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 9966E30102A; Thu, 14 Aug 2025 13:31:12 +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=1755178272; cv=none; b=g8zFdVo48f/97Me72M75iKVgRdlI5WWOh5DR5ymKe3DeBdBp2ynk53GX3b6e///v8GD/5VxfI4ZaAm/vkw3y6MJww7gd0ng/Nc20ExYsk4fCESnAaY4zCfF5u3TmELC7rNHB5EbJ+nuBfmEo8CYac7NYPcgl0hqtrSyOHrMatPA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755178272; c=relaxed/simple; bh=WW0xB1u8XI1L1gGsXl6wpt3WDXrr4yCiJlHi7BUNlCY=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=lfTHyC6OQOJEZXS6SAD9hh7yr+1ioL+EpNjkick9LIJdmdPF0pri4gAv8r6f/XfFPFFO0x8wt1d5+zSJSb+mHsKE5uz8sXW7uD6v9zS4O34Ptp9Cu7TakTbW7mZiV/goXUgA+xgQbtlB83dH+g99MMzxaQmkv1slMKqhE4yvAiE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=XqHxW8YW; 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="XqHxW8YW" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 02E81C4CEF1; Thu, 14 Aug 2025 13:31:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1755178272; bh=WW0xB1u8XI1L1gGsXl6wpt3WDXrr4yCiJlHi7BUNlCY=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=XqHxW8YW58Ln/tIjnGi73wY9qD5/Iqkzwyv6qop3T0s5v319Ftg/c1ujK3/+Pmp3O 3SJY9d+x4hq26C9R4ldz3ap27JZ3CK6dbddTXlBk+z2z09uVrOYjtUFTpeGlFvgNjV L1huyBWZL3RmFzTXcCZe8HHfxLc3AApxz5Ss7QLL+ussS/TR5qi1rfohz3kzvuYQXA z9fOR+m/fazEworlcK45UcqDrJLI+rHyeuLbz0YS0ZizqgTQFWAKE1JSOTRnlpXZlF 3y7wTMxm2dgJYYjVCyrbQbIxiWn20GP+y7nUAEOT4RU14M4Kgk2W8/qCK/ckcjXpyq NVGeZpIDI1XVQ== Date: Thu, 14 Aug 2025 16:31:06 +0300 From: Leon Romanovsky To: Jason Gunthorpe Cc: Marek Szyprowski , Abdiel Janulgue , Alexander Potapenko , Alex Gaynor , Andrew Morton , Christoph Hellwig , Danilo Krummrich , iommu@lists.linux.dev, Jason Wang , Jens Axboe , Joerg Roedel , Jonathan Corbet , Juergen Gross , kasan-dev@googlegroups.com, Keith Busch , linux-block@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-nvme@lists.infradead.org, linuxppc-dev@lists.ozlabs.org, linux-trace-kernel@vger.kernel.org, Madhavan Srinivasan , Masami Hiramatsu , Michael Ellerman , "Michael S. Tsirkin" , Miguel Ojeda , Robin Murphy , rust-for-linux@vger.kernel.org, Sagi Grimberg , Stefano Stabellini , Steven Rostedt , virtualization@lists.linux.dev, Will Deacon , xen-devel@lists.xenproject.org Subject: Re: [PATCH v1 08/16] kmsan: convert kmsan_handle_dma to use physical addresses Message-ID: <20250814133106.GE310013@unreal> References: <5b40377b621e49ff4107fa10646c828ccc94e53e.1754292567.git.leon@kernel.org> <20250807122115.GH184255@nvidia.com> <20250813150718.GB310013@unreal> <20250814121316.GC699432@nvidia.com> <20250814123506.GD310013@unreal> <20250814124448.GE699432@nvidia.com> Precedence: bulk X-Mailing-List: linux-trace-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: <20250814124448.GE699432@nvidia.com> On Thu, Aug 14, 2025 at 09:44:48AM -0300, Jason Gunthorpe wrote: > On Thu, Aug 14, 2025 at 03:35:06PM +0300, Leon Romanovsky wrote: > > > Then check attrs here, not pfn_valid. > > > > attrs are not available in kmsan_handle_dma(). I can add it if you prefer. > > That makes more sense to the overall design. The comments I gave > before were driving at a promise to never try to touch a struct page > for ATTR_MMIO and think this should be comphrensive to never touching > a struct page even if pfnvalid. > > > > > So let's keep this patch as is. > > > > > > Still need to fix the remarks you clipped, do not check PageHighMem > > > just call kmap_local_pfn(). All thie PageHighMem stuff is new to this > > > patch and should not be here, it is the wrong way to use highmem. > > > > Sure, thanks > > I am wondering if there is some reason it was written like this in the > first place. Maybe we can't even do kmap here.. So perhaps if there is > not a strong reason to change it just continue to check pagehighmem > and fail. > > if (!(attrs & ATTR_MMIO) && PageHighMem(phys_to_page(phys))) > return; Does this version good enough? There is no need to call to kmap_local_pfn() if we prevent PageHighMem pages. diff --git a/mm/kmsan/hooks.c b/mm/kmsan/hooks.c index eab7912a3bf0..d9cf70f4159c 100644 --- a/mm/kmsan/hooks.c +++ b/mm/kmsan/hooks.c @@ -337,13 +337,13 @@ static void kmsan_handle_dma_page(const void *addr, size_t size, /* Helper function to handle DMA data transfers. */ void kmsan_handle_dma(phys_addr_t phys, size_t size, - enum dma_data_direction dir) + enum dma_data_direction dir, unsigned long attrs) { u64 page_offset, to_go, addr; struct page *page; void *kaddr; - if (!pfn_valid(PHYS_PFN(phys))) + if ((attrs & ATTR_MMIO) || PageHighMem(phys_to_page(phys))) return; page = phys_to_page(phys); @@ -357,19 +357,12 @@ void kmsan_handle_dma(phys_addr_t phys, size_t size, while (size > 0) { to_go = min(PAGE_SIZE - page_offset, (u64)size); - if (PageHighMem(page)) - /* Handle highmem pages using kmap */ - kaddr = kmap_local_page(page); - else - /* Lowmem pages can be accessed directly */ - kaddr = page_address(page); + /* Lowmem pages can be accessed directly */ + kaddr = page_address(page); addr = (u64)kaddr + page_offset; kmsan_handle_dma_page((void *)addr, to_go, dir); - if (PageHighMem(page)) - kunmap_local(page); - phys += to_go; size -= to_go; (END) > > Jason >