On Wed 10-11-21 17:49:37, Suren Baghdasaryan wrote:

On Tue, Nov 9, 2021 at 1:10 PM Suren Baghdasaryan [off-list ref] wrote:

quoted

On Tue, Nov 9, 2021 at 12:10 PM Michal Hocko [off-list ref] wrote:

[...]

quoted

quoted

Yes, those can run concurrently. One thing I completely forgot about is
27ae357fa82b ("mm, oom: fix concurrent munlock and oom reaper unmap, v3")
which is about interaction with the munlock.

Agrh! This interaction with the munlock you mentioned requires us to
take mmap_write_lock before munlock_vma_pages_all and that prevents
__oom_reap_task_mm from running concurrently with unmap_vmas. The
reapers would not be as effective as they are now after such a change
:(

__oom_reap_task_mm will not run concurrently with unmap_vmas even
with the current code. The mmap_sem barrier right before munlock code
prevents that.

-- 
Michal Hocko
SUSE Labs