On 6/6/19 7:50 AM, Jason Gunthorpe wrote:
On Mon, May 06, 2019 at 04:29:41PM -0700, rcampb...@nvidia.com wrote:
From: Ralph Campbell <rcampb...@nvidia.com>
The helper function hmm_vma_fault() calls hmm_range_register() but is
missing a call to hmm_range_unregister() in one of the error paths.
This leads to a reference count leak and ultimately a memory leak on
struct hmm.
Always call hmm_range_unregister() if hmm_range_register() succeeded.
Signed-off-by: Ralph Campbell <rcampb...@nvidia.com>
Signed-off-by: Jérôme Glisse <jgli...@redhat.com>
Cc: John Hubbard <jhubb...@nvidia.com>
Cc: Ira Weiny <ira.we...@intel.com>
Cc: Dan Williams <dan.j.willi...@intel.com>
Cc: Arnd Bergmann <a...@arndb.de>
Cc: Balbir Singh <bsinghar...@gmail.com>
Cc: Dan Carpenter <dan.carpen...@oracle.com>
Cc: Matthew Wilcox <wi...@infradead.org>
Cc: Souptick Joarder <jrdr.li...@gmail.com>
Cc: Andrew Morton <a...@linux-foundation.org>
---
include/linux/hmm.h | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/include/linux/hmm.h b/include/linux/hmm.h
index 35a429621e1e..fa0671d67269 100644
--- a/include/linux/hmm.h
+++ b/include/linux/hmm.h
@@ -559,6 +559,7 @@ static inline int hmm_vma_fault(struct hmm_range *range,
bool block)
return (int)ret;
if (!hmm_range_wait_until_valid(range, HMM_RANGE_DEFAULT_TIMEOUT)) {
+ hmm_range_unregister(range);
/*
* The mmap_sem was taken by driver we release it here and
* returns -EAGAIN which correspond to mmap_sem have been
@@ -570,13 +571,13 @@ static inline int hmm_vma_fault(struct hmm_range *range,
bool block)
ret = hmm_range_fault(range, block);
if (ret <= 0) {
+ hmm_range_unregister(range);
While this seems to be a clear improvement, it seems there is still a
bug in nouveau_svm.c around here as I see it calls hmm_vma_fault() but
never calls hmm_range_unregister() for its on stack range - and
hmm_vma_fault() still returns with the range registered.
As hmm_vma_fault() is only used by nouveau and is marked as
deprecated, I think we need to fix nouveau, either by dropping
hmm_range_fault(), or by adding the missing unregister to nouveau in
this patch.
I will send a patch for nouveau to use hmm_range_register() and
hmm_range_fault() and do some testing with OpenCL.
I can also send a separate patch to then remove hmm_vma_fault()
but I guess that should be after AMD's changes.
Also, I see in linux-next that amdgpu_ttm.c has wrongly copied use of
this deprecated API, including these bugs...
amd folks: Can you please push a patch for your driver to stop using
hmm_vma_fault() and correct the use-after free? Ideally I'd like to
delete this function this merge cycle from hmm.git
Also if you missed it, I'm running a clean hmm.git that you can pull
into the AMD tree, if necessary, to get the changes that will go into
5.3 - if you need/wish to do this please consult with me before making a
merge commit, thanks. See:
https://lore.kernel.org/lkml/20190524124455.gb16...@ziepe.ca/
So Ralph, you'll need to resend this.
Thanks,
Jason
