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Peter Anvin" , Andrew Morton , Dave Chinner , Qi Zheng , Roman Gushchin , Muchun Song , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Valentin Schneider , K Prateek Nayak , Uladzislau Rezki , David Hildenbrand , Lorenzo Stoakes , "Liam R . Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Kees Cook , Sebastian Andrzej Siewior , Clark Williams , suleiman@google.com, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, linux-rt-devel@lists.linux.dev Subject: Re: [RFC 06/10] Reclaim memory from blocked kernel stacks Message-ID: <20260829084328.GO788244@noisy.programming.kicks-ass.net> References: <20260827232948.2520558-1-stevensd@google.com> <20260827232948.2520558-7-stevensd@google.com> <20260828120408.GN687043@noisy.programming.kicks-ass.net> <20260829083929.GZ776954@noisy.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260829083929.GZ776954@noisy.programming.kicks-ass.net> X-Stat-Signature: fgxzs796h4ajz7xk3qzgoo3yi4t94b5q X-Rspamd-Queue-Id: 76BA8140007 X-Rspamd-Server: rspam02 X-Rspam-User: X-HE-Tag: 1787993022-762268 X-HE-Meta: U2FsdGVkX1+n3GoBUEwV10npzHp7zDzW/CUgKErK/5Cj0arMKrUA066CJXgwVNRdE/rs1BmxcXNzHTADyy+L9K3LKmtKi3YkYTrtgcbuvoft0ISldFZXIlxYkpmgP5RnTHc4Qqp47tMyuS0Iv3KCOIG0RGoreiiwhrfKA7iQz2f5i9HCoQVwqxe1489mnvXiW/oc/iWFd2jKNJNb8hS7O/p2XCTq/29zBA9Er+plqs+FYFTtsUeCVjinLJSZw8AdhPNsPYF6GSfN47uSyBUotxdkJJdFi63BhgixrnJld9O/ya/BI8INfomVBzhVOmYAAhnTvR5s/aVw2cAlxb8TZmP+1p+gyTPOOcUH4ohTyB/kIX98l91Y3uuRuIBQ54gRtAUxKWWfdo5I8lYcJUy6LbdHMdZxg5Cuy6TPJbZ74H4F/fL74MXjtksmuF/nekqlA/L4O5VQfgWhvCfVDuiVJnBTtDXFDE5wTvdrp80PgYTtN6JcHA7D6lQDDQTWgk/0ofPE6pZFdvyBDie/PFA28FjxdMdRhu/rTHpA4GlkQ0KNJN0XPjQVwEh3TWK2e/LPxau6mV4A5+sO7PTfJNdsfUK2bgN/nai7p3cnzHVK7gViZJmvyzC7exYpTQQgqArOsnaUjkuo9vLG4dneLprD3aqm3A/LcM9+3+QUqCjfPH3Z+scRCCHLajr1U7BBpvZ3wDJw+xGclpMeBLIyrSkNLs88hzeXE+UH88dGcY0gtWTQ477AY8zCLUyYPiWKwV9IQLm3xkmomg1/3bjvv4e1W2Qv3cQyJJlxLt+IXMtpHnIV1qgsJPQxzrpM7kY49ryl/e/OqOvyrdpp10dNaTOa/4d3N70X7NHC7mYiXTghvdDJ1LkiWLW/FvWC0cSI2OWbcFei6I7wDtAB8a9gayKWS7D3WrqtiFzJKSBlq6YYF9Qu2V9gPI5Ctue6N6R7yhBt+BO4YbNfmbXZVHaFRB1 0skbuBmT bvrZVdKmuLxmYVAdXdUTIBNy0dpEH21pyf32zkMn0FCr6gfLfqnd/BQnJPsq5k8rgRK95we+YHw+nvxb4auhePqWIPA7MmIPi1+CoYOKnqsX0+tGh7+JTRCpon3yKdj9osH4dgJ1SWlDbaAnyy0HllyZteSxCu8fRdMRhLz0XsHeiI9ZA7JwugZeqBDyTWuDu6uYARGpXA48B2+kqQfTysiCQWtDO1iGnEBNct6bnMIJeq3Y= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Sat, Aug 29, 2026 at 10:39:29AM +0200, Peter Zijlstra wrote: > > The optimistic fast path for repopulate_stack() could be modified to > > try pulling from a pre-allocated pool of zero'ed pages. That would > > reduce the function to a couple of memcg_kmem_charge_page() calls and > > Afaict memcg_kmem_charge_page() ends up in a local_lock, which is a > spinlock, so that cannot be. Perhaps just don't uncharge them on reclaim, then you don't have to re-charge.