Re: [PATCH] fs/ceph/addr: always call ceph_shift_unused_folios_left()

On Thu, Sep 4, 2025 at 11:43 PM Viacheslav Dubeyko Slava.Dubeyko@ibm.com wrote:

By applying the patch [1], enabling CONFIG_DEBUG_VM, and returning -E2BIG from ceph_check_page_before_write(), I was able to reproduce this warning:

Thanks, I'm glad you could verify the bug and my fix. In case this wasn't clear: you saw just a warning, but this is usually a kernel crash due to NULL pointer dereference. If you only got a warning but no crash, it means your test VM does not use transparent huge pages (no huge_zero_folio allocated yet). In a real workload, the kernel would have crashed.