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 15D44379C51 for ; Tue, 12 May 2026 07:10:17 +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=1778569818; cv=none; b=M5VVckzlcGFnFbwRXIFb6+PxCQ7EMQmOPqqzsj2f8nr4fIXvS76WIdENfMTWXq+cjkj+thGDInsjPHwFn3L7IibTH3YJJnVNS4eCr9Rydv+AkStKpmuWjKH7b2RK+o6mEGfeTl0wdRCxyb7eNdU9i+IY+3TAYCRKgiqK1GqvvpQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778569818; c=relaxed/simple; bh=XNVtpyNdEPMz9RZWRmkotNxiv3tY3VuFlQj6D3gMlLc=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=MUZeD/22YVV9v8BHsSptzopxvHrWS/YK8aaHiIPUz4VqcnaOXoYLJvNBPmgE1hJEOsZ9Ll3LfWEJGzcvHzKDgrsrdrYIxkzdRJfiXVC/vLHmkV0OTcWiDieHiXRT3t0yJp/EcG1CcWQmWb1VyBu87btKczB99fhSuSpfxD9pOwo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=cLRw+7cl; 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="cLRw+7cl" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6A1F3C2BCB0; Tue, 12 May 2026 07:10:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1778569816; bh=XNVtpyNdEPMz9RZWRmkotNxiv3tY3VuFlQj6D3gMlLc=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=cLRw+7cl+9cdptzw5B0TJs+eVQI6KNHpNxhbNu59cOj5zv0ksg/VvrUjqhsWANLuz zLrNYc4+wW2+PH5MwkAUxmT2MeM4lmCNrUslqav5Zs0OuvWZiAxku3qZwZrDhzXQAd 8/jhZeuf7XkOiBePezl2a7FHz7i7/TNiiX6BuicS+a+pMw6o5i5xHcqQUKoF4qVVbL P/Bd0FBoiErsrlxLWmnE0vuzWVa3gmxwpLrhEpWwcKy7qIYk1Bsmr7mszlq0BMgCw4 JafmoBlldikEJLEeMEIa4mnq8BhsRcAlnEJ3FugpDx4BX+29Uyr9x9iFlknr7CdnT1 YvQbgyTZ6kiCw== Message-ID: <7ac55082-aca9-4f77-a9d9-b2ca9b606f20@kernel.org> Date: Tue, 12 May 2026 09:10:14 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] resource: export iomem_get_mapping() for loadable modules To: Ravi Kumar Bandi , hch@infradead.org Cc: akpm@linux-foundation.org, bhelgaas@google.com, djbw@kernel.org, ilpo.jarvinen@linux.intel.com, linux-kernel@vger.kernel.org References: <20260511161643.30662-1-ravib@amazon.com> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 5/11/26 18:16, Ravi Kumar Bandi wrote: > On Mon, May 11, 2026 at 00:17:45 -0700, Christoph Hellwig wrote: >> And why? > > On Mon, May 11, 2026 at 09:14:04 +0200, David Hildenbrand wrote: >> Which in-tree driver wants to make use of this? > > Thank you both for reviewing the patch. > > Currently this is needed by a PCIe endpoint driver that handles surprise > removal on a device without a hot-plug pin routed to the CPU. The link-down > event is detected by the in-tree Xilinx DMA PL PCIe controller driver > (drivers/pci/controller/pcie-xilinx-dma-pl.c), which notifies the endpoint > driver via the link-down callback. > > When link-down is detected, the endpoint driver needs to zap existing > userspace BAR mappings (mmap'd via sysfs resource files) to deliver SIGBUS > rather than leaving stale mappings to a dead device, preventing kernel > crashes on subsequent accesses. > > unmap_mapping_range() is already EXPORT_SYMBOL'd for this purpose > (mm/memory.c), but without iomem_get_mapping() being exported, loadable > modules cannot use it correctly for PCI BAR mappings, forcing ugly > workarounds such as walking all process VMAs. Okay, so you essentially want to implement something similar to revoke_iomem()? -- Cheers, David