On Tue, Oct 23, 2018 at 09:02:56AM -0600, Shuah Khan wrote: > Hi Michal, > > On 10/23/2018 01:23 AM, Michal Hocko wrote: > > Hi Shuah, > > > > On Mon 22-10-18 18:52:53, Uladzislau Rezki wrote: > >> On Mon, Oct 22, 2018 at 02:51:42PM +0200, Michal Hocko wrote: > >>> Hi, > >>> I haven't read through the implementation yet but I have say that I > >>> really love this cover letter. It is clear on intetion, it covers design > >>> from high level enough to start discussion and provides a very nice > >>> testing coverage. Nice work! > >>> > >>> I also think that we need a better performing vmalloc implementation > >>> long term because of the increasing number of kvmalloc users. > >>> > >>> I just have two mostly workflow specific comments. > >>> > >>>> A test-suite patch you can find here, it is based on 4.18 kernel. > >>>> ftp://vps418301.ovh.net/incoming/0001-mm-vmalloc-stress-test-suite-v4.18.patch > >>> > >>> Can you fit this stress test into the standard self test machinery? > >>> > >> If you mean "tools/testing/selftests", then i can fit that as a kernel module. > >> But not all the tests i can trigger from kernel module, because 3 of 8 tests > >> use __vmalloc_node_range() function that is not marked as EXPORT_SYMBOL. > > > > Is there any way to conditionally export these internal symbols just for > > kselftests? Or is there any other standard way how to test internal > > functionality that is not exported to modules? > > > > The way it can be handled is by adding a test module under lib. test_kmod, > test_sysctl, test_user_copy etc. The problem is that said module can only invoke functions which are exported using EXPORT_SYMBOL. And there's a cost to exporting them, which I don't think we're willing to pay, purely to get test coverage. Based on my own experience with the IDA & XArray test suites, I would like to propose a solution which does not require exporting all of these symbols: Create a new kernel module in mm/test_vmalloc.c Towards the top of that file, #include <linux/export.h> #undef EXPORT_SYMBOL #define EXPORT_SYMBOL(x) /* */ #include "vmalloc.c" Now you can invoke even static functions from your test harness.
