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Received: from banye.tbsite.net(mailfrom:qinyuntan@linux.alibaba.com fp:SMTPD_---0XB027Bp_1789446347 cluster:ay36) by smtp.aliyun-inc.com; Tue, 15 Sep 2026 12:25:48 +0800 From: Qinyun Tan To: akpm@linux-foundation.org Cc: hannes@cmpxchg.org, mhocko@suse.com, roman.gushchin@linux.dev, shakeel.butt@linux.dev, muchun.song@linux.dev, david@kernel.org, ljs@kernel.org, ziy@nvidia.com, baolin.wang@linux.alibaba.com, xlpang@linux.alibaba.com, liam@infradead.org, nico.pache@linux.dev, ryan.roberts@arm.com, dev.jain@arm.com, baohua@kernel.org, lance.yang@linux.dev, usama.arif@linux.dev, vbabka@kernel.org, rppt@kernel.org, surenb@google.com, chris@chrisdown.name, kasong@tencent.com, linux-mm@kvack.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, Qinyun Tan Subject: [PATCH v2 0/1] mm: memcg: don't hand out large folios above memory.high Date: Tue, 15 Sep 2026 12:25:45 +0800 Message-ID: <20260915042546.279410-1-qinyuntan@linux.alibaba.com> X-Mailer: git-send-email 2.43.7 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 6741D1C0002 X-Rspam-User: X-Stat-Signature: 7t5mt1p39en4abdiouo5r85grkg9n9mj X-HE-Tag: 1789446353-492469 X-HE-Meta: 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 T+7ScPz4 Dv0i1OqVDep7Y4wJQ9wsPTW9Mz05EHp3iuLrvEPdCASSEUgVhg0zrGoNJez1+j7zX8T46Yyk3WLVDGfwxGW74RMTNPv5c8Gr4NUtJgYwXH1Iy6sLwHlVb+V1DbygAyZa8Njk/X6TMCHcFSLXGwujqFTYOZxUi38VA8hrhM9L+PZ83KyKkUzxPm1uUnyCUj8XhkrIM1HLvDEbKtSGn3Xo3MBtqbfMpKzZMUzQwZGhuC4l07WkEB3/wn5p1ActjFksntSGwMF+z4Xqq1cOb6Ot2Yn5Mg8slFzJwrQJSemkgWdQQGqE= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: memory.high is enforced at two points after a charge succeeds: on return to userspace, and synchronously in try_charge_memcg() for large overcharges, the latter gated on gfpflags_allow_blocking(). The THP fault paths pass the physical allocation gfp from vma_thp_gfp_mask() to the memcg charge. With the default defrag=madvise (and no MADV_HUGEPAGE), as well as with defrag=defer, that gfp does not allow blocking, so inside a single-syscall populate loop - mlock(), MADV_POPULATE_*, any GUP-driven population - neither enforcement point runs: usage grows from memory.high straight up to memory.max with no reclaim and no penalty sleep, consuming the reaction window that userspace OOM handlers (oomd, Kubernetes) depend on. v1 [1] settled the accrued over-high debt from the fault paths after each non-blocking large folio charge. As Zi Yan pointed out in his review [2], falling back to order-0 above memory.high is the better answer: above high the cgroup is meant to be under heavy reclaim pressure, and the order-0 fallback's charge blocks, so it is throttled synchronously as is. v2 does that instead, and is a single patch now. Qinyun Tan (1): mm: memcg: don't hand out large folios above memory.high include/linux/memcontrol.h | 33 ++++++++++++++++++++++ mm/huge_memory.c | 12 ++++++++ mm/memcontrol.c | 56 ++++++++++++++++++++++++++++++++++++++ mm/memory.c | 7 ++++++ mm/swap_state.c | 16 ++++++++++- 5 files changed, 123 insertions(+), 1 deletion(-) [1] https://lore.kernel.org/lkml/20260904035407.4098627-1-qinyuntan@linux.alibaba.com/ [2] https://lore.kernel.org/lkml/6B46E8DF-679B-4254-A4AF-7B992B0F6460@nvidia.com/ -- 2.43.7