On 9/29/26 09:32, Kalesh Singh wrote: > On Mon, Sep 28, 2026 at 10:54 PM Sarthak Sharma <[email protected]> > wrote: >> >> >> >> On 9/24/26 10:30 AM, Sarthak Sharma wrote: >>> This series fixes several correctness issues in mremap_test and >>> simplifies and strengthens its data validation. >>> >>> Patch 1 converts the mremap_test to use kselftest helpers, removes >>> manual tracking of failed tests and corrects some spelling errors. >>> >>> Patches 2 to 5 fix userfaultfd skipping, unexpected mremap success >>> handling, multi-VMA data validation and failure reporting when data >>> corruption is detected. >>> >>> Patch 6 removes the randomization and uses a simple pattern based approach. >>> >>> Patch 7 removes perf tests and timing infrastructure. >>> >>> Patch 8 removes validation threshold and always validates complete mappings. >>> >>> Patch 9 strengthens the multi VMA validation by also checking the >>> mapping state of holes after remapping. >> >> Hello everyone! Just wanted to check if someone has had a chance to look >> at the series. >> >> Also, Sashiko has a concern [1], and I had the same while posting the >> series. I hope I can get some opinion from the community. >> >> Currently, for PUD remap tests, we allocate a source mapping of 2GB. We >> only fault in the first threshold_mb amount of memory, remap the whole >> region, and validate the already faulted threshold_mb amount of memory, >> which is, by default, equal to 4MB and can be changed by the user by >> supplying a command line option. >> >> Since we plan to remove all command line options from teh selftests, I >> removed threshold_mb altogether, following some discussion on the list >> [2]. This would now cause a 2GB source mapping, and its contents copied >> from another 2GB buffer. This causes the process to have a 4GB RSS.
Yeah, that's a lot for small CI systems indeed. >> Sashiko says that this can cause OOM killing in small CI machines. >> >> Would it be okay to keep a 4GB RSS in this case, or should we find some >> other way of validating a part of the whole range instead? > > Hi Sarthak, > > IIRC when I initially introduced the test, John was concerned that > validating the whole range would significantly increase the duration > of the mm selftests; this is why the threshold was introduced. Please > check how much it increases if we validate the full range (with > David's suggestions) and if it's no longer a concern from other folks. > I am fine with removing the threshold. As discussed off-list, I guess it makes more sense to validate a couple of pages at the beginning, the middle and the end? -- Cheers, David
