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[34.150.200.138]) by smtp.gmail.com with ESMTPSA id 00721157ae682-7bd6686ead7sm150263157b3.39.2026.05.11.06.44.08 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 11 May 2026 06:44:09 -0700 (PDT) Date: Mon, 11 May 2026 09:44:08 -0400 From: Pasha Tatashin To: Pratyush Yadav Cc: Pasha Tatashin , rppt@kernel.org, sourabhjain@linux.ibm.com, jbouron@amazon.com, akpm@linux-foundation.org, linux-mm@kvack.org, bhe@redhat.com, linux-kernel@vger.kernel.org, dan.carpenter@linaro.org, rafael.j.wysocki@intel.com, piliu@redhat.com, kexec@lists.infradead.org, graf@amazon.com, changyuanl@google.com, mario.limonciello@amd.com Subject: Re: [PATCH v2 3/3] liveupdate: block outgoing session mutations Message-ID: References: <20260506182039.2623553-5-pasha.tatashin@soleen.com> <20260506182039.2623553-8-pasha.tatashin@soleen.com> <2vxzv7cucint.fsf@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <2vxzv7cucint.fsf@kernel.org> X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 100921C0010 X-Rspam-User: X-Stat-Signature: q7i6w6hc69ppgqdhs8dmgnyrdi3jj11n X-HE-Tag: 1778507050-149180 X-HE-Meta: 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 E6eIfhN4 3hR4j+opmL2YOQ8DjcLlxb5eknt2XBt9SFz1rfb6nDPLT8Che8SM7s4YT49ms9lT0jHYfuNMUxnYlMZdPvu6dg8wuxI0zXpcNRyCiiPjErd6p5Yb5vJEubp3nMiM6y0z+azeMT2a8KGJbWEDgYj39XsE1NwUD9icTdajDRXJGJNOSb6EYrZyPiDmdSsPDCBY7axoGSywwFQlezcCUObTB9Zy0ctNIkcEWlI6ONDI3jTJbsc1DV3uNydSiyW28uuDCITtFibZHuPGojjogbnuq2Ld0/ePsfVhpiCRrcKEhIeARSmjVWEx4PT4eGV4kBZXUvXfqeGLizxIs6K2GsQtt/QMIFWLWn5xu4Ni0ZFCwBzJiekA4vVHqP716MB3/ypvEaYuduweMuvxoSJY= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 05-11 13:03, Pratyush Yadav wrote: > On Wed, May 06 2026, Pasha Tatashin wrote: > > > During the reboot() syscall, user processes may still be running > > concurrently and attempting to mutate sessions (e.g., adding files or > > closing sessions). To prevent this, hold the session header's rwsem and > > each session's mutex indefinitely on successful serialization. > > > > If serialization succeeds, these locks will never be released as the > > system transitions to the new kernel, effectively blocking any > > concurrent task attempting to modify or release a session. If > > liveupdate_reboot() fails, the locks are released in the error path, > > allowing normal operation to resume. > > > > Fixes: 0153094d03df ("liveupdate: luo_session: add sessions support") > > Reported-by: Oskar Gerlicz Kowalczuk > > Signed-off-by: Pasha Tatashin > > Reviewed-by: Pratyush Yadav (Google) Sashiko also provided a good comment about this patch: We run over MAX_LOCK_DEPTH limit with this patch. I am going to refactor to not take every session lock simultaneously during serialization. > > [...] > > -- > Regards, > Pratyush Yadav