From mboxrd@z Thu Jan 1 00:00:00 1970 From: catalin.marinas@arm.com (Catalin Marinas) Date: Wed, 16 Nov 2016 05:39:18 -0700 Subject: [PATCH] ARM64: dma-mapping: preallocate DMA-debug hash tables in core_initcall In-Reply-To: <1479288013-30945-1-git-send-email-m.szyprowski@samsung.com> References: <1479288013-30945-1-git-send-email-m.szyprowski@samsung.com> Message-ID: <20161116123918.qzaqczaqri2hab43@localhost> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Wed, Nov 16, 2016 at 10:20:13AM +0100, Marek Szyprowski wrote: > fs_initcall is definitely too late to initialize DMA-debug hash tables, > because some drivers might get probed and use DMA mapping framework > already in core_initcall. Late initialization of DMA-debug results in > false warning about accessing memory, that was not allocated. This issue > has been observed on ARM 32bit, but the same driver can be used also on > ARM64. > > This patch moves initialization of DMA-debug to core_initcall. This is > safe from the initialization perspective. dma_debug_do_init() internally > calls debugfs functions and debugfs also gets initialised at > core_initcall(), and that is earlier than arch code in the link order, > so it will get initialized just before the DMA-debug. Do we really want to rely on the link order within an initcall level? What guarantees this? I hope someone sorts out the deferred probe or some other dependency detection mechanism to address this issue. But in the meantime I wouldn't merge a patch which relies on just the link order. -- Catalin