b-4c0b-aaff-3a7bb6e484fe@suse.cz> <0beac436-1905-4542-aebe-92074aaea54f@suse.cz> In-Reply-To: From: Alexei Starovoitov Date: Wed, 17 Sep 2025 11:40:49 -0700 X-Gm-Features: AS18NWCKkOmsGuqHqNCm235rRDn6_iVaWC-ke90mDrNQHKL2y4zWb_MZh87_Ljw Message-ID: Subject: Re: [PATCH slab] slab: Disallow kprobes in ___slab_alloc() To: Vlastimil Babka Cc: Harry Yoo , bpf , linux-mm , Shakeel Butt , Michal Hocko , Sebastian Sewior , Andrii Nakryiko , Kumar Kartikeya Dwivedi , Andrew Morton , Peter Zijlstra , Steven Rostedt , Johannes Weiner Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Stat-Signature: ubxbqjba796556o4c8exsmpoxrwxmakr X-Rspam-User: X-Rspamd-Queue-Id: 18426C000E X-Rspamd-Server: rspam04 X-HE-Tag: 1758134461-698841 X-HE-Meta: U2FsdGVkX1/pLhlHnGHupB/P7Y/Z+LWg6vEuXJ3z3qYxxgZeidsB6PB+jrTVl9/KWuti/8pJPajGelZGwUa3BcHINMGdewGCwTo0bghxqpgVwfzjZ7eHTSsxPnhyQSQRDNNfkSd+gZnqaS0B75N1X3iTXmbChx1HtiQibDJ7wYXvYBZg4ikmCkuWW0mW70IM2IEkHyEESiz75NTS/2AtXOIi+WPSXZS0BNvieAUhGuTrEutXbkKS/KEPtS5oIOTHkOqwz87JQmmc4hd26NX23wkCazr/D8Zk8dEuY4dlGsMYuXCU1zYHc7yxVHgdDROB5sNNG5wR/qMYS4/s6RQe0xH8yzp0VmHB8CAMJNB8X3V9jiISlUhZOq8K5HDf3VN5tvbQOlx/68UdjhAifvhtpMp1cO+ba+u5eRxVOPqznXG8QU4IJ8ZanDB0Jby7wGj04OirStH5UcVZa7nLdVdwxbyq43zpiTamgb+1qeM7or0cJTpgKn9MQjy4qztuM0XkT63dKAr21LWLe3WH2RpjdJDEupib53dkWrBlZbsbHzQVEVsTM2yjvEPjQfETN58QvzYOKCvg75Oi4t+ODgAnUuSonYkDkh0BxnBnlI/HwIa7mpi8RtmjFofs7dXscVzCg2Nmw6MwNcHQsvNcmP2TTiHgETW4loTV5Hawrxj1vDLYrw6Zl+QbIr97dtiMjG/NrA8r3KdxQWweBFAdRlE3/oZ3wLC/bscv1n499LA4vSs94Lvh7bnuhNS+S8gJnOuic0y3v8PlwBDDI6/SJh1mwmWWdnY6PProRd94GZ1qAJXeyd9/k8Gts1WtAWPkxZt4PS176pYCja+yaL+UqK5+NZYBNyr2N5X7ApZtFsj4PLUNSJbsWIzWuqFgWXfiLYk0kqfQGWbqbcWjE69/IcVH9OuXCnMWIvEBNkxGcQRoDyL+hV/FbdX+3cpA8+lNBbHoGtPkvixTD0xXmPceq/a CuZZ8IiE 17QaT+/eYymb61ibas28jLyFGH5aAh2ekeuI43ICSrEEHUKqO0pnlKg6zbw== 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 Wed, Sep 17, 2025 at 11:34=E2=80=AFAM Vlastimil Babka w= rote: > > > Ah right, I did add one based on your commit log and this conversation: > > +/* > + * We disallow kprobes in ___slab_alloc() to prevent reentrance > + * > + * kmalloc() -> ___slab_alloc() -> local_lock_cpu_slab() protected part = of > + * ___slab_alloc() manipulating c->freelist -> kprobe -> bpf -> > + * kmalloc_nolock() or kfree_nolock() -> __update_cpu_freelist_fast() > + * manipulating c->freelist without lock. > + * > + * This does not prevent kprobe in functions called from ___slab_alloc()= such as > + * local_lock_irqsave() itself, and that is fine, we only need to protec= t the > + * c->freelist manipulation in ___slab_alloc() itself. > + */ > +NOKPROBE_SYMBOL(___slab_alloc); Perfect. Short and to the point. Thanks!