From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C73CE3F65F9; Tue, 14 Jul 2026 12:25:00 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784031913; cv=none; b=llRhd4PTbEyoSsYfXVONngcRpjxcz1gHl3isV84dutzLtybzHgtKN3uaQxOxAa0szIEGuPI0wz4qREWN91+xJPcsRXBwLGvQxNpu6mGNSbFkiPQakGE70i9TaiuZSJwZ9huUD7aVb+kZ+/zSIH8CbzP+vJ6R0FSlLG06dy6Ie6M= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784031913; c=relaxed/simple; bh=X+zhc8g0fJVudjV8pFBtpHMZsTT4XVawhNZEoqTcuW8=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=ZqRNBKh26w7jYTcU8XCmYHmS6hJ5F/6zDwgEDoVVbxDIUyxzNOcbTBesnFGCqkzpUU0PS/vVeqabPcdVb2qgElZdZNP7v8Ly7m4rrbYHR/Pt+3foECp4LTa5A8HveU4J7GxcX1gmfmQoUsVDTa0tOAftEJ7U/4Ek8CXN5wtmsWM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Uk8LCrfd; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Uk8LCrfd" Received: by smtp.kernel.org (Postfix) with ESMTPSA id AB38A1F00A3A; Tue, 14 Jul 2026 12:24:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1784031899; bh=ncHjbQ9ufoT6SdeAfwRC2oHP5TMeYh9A0isrkQOo65c=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=Uk8LCrfdl+bpQBeTpDRh0oc+8+a48aSIelbqzRi4zcYvWLX8sL8PxBp5hbaMZ0N9Y nVwiwe5noR2fo5n8OoliuzsH7AN/eZRgcnZMxx4vJk4UrEIUqUa6k2idnbK9QgHqXj MvcdH/lQE7Be/UpQwxNPD6F6RDv4kQpNEWdShdefAKU7jb+xKA44rV4fWKT8iKCIpd oYq5git6zMaT/Ydsw25+f41mpCLw8kebEFGA22uBE3LXWKxb4zzlWHCYg2aA4NMASc 6KhnkAFxAiN3+HQ57h5wBLKt+VIJv0+/x3+ocfej2PJIAOaCgDGi2/izTJw36B81t0 qYENoTSEHp4mg== Date: Tue, 14 Jul 2026 15:24:56 +0300 From: Leon Romanovsky To: "Mike Rapoport (Microsoft)" Cc: Jason Gunthorpe , Dennis Dalessandro , linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-rdma@vger.kernel.org Subject: Re: [PATCH v2 0/5] RDMA, IB: replace __get_free_pages() with kmalloc() Message-ID: <20260714122456.GD19233@unreal> References: <20260713-b4-rdma-v2-0-65d2a1a5180c@kernel.org> Precedence: bulk X-Mailing-List: linux-rdma@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260713-b4-rdma-v2-0-65d2a1a5180c@kernel.org> On Mon, Jul 13, 2026 at 10:17:21AM +0300, Mike Rapoport (Microsoft) wrote: > This is a (small) part of larger work of replacing page allocator calls > with kmalloc. > > My initial intention a few month ago was to remove ugly casts [1], but then > willy pointed out that Linus objected to something like this [2] and it > looks like more than a decade old technical debt. > > Largely, anything that doesn't need struct page (or a memdesc in the > future) should just use kmalloc() or kvmalloc() to allocate memory. > kmalloc() guarantees alignment, physical contiguity and working > virt_to_phys() and beside nicer API that returns void * on alloc and > doesn't require to know the allocation size on free, kmalloc() provides > better debugging capabilities than page allocator. > > Another thing is that touching these allocation sites gives the reviewers > opportunity to see if a PAGE_SIZE buffer is actually needed or maybe > another size is appropriate. > > For larger allocations that don't need physically contiguous memory > kvmalloc() can be a better option that __get_free_pages() because under > memory pressure it's is easier to allocate several order-0 pages than a > physically contiguous chunk with the same number of pages. > > And last, but not least, removing needless calls to page allocator should > help with memdesc (aka project folio) conversion. There will be way less > places to audit to see if the user was actually using struct page. > > Also in git: > https://git.kernel.org/pub/scm/linux/kernel/git/rppt/linux.git gfp-to-kmalloc/rdma Will you also change get_zeroed_page() in RDMA, or should I prepare a patch? Thanks > > [1] https://lore.kernel.org/all/20251018093002.3660549-1-rppt@kernel.org/ > [2] https://lore.kernel.org/all/CA+55aFwp4iy4rtX2gE2WjBGFL=NxMVnoFeHqYa2j1dYOMMGqxg@mail.gmail.com/ > > --- > v2 changes: > * add comment to keep markers for sites that need "fast and as large as > possible" allocation helper > > v1: https://patch.msgid.link/20260630-b4-rdma-v1-0-ab42bcf0de92@kernel.org > > --- > Mike Rapoport (Microsoft) (5): > RDMA/umem: ib_umem_get(): use kmalloc() to allocate page array > RDMA/mlx5: replace __get_free_page() with kmalloc() > IB/mthca: mthca_reg_user_mr(): use kmalloc() to allocate addresses array > IB/mthca: allocate mthca_array memory with kzalloc() > IB/rdmavt: use kzalloc() to allocate QPN-map pages > > drivers/infiniband/core/umem.c | 5 +++-- > drivers/infiniband/hw/mlx5/odp.c | 6 ++++-- > drivers/infiniband/hw/mthca/mthca_allocator.c | 6 +++--- > drivers/infiniband/hw/mthca/mthca_provider.c | 5 +++-- > drivers/infiniband/sw/rdmavt/qp.c | 8 ++++---- > 5 files changed, 17 insertions(+), 13 deletions(-) > --- > base-commit: dc59e4fea9d83f03bad6bddf3fa2e52491777482 > change-id: 20260610-b4-rdma-44625922fe16 > > -- > Sincerely yours, > Mike. >