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Mon, 21 Sep 2026 09:58:19 -0700 (PDT) Received: from localhost ([2a03:2880:2ff:57::]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-3a0673b7f31sm188197a91.4.2026.09.21.09.58.19 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 21 Sep 2026 09:58:19 -0700 (PDT) Date: Mon, 21 Sep 2026 09:58:18 -0700 Message-ID: <7286d84a0b3b4098219acc0cf9803e6e@gmail.com> From: Stanislav Fomichev To: netdev-bot+sashiko@kernel.org Cc: netdev@vger.kernel.org, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, horms@kernel.org, sdf@fomichev.me, bobbyeshleman@meta.com, almasrymina@google.com, linux-kernel@vger.kernel.org In-Reply-To: <178993807798.2160803.6987249829072277558@kernel.org> Subject: Re: Re: [PATCH net-next v3 1/3] net: devmem: replace gen_pool with freelist Content-Type: text/plain; charset="utf-8" Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: > gen_pool_free() -> gen_pool_free_owner() -> bitmap_clear_ll() > BUG_ON(remain); > > Reaching this requires a separate page_pool refcount bug, since > mp_dmabuf_devmem_release_page() rejects refcount != 1, so this is > only a loss of a fail-stop diagnostic. Is dropping that check > intentional to match io_uring zcrx, which uses the same unguarded > LIFO? Working as intended. A duplicate return already violates page_pool ownership. > This is a pre-existing issue and not introduced here, since the > return value of page_pool_set_dma_addr_netmem() is dropped. > > Would it be worth failing the bind here as well? I plan to follow up with 2 more patches to cleanup freelist and will fix it there (convert to the helpers). Let's consider this a pre-existing issue that I'll fix separately? > [Severity: Medium] > Can this walk overrun owner->area.niovs[], binding->freelist[] and > binding->tx_vec[]? > > Would adding the sum check or the post-loop equality check be > worthwhile? Same feedback as on patch 1: let's not do defensive programming. We do have a contract where dmabuf->len == sum(sg->len) and it is maintained for the in-tree dmabufs.