On Mon, Jan 23, 2017 at 04:33:08PM +0000, Catalin Marinas wrote: > On Mon, Jan 23, 2017 at 05:15:39PM +0100, Geert Uytterhoeven wrote: > > On Mon, Jan 23, 2017 at 5:02 PM, <gregkh@xxxxxxxxxxxxxxxxxxx> wrote: > > > This is a note to let you know that I've just added the patch titled > > > > > > arm64: Fix swiotlb fallback allocation > > > > > > to the 4.9-stable tree which can be found at: > > > http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary > > > > > > The filename of the patch is: > > > arm64-fix-swiotlb-fallback-allocation.patch > > > and it can be found in the queue-4.9 subdirectory. > > > > > > If you, or anyone else, feels it should not be added to the stable tree, > > > please let <stable@xxxxxxxxxxxxxxx> know about it. > > > > > > > > > From 524dabe1c68e0bca25ce7b108099e5d89472a101 Mon Sep 17 00:00:00 2001 > > > From: Alexander Graf <agraf@xxxxxxx> > > > Date: Mon, 16 Jan 2017 12:46:33 +0100 > > > Subject: arm64: Fix swiotlb fallback allocation > > > > > > From: Alexander Graf <agraf@xxxxxxx> > > > > > > commit 524dabe1c68e0bca25ce7b108099e5d89472a101 upstream. > > > > > > Commit b67a8b29df introduced logic to skip swiotlb allocation when all memory > > > is DMA accessible anyway. > > > > > > While this is a great idea, __dma_alloc still calls swiotlb code unconditionally > > > to allocate memory when there is no CMA memory available. The swiotlb code is > > > called to ensure that we at least try get_free_pages(). > > > > > > Without initialization, swiotlb allocation code tries to access io_tlb_list > > > which is NULL. That results in a stack trace like this: > > > > > > Unable to handle kernel NULL pointer dereference at virtual address 00000000 > > > [...] > > > [<ffff00000845b908>] swiotlb_tbl_map_single+0xd0/0x2b0 > > > [<ffff00000845be94>] swiotlb_alloc_coherent+0x10c/0x198 > > > [<ffff000008099dc0>] __dma_alloc+0x68/0x1a8 > > > [<ffff000000a1b410>] drm_gem_cma_create+0x98/0x108 [drm] > > > [<ffff000000abcaac>] drm_fbdev_cma_create_with_funcs+0xbc/0x368 [drm_kms_helper] > > > [<ffff000000abcd84>] drm_fbdev_cma_create+0x2c/0x40 [drm_kms_helper] > > > [<ffff000000abc040>] drm_fb_helper_initial_config+0x238/0x410 [drm_kms_helper] > > > [<ffff000000abce88>] drm_fbdev_cma_init_with_funcs+0x98/0x160 [drm_kms_helper] > > > [<ffff000000abcf90>] drm_fbdev_cma_init+0x40/0x58 [drm_kms_helper] > > > [<ffff000000b47980>] vc4_kms_load+0x90/0xf0 [vc4] > > > [<ffff000000b46a94>] vc4_drm_bind+0xec/0x168 [vc4] > > > [...] > > > > > > Thankfully swiotlb code just learned how to not do allocations with the FORCE_NO > > > option. This patch configures the swiotlb code to use that if we decide not to > > > initialize the swiotlb framework. > > > > > > Fixes: b67a8b29df ("arm64: mm: only initialize swiotlb when necessary") > > > Signed-off-by: Alexander Graf <agraf@xxxxxxx> > > > CC: Jisheng Zhang <jszhang@xxxxxxxxxxx> > > > CC: Geert Uytterhoeven <geert+renesas@xxxxxxxxx> > > > CC: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx> > > > Signed-off-by: Catalin Marinas <catalin.marinas@xxxxxxx> > > > Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> > > > > > > --- > > > arch/arm64/mm/init.c | 2 ++ > > > 1 file changed, 2 insertions(+) > > > > > > --- a/arch/arm64/mm/init.c > > > +++ b/arch/arm64/mm/init.c > > > @@ -403,6 +403,8 @@ void __init mem_init(void) > > > { > > > if (swiotlb_force || max_pfn > (arm64_dma_phys_limit >> PAGE_SHIFT)) > > > swiotlb_init(1); > > > + else > > > + swiotlb_force = SWIOTLB_NO_FORCE; > > > > The above definition depends on: > > > > commit ae7871be189cb411 ("swiotlb: Convert swiotlb_force from int to enum") > > commit fff5d99225107f5f ("swiotlb: Add swiotlb=noforce debug option") > > If these are not suitable for stable (too big, new feature), we can just > drop the arm64 commit from 4.9-stable (and we could fix it in a > different way). Those look fine, I've queued them up now (took a bit of manual work), and will let the autobuilder have fun with it... thanks, greg k-h -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html