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b=mL2Mwe7diSVX/KfxxyWAGfowSVtU7UJ6J1r7/WhbG69WnnARMJhtSAERDBajslM4+ cdoknatsScGuCHy//1gO9VkhQg23Kw+EYntjw6Ieo+bfAbCFyJ5JT42DFAtRMIqwjS +aXyjOyK01vljYkRLoAfbk5pAAHyFk0Lw6fHrigLGG4ci9tQq1cit76i0vyOpE5JAs lT7ht7yBZgPmVlhWUJtYzHhTJGTSQHTx2oNesUYOt6kd6YL9qEaIZTlwKU4SeVx9YU G3X5OH2elPJLmgFgIueb/CLFZmJOrr/CeUla7DIEsvBsg2p3fW2Y07NAY2NANZj1/B z/pbkTq5uO6rA== Date: Tue, 11 Mar 2025 11:15:11 +0100 From: Jakub Kicinski To: "Matthew Wilcox (Oracle)" Cc: Andrew Morton , netdev@vger.kernel.org, Vlastimil Babka , linux-mm@kvack.org, Hannes Reinecke Subject: Re: [PATCH] mm: Decline to manipulate the refcount on a slab page Message-ID: <20250311111511.2531b260@kernel.org> In-Reply-To: <20250310143544.1216127-1-willy@infradead.org> References: <20250310143544.1216127-1-willy@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 3F3FC8000B X-Stat-Signature: kdobzdozjw5j98bks8jtha4jmsg7ponf X-Rspam-User: X-HE-Tag: 1741688118-110615 X-HE-Meta: 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 X7dPbUi0 4JzS0mgt0NZ3D1hQORFDYFRI8JDEE1fJTkCVa0mmgJUNxKdDgXYFZkZX+OgMH3qyDc65TToWJVUHnK1/iJ3r3VwokM64E1j0QzwQQQaUw4UrvGVv1gdJJNWKj7ier4qcNzYyvyVqlckxbu12lc2SmX2twXnzgWzNOYI3ztL2zkKxhJCxTtnXtFpQywC/uCDmJgZedDZeij4hFlL4ZCidPWJmfxJq8KdEVg7L2R+AVB/806W4uIJ+hnVTVgvRmMBdL4kinnw0HpyoDC6kznC+qxub4Mg== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, 10 Mar 2025 14:35:24 +0000 Matthew Wilcox (Oracle) wrote: > Long-term, networking needs to stop taking a refcount on the pages that > it uses and rely on the caller to hold whatever references are necessary > to make the memory stable. TBH I'm not clear on who is going to fix this. IIRC we already told NVMe people that sending slab memory over sendpage is not well supported. Plus the bug is in BPF integration, judging by the stack traces (skmsg is a BPF thing). Joy.