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. > 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. Thanks, Kalesh > > [1] > https://sashiko.dev/#/patchset/20260924050009.19974-1-sarthak.sharma%40arm.com > > [2] > https://lore.kernel.org/all/[email protected]/
