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 /3RxW01c Z+nGmFNRcdFkhYzuPDAKPMfCgRk11AMShdxYQ3szXFHtlYMjrfAFo2aDD4RIwyH85eqYDlpUFGkDDaJWTtf55oTNPTw+8tkwEQzGoibJeoZFieTZPQ2qfOo1BQGSVPFnZDSiF8E+53Ph8LDxIp3+5yXz66yGN14fCz6kQ91slbT6WyNQu0CygQKXdHBx1en5tWFM6SHmRhhZrMk6AsnfOv2knOArwcIc2JaluTsgzwLcWSNWY96nnxoxqFuOP5aEGnNRGsb04oHWpFp40e0s591YNbOSJJQvYGFOsuLNvTc+LIjbBtho8vm/sj0OC9YekFOsCAAzy7ifondcwaUH3bXQYzO9Qmma0b71yk6UQ5OE+8m/ACFvV11VnQP1qvPfBEIL+7y7DFPbN/Xqv+RPBQJV7UU53KUsVXXzWq4en1PwgvEtgZvIYF2rKCmXYrvxazrKhcyAvoVDAYcZS9Ej1PayYVw== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 25 Sep 2025, at 15:35, David Hildenbrand wrote: > On 25.09.25 08:11, Qi Zheng wrote: >> Hi David, > > Hi :) > > [...] > >>>> +++ b/include/linux/mmzone.h >>>> @@ -1346,6 +1346,7 @@ struct deferred_split { >>>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 spinlock_t split_queue_lock; >>>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 struct list_head split_queue; >>>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 unsigned long split_queue_len; >>>> +=C2=A0=C2=A0=C2=A0 bool is_dying; >>> >>> It's a bit weird to query whether the "struct deferred_split" is dying. >>> Shouldn't this be a memcg property? (and in particular, not exist for >> >> There is indeed a CSS_DYING flag. But we must modify 'is_dying' under >> the protection of the split_queue_lock, otherwise the folio may be added >> back to the deferred_split of child memcg. > > Is there no way to reuse the existing mechanisms, and find a way to have = the shrinker / queue locking sync against that? > > There is also the offline_css() function where we clear CSS_ONLINE. But i= t happens after calling ss->css_offline(css); I see CSS_DYING will be set by kill_css() before offline_css() is called. Probably the code can check CSS_DYING instead. > > Being able to query "is the memcg going offline" and having a way to sync= against that would be probably cleanest. So basically, something like: 1. at folio_split_queue_lock*() time, get folio=E2=80=99s memcg or its parent memcg until there is no CSS_DYING set or CSS_ONLINE is set. 2. return the associated deferred_split_queue. > > I'll let all the memcg people comment on how that could be done best. > >> >>> the pglist_data part where it might not make sense at all?). >> >> Maybe: >> >> #ifdef CONFIG_MEMCG >> bool is_dying; >> #endif >> > > Still doesn't quite look like it would belong here :( > > Also, is "dying" really the right terminology? It's more like "going offl= ine"? > > But then, the queue is not going offline, the memcg is ... > > --=20 > Cheers > > David / dhildenb Best Regards, Yan, Zi