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 3EB5F374A1B; Sat, 29 Aug 2026 10:35:17 +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=1787999720; cv=none; b=PHwizCRbtxqnfxrs1O2xS54E1RsX5WvO1LpaLAq4UPY/PY2ImWzHEb4UTY/X8knRgAvTM3KydWALtnWHXWssZBF8rtXAWNmwJXU6Imf8qFGXGkAbWOMdgajJy8PbmAxyGR7T83RITID5C8z9g2l8aPrNsXI8wKN+1JH0oVEwa7A= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787999720; c=relaxed/simple; bh=TMjEM4qL8n/RjmKlbHGpaQh+OEsEcOVV0nLrPlTqzYE=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=p9jPfLir8i/3dH69+GpApKaIwf71GPmL0zxEpfphxg0iOu+tcaj4uhr7dJP4+YotuZdYtRs8B+Nh7iBl/IJTfScCAUY9G6uAzQeNL16FGhnpr+YG6380mCbBNM/vyWnjBaQRcucxNhyyvHu/2tEVJavFPauGfCloKK32NHaXhBU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=O4hQnDvs; 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="O4hQnDvs" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1854E1F000E9; Sat, 29 Aug 2026 10:35:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1787999716; bh=2cSRCs8wDnCpBsS5x9/4R2NQI4neq/3EffewAPnRfKA=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=O4hQnDvsR3xz25zX0vx3nLmgtgXidRy0h4sWYehV2mXaWQF9J/8/dCttJ+E6EWeiL AU5vXmX8gEuh+eiBybVN36gcL9arMMcSOSmanqnA1H0jUHcst2QpkRCuZYvOQ1utna CmwIa3FMYIznrNaOU5idsntYbhRRO3HxdH82sL2QSmZq4KSQ//9h/0e1+1QzkyWNZ0 0rU3vqxq8xzjrVdcdZh5qOVfsw3iXccSIzOadiD6bqnoMbprP3lZK1UtNz4gXJHS5C 0O9KudEm0w62SpmKO8x56+dxacucnGq4B3gGwuAtRjfi6EA2/TmEU4oUb4c3BtwI86 LMFxBKkcdwmyA== Date: Sat, 29 Aug 2026 13:35:09 +0300 From: Mike Rapoport To: "Martin K. Petersen" Cc: Brian King , Hannes Reinecke , "James E.J. Bottomley" , Matthew Wilcox , Wen Xiong , linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-scsi@vger.kernel.org, target-devel@vger.kernel.org, Hannes Reinecke , John Garry Subject: Re: [PATCH v2 0/4] scsi: replace __get_free_pages() with kmalloc() Message-ID: References: <20260704-b4-scsi-v2-0-7d2d21a810de@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@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: <20260704-b4-scsi-v2-0-7d2d21a810de@kernel.org> Hi Martin, This seems to fall between the cracks. Do you want me to resend? On Sat, Jul 04, 2026 at 09:13:33AM +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/scsi > > [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: > * replace GFP_ATOMIC with GFP_NOIO in ipr driver > > v1: https://patch.msgid.link/20260630-b4-scsi-v1-0-494fb37ebe7b@kernel.org > > --- > Mike Rapoport (Microsoft) (4): > scsi: target: file: use kmalloc() to allocate temporary protection buffer > scsi: proc: use kmalloc() in proc writers > scsi: ipr: use kmalloc() to allocate IPR dump buffer memory > scsi: sym53c8xx_2: replace __get_free_pages() with kmalloc() > > drivers/scsi/ipr.c | 4 ++-- > drivers/scsi/scsi_devinfo.c | 5 +++-- > drivers/scsi/scsi_proc.c | 9 +++++---- > drivers/scsi/sym53c8xx_2/sym_hipd.h | 4 ++-- > drivers/target/target_core_file.c | 4 ++-- > 5 files changed, 14 insertions(+), 12 deletions(-) > --- > base-commit: dc59e4fea9d83f03bad6bddf3fa2e52491777482 > change-id: 20260611-b4-scsi-d0b0eb4895f4 > > -- > Sincerely yours, > Mike. > -- Sincerely yours, Mike.