| Message ID | 1484567193-71258-1-git-send-email-agraf@suse.de (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Mon, Jan 16, 2017 at 12:46:33PM +0100, Alexander Graf wrote: > 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@suse.de> > CC: Catalin Marinas <catalin.marinas@arm.com> > CC: Jisheng Zhang <jszhang@marvell.com> > CC: Geert Uytterhoeven <geert+renesas@glider.be> > CC: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Queued for 4.10. Thanks.
diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c index 716d122..380ebe7 100644 --- a/arch/arm64/mm/init.c +++ b/arch/arm64/mm/init.c @@ -404,6 +404,8 @@ void __init mem_init(void) if (swiotlb_force == SWIOTLB_FORCE || max_pfn > (arm64_dma_phys_limit >> PAGE_SHIFT)) swiotlb_init(1); + else + swiotlb_force = SWIOTLB_NO_FORCE; set_max_mapnr(pfn_to_page(max_pfn) - mem_map);
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@suse.de> CC: Catalin Marinas <catalin.marinas@arm.com> CC: Jisheng Zhang <jszhang@marvell.com> CC: Geert Uytterhoeven <geert+renesas@glider.be> CC: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> --- arch/arm64/mm/init.c | 2 ++ 1 file changed, 2 insertions(+)