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McKenney" Cc: b.a.t.m.a.n@lists.open-mesh.org, Dmitry Antipov , netdev@vger.kernel.org, rcu@vger.kernel.org Subject: Re: [PATCH] Revert "batman-adv: prefer kfree_rcu() over call_rcu() with free-only callbacks" Message-ID: References: <20240612133357.2596-1-linus.luessing@c0d3.blue> <020489fa-26a3-422c-8924-7dc71f23422c@paulmck-laptop> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <020489fa-26a3-422c-8924-7dc71f23422c@paulmck-laptop> X-Last-TLS-Session-Version: TLSv1.3 Message-ID-Hash: M4NV7PYDWHYJMY3QRLML7FEJOFNTS2LR X-Message-ID-Hash: M4NV7PYDWHYJMY3QRLML7FEJOFNTS2LR X-MailFrom: linus.luessing@c0d3.blue X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; emergency; loop; banned-address; member-moderation; header-match-b.a.t.m.a.n.lists.open-mesh.org-0; header-match-b.a.t.m.a.n.lists.open-mesh.org-1; header-match-b.a.t.m.a.n.lists.open-mesh.org-2; nonmember-moderation; administrivia; implicit-dest; max-recipients; max-size; news-moderation; no-subject; digests; suspicious-header X-Mailman-Version: 3.3.8 Precedence: list List-Id: The list for a Better Approach To Mobile Ad-hoc Networking Archived-At: List-Archive: List-Help: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: On Wed, Jun 12, 2024 at 09:06:25AM -0700, Paul E. McKenney wrote: > We are looking into nice ways of solving this, but in the meantime, > yes, if you are RCU-freeing slab objects into a slab that is destroyed > at module-unload time, you currently need to stick with call_rcu() > and rcu_barrier(). > > We do have some potential solutions to allow use of kfree_rcu() with > this sort of slab, but they are still strictly potential. > > Apologies for my having failed to foresee this particular trap! > > Thanx, Paul No worries, thanks for the help and clarification! This at least restored my sanity, was starting to doubt my understanding of RCU and the batman-adv code the longer I tried to find the issue in batman-adv :D.