On 1/31/22 12:19, Roman Gushchin wrote:
On Mon, Jan 31, 2022 at 12:15:19PM -0500, Waiman Long wrote:
On 1/31/22 12:09, Waiman Long wrote:
On 1/31/22 12:01, Roman Gushchin wrote:
On Sun, Jan 30, 2022 at 10:55:56PM -0500, Waiman Long wrote:
On 10/1/21 19:51, Roman Gushchin wrote:
On Fri, Oct 01, 2021 at 03:09:36PM -0400, Waiman Long wrote:
When freeing a page associated with an offlined memcg, refill_stock()
will put it into local stock delaying its demise until another memcg
comes in to take its place in the stock. To avoid that, we now check
for offlined memcg and go directly in this case to the slowpath for
the uncharge via the repurposed cancel_charge() function.
Hi Waiman!
I'm afraid it can make a cleanup of a dying cgroup slower: for every
released page we'll potentially traverse the whole cgroup tree and
decrease atomic page counters.
I'm not sure I understand the benefits we get from this change which
do justify the slowdown on the cleanup path.
Thanks!
I was notified of a lockdep splat that this patch may help to prevent.
Would you mind to test this patch:
https://www.spinics.net/lists/cgroups/msg31244.html ?
It should address this dependency.
Thanks for the pointer. I believe that your patch should be able to
address this circular locking dependency.
Feel free to add my
Reviewed-by: Waiman Long <longman@xxxxxxxxxx>
BTW, have you posted it to lkml? If not, would you mind doing so?
Not yet.
I was waiting for Alexander to confirm that it resolves the originally reported
issue. I just pinged him, will wait for tomorrow and post the patch in any case.
Thanks!
I see. This is not a problem that is easily reproducible. You need to
hit the right timing for the lockdep splat to appear.
Regards,
Longman
