From de4ee728465f7c0c29241550e083139b2ce9159c Mon Sep 17 00:00:00 2001
From: Christoph Hellwig <hch@lst.de>
Date: Wed, 24 Jul 2019 08:52:55 +0200
Subject: [PATCH] nouveau: unlock mmap_sem on all errors from
nouveau_range_fault
Currently nouveau_svm_fault expects nouveau_range_fault to never unlock
mmap_sem, but the latter unlocks it for a random selection of error
codes. Fix this up by always unlocking mmap_sem for non-zero return values
in nouveau_range_fault, and only unlocking it in the caller for successful
returns.
Link: https://lore.kernel.org/r/20190724065258.16603-5-hch@lst.de
Tested-by: Ralph Campbell <rcampbell@nvidia.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jason Gunthorpe <jgg@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
---
drivers/gpu/drm/nouveau/nouveau_svm.c | 11 ++++++-----
1 file changed, 6 insertions(+), 5 deletions(-)
diff --git a/drivers/gpu/drm/nouveau/nouveau_svm.c b/drivers/gpu/drm/nouveau/nouveau_svm.c
index e3097492b4ad..a835cebb6d90 100644
--- a/drivers/gpu/drm/nouveau/nouveau_svm.c
+++ b/drivers/gpu/drm/nouveau/nouveau_svm.c
@@ -495,8 +495,10 @@ nouveau_range_fault(struct hmm_mirror *mirror, struct hmm_range *range)
ret = hmm_range_register(range, mirror,
range->start, range->end,
PAGE_SHIFT);
- if (ret)
+ if (ret) {
+ up_read(&range->vma->vm_mm->mmap_sem);
return (int)ret;
+ }
if (!hmm_range_wait_until_valid(range, HMM_RANGE_DEFAULT_TIMEOUT)) {
up_read(&range->vma->vm_mm->mmap_sem);
@@ -505,10 +507,9 @@ nouveau_range_fault(struct hmm_mirror *mirror, struct hmm_range *range)
ret = hmm_range_fault(range, true);
if (ret <= 0) {
- if (ret == -EBUSY || !ret) {
- up_read(&range->vma->vm_mm->mmap_sem);
+ if (ret == 0)
ret = -EBUSY;
- }
+ up_read(&range->vma->vm_mm->mmap_sem);
hmm_range_unregister(range);
return ret;
}
@@ -706,8 +707,8 @@ again:
NULL);
svmm->vmm->vmm.object.client->super = false;
mutex_unlock(&svmm->mutex);
+ up_read(&svmm->mm->mmap_sem);
}
- up_read(&svmm->mm->mmap_sem);
/* Cancel any faults in the window whose pages didn't manage
* to keep their valid bit, or stay writeable when required.