Re: [PATCH 2/3] mm: page table check

On Sat, Nov 27, 2021 at 3:41 AM Fusion Future [off-list ref] wrote:

It seems after updating to linux-next-20211125, my system is crashing
frequently due to "kernel BUG at mm/page_table_check.c:101".

Thank you for reporting this issue:

 99                 if (anon) {
100                         BUG_ON(atomic_read(&ptc->file_map_count));
101                         BUG_ON(atomic_dec_return(&ptc->anon_map_count) < 0);

This BUG_ON checks that during unmap anon map counter (cleared in
ptep_clear_flush()) does not become negative. If it becomes negative
it means that we missed accounting for this anon mapping during
set_pte(). Is there a config and environment that I could use to repro
this problem?

Thank you,
Pasha