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Date: Tue, 6 May 2025 22:55:31 -0700
From: Kees Cook <kees@kernel.org>
To: Christoph Hellwig <hch@lst.de>
Cc: Keith Busch <kbusch@kernel.org>, kernel test robot <lkp@intel.com>,
	Jens Axboe <axboe@kernel.dk>, Sagi Grimberg <sagi@grimberg.me>,
	linux-nvme@lists.infradead.org, Chaitanya Kulkarni <kch@nvidia.com>,
	linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org
Subject: Re: [PATCH] nvme-pci: Make nvme_pci_npages_prp() __always_inline
Message-ID: <202505062255.130383D3B7@keescook>
References: <20250507033536.work.088-kees@kernel.org>
 <20250507044754.GC28402@lst.de>
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In-Reply-To: <20250507044754.GC28402@lst.de>

On Wed, May 07, 2025 at 06:47:54AM +0200, Christoph Hellwig wrote:
> On Tue, May 06, 2025 at 08:35:40PM -0700, Kees Cook wrote:
> > The only reason nvme_pci_npages_prp() could be used as a compile-time
> > known result in BUILD_BUG_ON() is because the compiler was always choosing
> > to inline the function. Under special circumstances (sanitizer coverage
> > functions disabled for __init functions on ARCH=um), the compiler decided
> > to stop inlining it:
> 
> Can we place just fix um to still force inlining inline functions instead
> of needing these workarounds?

Oh, I don't have the history here. Is there something about UM and
forcing off inlining?

-- 
Kees Cook