From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 ACCCA28C2BF for ; Mon, 16 Feb 2026 06:12:21 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1771222341; cv=none; b=PeIMg4WQm31leq3dTz/TpoCJrBppfuzw3ol13ogK1siSa0TddpBOYe1Daq4RLVwkhjxZhLkSzwLMpoYfmPTh3mVVgjsZeTF9WGnOe1PXt03aRHlBKYlJxzwCC32PycGY+cCu1U4tC+JbVClS7HpnbcTCk9zlIejr0Jm0djUcbwk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1771222341; c=relaxed/simple; bh=fY+kP4YBwDjhTps+8Ev42mJuQ2PGyMnt8O2c+6gw+os=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=dn2iwyMr8H51CTgpb3VikuJRX5V2FFclHhUA7FjmsOqIPqaPHqDJ91Pj+fdVY0D394KIDvxlOQWM55v494EzTGhtHn+SlAqG2V9LhBJA+snDQ824y/0YaQ9NHOJuoXUltGxkfytP/nqqK1XoD0OxNPViz6I1gMbgsLIaeOrkkAM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=jCF5oRwf; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="jCF5oRwf" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9DA1EC116C6; Mon, 16 Feb 2026 06:12:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1771222341; bh=fY+kP4YBwDjhTps+8Ev42mJuQ2PGyMnt8O2c+6gw+os=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=jCF5oRwfkYA1Au/svGJjtPKb1knHldnWQ2zJ/Xfr8HkSCgzajCCy+V4/nLHuCsrLZ G7Dw7l+8pTDQ+XjNNxw1E7RViBYQTlhfy+GbamI85/vBQAWgGBxr550bub17NutpBt V0+qsZ8jro6pUERz9qOcIP7SIeIqUDrRYRBf6lRBcOO8HDJEykJRKDxjIc/WMnrlyE fKw3N5qqk6oODa4zxXgREKxEuni2FvBtmepwBhzFixRaWyWGKk/rqg+plGSaLAT/Wa XgxaHjDfMbBAo1E0uT2Lu9uuNdWgBhjd5YLb4LQ+hB5NsxibRi/FeVu8mCqHhSotA0 Q5RO9Sk5/LORg== Date: Mon, 16 Feb 2026 11:42:14 +0530 From: Sumit Garg To: Matthew Wilcox Cc: op-tee@lists.trustedfirmware.org, jens.wiklander@linaro.org, vbabka@suse.cz, akpm@linux-foundation.org, linux-kernel@vger.kernel.org, Sumit Garg , Marco Felsch , Sven =?iso-8859-1?Q?P=FCschel?= Subject: Re: [RFT PATCH] tee: shm: Remove refcounting of kernel pages Message-ID: References: <20260213113317.1728769-1-sumit.garg@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=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: On Fri, Feb 13, 2026 at 04:08:57PM +0000, Matthew Wilcox wrote: > On Fri, Feb 13, 2026 at 05:03:17PM +0530, Sumit Garg wrote: > > From: Sumit Garg > > Um, this patch is exactly the patch I sent. You're stealing my > authorship! This patch should have my From: and Signed-off-by: > lines. Your role in this is "handling and transporting the patch" > (see Documentation/process/submitting-patches.rst). By all means > take credit for writing the commit message. Not sure how I can consider that diff from you a proper patch but surely I tried to give your suggestion attributes. However, it's fine with me to keep your authorship if you really want to vet this patch. Will send a v2 with the authorship updated. -Sumit > > > Earlier TEE subsystem assumed to refcount all the memory pages to be > > shared with TEE implementation to be refcounted. However, the slab > > allocations within the kernel don't allow refcounting kernel pages. > > > > It is rather better to trust the kernel clients to not free pages while > > being shared with TEE implementation. Hence, remove refcounting of kernel > > pages from register_shm_helper() API. > > > > Fixes: b9c0e49abfca ("mm: decline to manipulate the refcount on a slab page") > > Reported-by: Marco Felsch > > Reported-by: Sven Püschel > > Suggested-by: Matthew Wilcox > > Signed-off-by: Sumit Garg > > --- > > drivers/tee/tee_shm.c | 29 +---------------------------- > > 1 file changed, 1 insertion(+), 28 deletions(-) > > > > diff --git a/drivers/tee/tee_shm.c b/drivers/tee/tee_shm.c > > index 4a47de4bb2e5..54e2ba3afb25 100644 > > --- a/drivers/tee/tee_shm.c > > +++ b/drivers/tee/tee_shm.c > > @@ -23,29 +23,11 @@ struct tee_shm_dma_mem { > > struct page *page; > > }; > > > > -static void shm_put_kernel_pages(struct page **pages, size_t page_count) > > -{ > > - size_t n; > > - > > - for (n = 0; n < page_count; n++) > > - put_page(pages[n]); > > -} > > - > > -static void shm_get_kernel_pages(struct page **pages, size_t page_count) > > -{ > > - size_t n; > > - > > - for (n = 0; n < page_count; n++) > > - get_page(pages[n]); > > -} > > - > > static void release_registered_pages(struct tee_shm *shm) > > { > > if (shm->pages) { > > if (shm->flags & TEE_SHM_USER_MAPPED) > > unpin_user_pages(shm->pages, shm->num_pages); > > - else > > - shm_put_kernel_pages(shm->pages, shm->num_pages); > > > > kfree(shm->pages); > > } > > @@ -477,13 +459,6 @@ register_shm_helper(struct tee_context *ctx, struct iov_iter *iter, u32 flags, > > goto err_put_shm_pages; > > } > > > > - /* > > - * iov_iter_extract_kvec_pages does not get reference on the pages, > > - * get a reference on them. > > - */ > > - if (iov_iter_is_kvec(iter)) > > - shm_get_kernel_pages(shm->pages, num_pages); > > - > > shm->offset = off; > > shm->size = len; > > shm->num_pages = num_pages; > > @@ -497,10 +472,8 @@ register_shm_helper(struct tee_context *ctx, struct iov_iter *iter, u32 flags, > > > > return shm; > > err_put_shm_pages: > > - if (!iov_iter_is_kvec(iter)) > > + if (iter_is_uvec(iter)) > > unpin_user_pages(shm->pages, shm->num_pages); > > - else > > - shm_put_kernel_pages(shm->pages, shm->num_pages); > > err_free_shm_pages: > > kfree(shm->pages); > > err_free_shm: > > -- > > 2.51.0 > >