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h=Date:From:To:Cc:Subject:References:In-Reply-To; b=S9NHwTNDd9FQ7nrl98XA7oP4Xhhu9sW1p80y37Wvsam2MFSlFDytGjYX3OIkStyo7 p/eIxc7hR5jr2cbZSwWmhxbgkjBzYLTO6LvWXTJbV7+snMR67wQ0U1HNS9oFJ32wjw 7sU+MOjodVdh2R0vtbjB/aIIOtnk91e8foUNXT4fOlRLv4wg8Ys3wLl485NPfz+0wU Rd7Qb0/MG6//xCyA6jZeM8iCaSWF61OaxIfh64qEzZCouvk9Zx9765Icn/gjxsFDSv 1MdwCH+mN0HGa1n0dOoAExjIEb2LBKn48i4fdPQc4BE80KpoCJxc/f8pqA6DlHlBrH etCJDghhLcyTw== Date: Mon, 10 Aug 2026 09:14:04 -0700 From: Eric Biggers To: Christoph Hellwig Cc: linux-block@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Jens Axboe , Vlastimil Babka , Harry Yoo , Andrew Morton , Hao Li , Christoph Lameter , David Rientjes , Roman Gushchin Subject: Re: [PATCH 2/3] mm: support fallible mempool_alloc_bulk() Message-ID: <20260810161404.GA1930@sol> References: <20260806221031.79050-1-ebiggers@kernel.org> <20260806221031.79050-3-ebiggers@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Queue-Id: E989F100011 X-Stat-Signature: uni65ktcc8jiib1deg1jaqp9jdqrtbmf X-Rspam-User: X-Rspamd-Server: rspam04 X-HE-Tag: 1786378567-280141 X-HE-Meta: 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 AnVM+Q9H 6s+zZKhnZAJUzyYawPCNmVEZoxfcDfp6fxYK04UbgF3/2EYdHhGKo64/4Wyw636JF/0gQQVblpTPE7RWUIjjuPVfYpsK3q4ADaW+17Vs0KIfjvrNBjvvw0ikcu7jQAUssGTdGqqm95stpylK0XAH/lF8Xu1Pu0DYnqEAqZ+cAqTTaRVUdrOrrO9lljv6LCvvhQyB2xnfUdf3Zv9h57SVaSuVbfwFnJA4cDmI2djDB9p2if4N9LmdBUP19uPL/sHZxCZomRrQm+l9oVCy3Ohl9Zcb6WufsBKrZxG99aD0HlqEkkiQ= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, Aug 10, 2026 at 09:00:11AM -0700, Christoph Hellwig wrote: > On Thu, Aug 06, 2026 at 03:10:30PM -0700, Eric Biggers wrote: > > To fix a deadlock, blk-crypto-fallback needs to be able to make fallible > > mempool_alloc_bulk() allocations. > > It doesn't. fallible mempool allocations are a concept that doesn't > make much sense. Please just go straight to the backing page allocator > instead for callers that do not need the mempool guarantees. It does make sense. When alloc_pages_bulk() doesn't completely succeed, there still might be pages available in the mempool. blk_crypto_alloc_enc_bio() should try to take them before falling back to scheduling the rescuer kworker. The rescuer encounters scheduling overhead and is single-threaded, so it's slow and should be used only when absolutely necessary. - Eric