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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-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260511_144412_550562_C2BFCD4F X-CRM114-Status: GOOD ( 13.42 ) X-BeenThere: kexec@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "kexec" Errors-To: kexec-bounces+kexec=archiver.kernel.org@lists.infradead.org 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