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Thu, 05 Jun 2025 16:01:14 +0800 From: Baolin Wang To: akpm@linux-foundation.org, hughd@google.com, david@redhat.com Cc: lorenzo.stoakes@oracle.com, Liam.Howlett@oracle.com, npache@redhat.com, ryan.roberts@arm.com, dev.jain@arm.com, ziy@nvidia.com, baolin.wang@linux.alibaba.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [PATCH v2 1/2] mm: huge_memory: disallow hugepages if the system-wide THP sysfs settings are disabled Date: Thu, 5 Jun 2025 16:00:58 +0800 Message-ID: <8eefb0809c598fadaa4a022634fba5689a4f3257.1749109709.git.baolin.wang@linux.alibaba.com> X-Mailer: git-send-email 2.43.5 In-Reply-To: References: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: 302F64000C X-Stat-Signature: p3zhnj8dm99mi6yjih4rsntjqkugjzst X-Rspam-User: X-Rspamd-Server: rspam04 X-HE-Tag: 1749110477-948317 X-HE-Meta: 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 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: The MADV_COLLAPSE will ignore the system-wide Anon THP sysfs settings, which means that even though we have disabled the Anon THP configuration, MADV_COLLAPSE will still attempt to collapse into a Anon THP. This violates the rule we have agreed upon: never means never. Another rule for madvise, referring to David's suggestion: “allowing for collapsing in a VM without VM_HUGEPAGE in the "madvise" mode would be fine". To address this issue, should check whether the Anon THP configuration is disabled in thp_vma_allowable_orders(), even when the TVA_ENFORCE_SYSFS flag is set. In summary, the current strategy is: 1. If always & orders == 0, and madvise & orders == 0, and hugepage_global_enabled() == false (global THP settings are not enabled), it means mTHP of that orders are prohibited from being used, then madvise_collapse() is forbidden for that orders. 2. If always & orders == 0, and madvise & orders == 0, and hugepage_global_enabled() == true (global THP settings are enabled), and inherit & orders == 0, it means mTHP of that orders are still prohibited from being used, thus madvise_collapse() is not allowed for that orders. Reviewed-by: Zi Yan Signed-off-by: Baolin Wang --- include/linux/huge_mm.h | 23 +++++++++++++++++++---- 1 file changed, 19 insertions(+), 4 deletions(-) diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h index 2f190c90192d..199ddc9f04a1 100644 --- a/include/linux/huge_mm.h +++ b/include/linux/huge_mm.h @@ -287,20 +287,35 @@ unsigned long thp_vma_allowable_orders(struct vm_area_struct *vma, unsigned long orders) { /* Optimization to check if required orders are enabled early. */ - if ((tva_flags & TVA_ENFORCE_SYSFS) && vma_is_anonymous(vma)) { - unsigned long mask = READ_ONCE(huge_anon_orders_always); + if (vma_is_anonymous(vma)) { + unsigned long always = READ_ONCE(huge_anon_orders_always); + unsigned long madvise = READ_ONCE(huge_anon_orders_madvise); + unsigned long inherit = READ_ONCE(huge_anon_orders_inherit); + unsigned long mask = always | madvise; + + /* + * If the system-wide THP/mTHP sysfs settings are disabled, + * then we should never allow hugepages. + */ + if (!(mask & orders) && !(hugepage_global_enabled() && (inherit & orders))) + return 0; + + if (!(tva_flags & TVA_ENFORCE_SYSFS)) + goto skip; + mask = always; if (vm_flags & VM_HUGEPAGE) - mask |= READ_ONCE(huge_anon_orders_madvise); + mask |= madvise; if (hugepage_global_always() || ((vm_flags & VM_HUGEPAGE) && hugepage_global_enabled())) - mask |= READ_ONCE(huge_anon_orders_inherit); + mask |= inherit; orders &= mask; if (!orders) return 0; } +skip: return __thp_vma_allowable_orders(vma, vm_flags, tva_flags, orders); } -- 2.43.5