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Howlett" , Vlastimil Babka , Mike Rapoport , Michal Hocko Subject: Re: [PATCH RFC v3 2/4] exec: introduce struct task_exec_state Message-ID: References: <20260520-work-task_exec_state-v3-0-69f895bc1385@kernel.org> <20260520-work-task_exec_state-v3-2-69f895bc1385@kernel.org> <20260526-halbieren-badeverbot-maler-d4bf1a6ea119@brauner> MIME-Version: 1.0 In-Reply-To: <20260526-halbieren-badeverbot-maler-d4bf1a6ea119@brauner> X-Scanned-By: MIMEDefang 3.0 on 10.30.177.12 X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: h9Rcv8OME-Rb4j1qzVQwLC0u8GKENcvZT0Sje6sLX8E_1779783462 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 0CE3040005 X-Stat-Signature: jyydcf9zzjzbqq98d3ysh74ykbug5mi8 X-Rspam-User: X-HE-Tag: 1779783470-824207 X-HE-Meta: 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 wefu5zv6 sJ4gwZ8aeJgQSM5t5eGbR1PWwGAsN/M3Wl7T7zTQOaZGrJoM94QAues5PsSA6x+1o06miOQxC8Tkax+Vic9/2JDjQLbv4Fv0r/VnMHHD9RDeGodY5aU/k4BJaEcAMTnEoDR9FcN6aW/EQbDZmbHf2630S6y5qUdY6Td6Vzn+DvRUICEQQgFXSrSJ26rK6KRORN4gD3wjlfPHYrGwwv9tnBcTJyHisYzwni7XUKaDHZrtNiNUoAZQtebYZE+fAnDkaHJHqCseNCEvWn7FrjB/7UAEj3AbnMPjPBi0XFXnZvk+nB2pIdNjr6xlN2U/b5Xru+89mbr0rZrO7l5do588yFiTlyj6xwqm47Sr33oGqzl966oL7CNYl/ih5WLpdxN2PvsmI+n2B8Ezg5/ocUvkm3wBsJrxHocwO7fHbE/Bexavf6VMXNFjmST+VfD4Wv1CROv06 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 05/26, Christian Brauner wrote: > > On Fri, May 22, 2026 at 05:00:10PM +0200, Oleg Nesterov wrote: > > > > Can't we (later) move exec_state into signal_struct? > > > > AFAICS, the only complication is that task_still_dumpable/etc can't use > > tsk->signal->exec_state if tsk was alredy reaped (another thread can do > > exec_mmap() after that). But perhaps we can rely on pid_alive() check > > and return an error if the task has already passed __unhash_process() ? > > So Jann pointed out a problem with this in > https://lore.kernel.org/CAG48ez0Gz_GghVeVzaixAQRNYBdWHYEj3K6FXBSzc+8WNsFxtA@mail.gmail.com Aha, thanks. This is basically what I have said above. > I quote: > > I think signal_struct is not unshared on exec; so in this sequence of events: > > - task T1 is a non-dumpable task > - task T1 creates another thread T2 > - T2 exits > - T1 goes through execve and becomes dumpable Note that T1 can call exec_mmap/etc only after T2 is already reaped, that is why I said we need to use something like pid_alive() check. OK, lets forget it for now, this needs some changes in release_task() path, perhaps makes no sense. FWIW, your series + additional fixlets you sent in reply to 0/4 look good to me, I see nothing wrong. Oleg.