Re: [PATCH v3 0/2] selftests/cgroup: fixes for test_zswap on single core VM

[Andrew Morton]

On Thu, 27 Aug 2026 03:47:40 +0000 Wilson Felipe Pereira <wfelipe@xxxxxxxxxx> wrote:

> This series fixes two test failures in test_zswap observed when running on
> a single-core VM (-smp 1) with 4GB of RAM.
> 
> Patch 1 addresses a race condition in test_zswap_writeback() where
> waitpid() returns before the exiting child process is switched away by the
> kernel, causing an immediate write of "+memory" to cgroup.subtree_control
> to fail with -EBUSY. We fix this by waiting for cgroup.events to report
> "populated 0".
> 
> Patch 2 fixes an implicit unsigned conversion bug in test_no_kmem_bypass()
> where small negative timing differences between debugfs stored_pages and
> cgroup zswapped bytes caused the comparison to falsely fail due to
> unsigned promotion.

Thanks.  Sashiko thinks there remain some
signedness/truncation/overflow issues in there:

	https://sashiko.dev/#/patchset/20260827034807.2822234-1-wfelipe@xxxxxxxxxx