On 03/05/2018 02:31 PM, Dave Hansen wrote:
On 03/05/2018 01:14 PM, Khalid Aziz wrote:
Are you suggesting that vma returned by find_vma() could be split or
merged underneath me if I do not hold mmap_sem and thus make the flag
check invalid? If so, that is a good point.
This part does make me think that this code hasn't been tested very
thoroughly. Could you describe the testing that you have done? For MPX
and protection keys, I added something to tools/testing/selftests/x86,
for instance.
This code was tested by a QA team and I ran a number of tests myself. I
wrote tests to exercise all of the API, induce exceptions for
invalid/illegal accesses and swapping was tested by allocating memory
2-4 times of the system RAM available across 4-8 threads and
reading/writing to this memory with ADI enabled. QA team wrote unit
tests to test each API with valid and invalid combinations of arguments
to the API. Stress tests that allocate and free ADI tagged memory were
also run. A version of database server was created that uses ADI tagged
memory for in-memory copy of database to test database workload. 100's
of hours of tests were run across these tests over the last 1+ year
these patches have been under review for. Cover letter includes
description of most of these tests. This code has held up through all of
these tests. It is entirely feasible some race conditions have not been
uncovered yet, just like any other piece of software. Pulling this code
into mainline kernel and having lot more people exercise this code will
help shake out any remaining issues.
Thanks,
Khalid
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