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;
set_max_mapnr(pfn_to_page(max_pfn) - mem_map);
Patches currently in stable-queue which might be from agraf@xxxxxxx are
queue-4.9/arm64-fix-swiotlb-fallback-allocation.patch
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