Patch "drm/nouveau/mmu: ALIGN_DOWN correct variable" has been added to the 4.15-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    drm/nouveau/mmu: ALIGN_DOWN correct variable

to the 4.15-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:
     drm-nouveau-mmu-align_down-correct-variable.patch
and it can be found in the queue-4.15 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From da5e45e619b3f101420c38b3006a9ae4f3ad19b0 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?M=C4=81ris=20Narti=C5=A1s?= <maris.nartiss@gmail.com>
Date: Fri, 16 Mar 2018 11:38:43 +1000
Subject: drm/nouveau/mmu: ALIGN_DOWN correct variable

From: Māris Nartišs <maris.nartiss@gmail.com>

commit da5e45e619b3f101420c38b3006a9ae4f3ad19b0 upstream.

Commit 7110c89bb8852ff8b0f88ce05b332b3fe22bd11e ("mmu: swap out round
for ALIGN") replaced two calls to round/rounddown with ALIGN/ALIGN_DOWN,
but erroneously applied ALIGN_DOWN to a different variable (addr) and left
intended variable (tail) not rounded/ALIGNed.

As a result screen corruption, X lockups are observable. An example of kernel
log of affected system with NV98 card where it was bisected:

nouveau 0000:01:00.0: gr: TRAP_M2MF 00000002 [IN]
nouveau 0000:01:00.0: gr: TRAP_M2MF 00320951 400007c0 00000000 04000000
nouveau 0000:01:00.0: gr: 00200000 [] ch 1 [000fbbe000 DRM] subc 4 class 5039
mthd 0100 data 00000000
nouveau 0000:01:00.0: fb: trapped read at 0040000000 on channel 1
[0fbbe000 DRM]
engine 00 [PGRAPH] client 03 [DISPATCH] subclient 04 [M2M_IN] reason 00000006
[NULL_DMAOBJ]

Fixes bug 105173 ("[MCP79][Regression] Unhandled NULL pointer dereference in
nvkm_object_unmap since kernel 4.15")
https://bugs.freedesktop.org/show_bug.cgi?id=105173

Fixes: 7110c89bb885 ("mmu: swap out round for ALIGN ")
Tested-by: Pierre Moreau <pierre.morrow@free.fr>
Reviewed-by: Pierre Moreau <pierre.morrow@free.fr>
Signed-off-by: Maris Nartiss <maris.nartiss@gmail.com>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
Cc: stable@vger.kernel.org # v4.15+
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmm.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmm.c
+++ b/drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmm.c
@@ -1354,7 +1354,7 @@ nvkm_vmm_get_locked(struct nvkm_vmm *vmm
 
 		tail = this->addr + this->size;
 		if (vmm->func->page_block && next && next->page != p)
-			tail = ALIGN_DOWN(addr, vmm->func->page_block);
+			tail = ALIGN_DOWN(tail, vmm->func->page_block);
 
 		if (addr <= tail && tail - addr >= size) {
 			rb_erase(&this->tree, &vmm->free);


Patches currently in stable-queue which might be from maris.nartiss@gmail.com are

queue-4.15/drm-nouveau-mmu-align_down-correct-variable.patch