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 14:08:14 -0700 |
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On 6/6/19 12:54 PM, Jason Gunthorpe wrote: > On Thu, Jun 06, 2019 at 12:44:36PM -0700, Ralph Campbell wrote: >> >> 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 >>>> +++ 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. > > wow, thanks, I'd like to also really like to send such a thing through > hmm.git - do you know who the nouveau maintainers are so we can > collaborate on patch planning this?
Ben Skeggs <bskeggs@redhat.com> is the maintainer and nouveau@lists.freedesktop.org is the mailing list for changes. I'll be sure to CC them for the patch.
>> I can also send a separate patch to then remove hmm_vma_fault() >> but I guess that should be after AMD's changes. > > Let us wait to hear back from AMD how they can consume hmm.git - I'd > very much like to get everything done in one kernel cycle! > > Regards, > Jason >
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