Messages in this thread | | | Subject | Re: [PATCH 4/5] mm/hmm: hmm_vma_fault() doesn't always call hmm_range_unregister() | From | Ralph Campbell <> | Date | Thu, 6 Jun 2019 12:44:36 -0700 |
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On 6/6/19 7:50 AM, Jason Gunthorpe wrote: > On Mon, May 06, 2019 at 04:29:41PM -0700, rcampbell@nvidia.com wrote: >> From: Ralph Campbell <rcampbell@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 <rcampbell@nvidia.com> >> Signed-off-by: Jérôme Glisse <jglisse@redhat.com> >> Cc: John Hubbard <jhubbard@nvidia.com> >> Cc: Ira Weiny <ira.weiny@intel.com> >> Cc: Dan Williams <dan.j.williams@intel.com> >> Cc: Arnd Bergmann <arnd@arndb.de> >> Cc: Balbir Singh <bsingharora@gmail.com> >> Cc: Dan Carpenter <dan.carpenter@oracle.com> >> Cc: Matthew Wilcox <willy@infradead.org> >> Cc: Souptick Joarder <jrdr.linux@gmail.com> >> Cc: Andrew Morton <akpm@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.GB16845@ziepe.ca/ > > So Ralph, you'll need to resend this. > > Thanks, > Jason >
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