From nobody Sun Feb 8 11:43:44 2026 Received: from mail-pf1-f174.google.com (mail-pf1-f174.google.com [209.85.210.174]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 4C4D71A2C11 for ; Mon, 29 Dec 2025 14:13:15 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.210.174 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767017597; cv=none; b=GttuCNOLj9ftEhXSRZ+bzQ6gwsT2xUWVygxjl0kADD6mJoUtc6GV6g6RtaB0PckLTsDJCnd9jhsRgEjlsgyd5t4oxg9kij1oMrqvKmpoVhgGPk5lB+osBkLARi4AT9FoDFOZtL9a6++JAKlD/lNBB8uCMmlr4VLa+RQ44M+4WVA= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767017597; c=relaxed/simple; bh=lC6GEfxIGK/35lvrPF2qw5D86rHWEQ6C/lNcw05H+jI=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=EU6jJ6y71K01LetsD6GLx0NHBRDSg+OtK8U8gRM4sAmr5ikKvYn5YGHUGWcHixnVaAf3Luo5wNeayfmd7xB2xABe68+qSmkvN4/9MBAoU0UpSuwdDffKjJGma6yYTY55qYr3p1Vc7FDeQbEMkiiO1pzivSA8uCCvFjPFvsteJzE= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=gmail.com; arc=none smtp.client-ip=209.85.210.174 Authentication-Results: smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Received: by mail-pf1-f174.google.com with SMTP id d2e1a72fcca58-7f0da2dfeaeso9724034b3a.1 for ; Mon, 29 Dec 2025 06:13:15 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1767017594; x=1767622394; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-gg:x-gm-message-state:from :to:cc:subject:date:message-id:reply-to; bh=foHDr6tTVVg2N+oq2ubI3TwM6NJy7Osy+6nFP/DCYQ8=; b=Vpct6HKmyS36p3dgHrEwiwNXRw0mddMhIBYiHVCMEqXzkPYWI/UcL2CgcRyg2RH2KT q9s2nTLhLROHCcMJH3pJd6CTXHMVPGmSOAW75lqhmAtF44plAOg/ysiJFEAJ9pvUfsxB XZzNeLVFwqEdGbuX/3ai+R34amtpjBDe7Nfh7KBs9Fomn2lmRzg442hxeMgjhGTE61c7 bdgCw3MI0MKvXvYZjGtelIU+iNPp0bSfHz/LW3JrKBkCK94KQ5ieHl+59NIYEvBqS+Ju GL0QDOAPTpTAsJmJ8wqjI/W3TPpbFYtgCTh5mka8M3o2CJonPCobx4GdXST5Xj1gH8oN kuRA== X-Forwarded-Encrypted: i=1; AJvYcCXy2Z1WL1yQMbzRFhDNcwJiCVbGLTCoRK5URL7gw8CfbcQ4pqTY6DMaz+6s9mLHd1D32783BHv0DRgqmCo=@vger.kernel.org X-Gm-Message-State: AOJu0Yz2Ov+dwH3NtWnl5GlkCgZEBja4xsuvHGCqsKgUsjYhxpWgNO/O JKADoDfnbnNWqOjhfr4/qmsDIUU/IktKe50j5mYe623vHMuWA2nkEcEl X-Gm-Gg: AY/fxX5P9Be+lrzoTYu1dLNd5EEiXT2pxTG+GsUY0cyVQaQmYPONHxEt+zL6H2WLunV nD3xntu1CLIN7zt/e+eiOX00MLjW80oBcwZCMcf35C6vdGS/tQ59GO3n5mqNNCXTAomKDLxg5g6 lflvdu4H9yIaMmd8+DSyt+p0DlZubYFKbpyavvxDgy/ofYxiJ85iPQ8sanpK2mIgIOwTHxJah1M k2QPm8Wyxyd2ntOCHRtSgrA1pHLHeGX/HZchf2aKRbgi4WO1MJXFHLluaLgteOT0ZgZ5TNmWZ6p 9qyuB5TDwRkhKWHjoEo1X3OPXzMXNM6D4y9QtKzXh5xoroewXVJtfBJdWE6qa7iZhEafNNDxZSM dNi/KDLbRnxAOp8FW5Aummk31TevOKNNWrHoOavQGs444OIg3zXpY+MRZLuC0yrmnWAj/MXVCGq iztaled4ShLw4zZZAd3PMh X-Google-Smtp-Source: AGHT+IHjQ5rl02KKPHQhO2WlxDrubU3tUX+Dp23WgXVCA057aOMTV2/+jAKILyQh7BNfdVe+rKUfAQ== X-Received: by 2002:a05:6a21:328a:b0:366:14ac:e1dd with SMTP id adf61e73a8af0-376aaff9943mr29756512637.67.1767017594482; Mon, 29 Dec 2025 06:13:14 -0800 (PST) Received: from EBJ9932692.tcent.cn ([103.88.46.167]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-7ff7a93ab3csm29472636b3a.7.2025.12.29.06.13.05 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Mon, 29 Dec 2025 06:13:14 -0800 (PST) From: Lance Yang To: akpm@linux-foundation.org Cc: will@kernel.org, aneesh.kumar@kernel.org, npiggin@gmail.com, peterz@infradead.org, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com, arnd@arndb.de, david@kernel.org, lorenzo.stoakes@oracle.com, ziy@nvidia.com, baolin.wang@linux.alibaba.com, Liam.Howlett@oracle.com, npache@redhat.com, ryan.roberts@arm.com, dev.jain@arm.com, baohua@kernel.org, ioworker0@gmail.com, shy828301@gmail.com, riel@surriel.com, jannh@google.com, linux-arch@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Lance Yang Subject: [PATCH v1 1/3] mm/tlb: allow architectures to skip redundant TLB sync IPIs Date: Mon, 29 Dec 2025 22:12:43 +0800 Message-ID: <20251229141246.63435-2-lance.yang@linux.dev> X-Mailer: git-send-email 2.49.0 In-Reply-To: <20251229141246.63435-1-lance.yang@linux.dev> References: <20251229141246.63435-1-lance.yang@linux.dev> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Lance Yang When unsharing hugetlb PMD page tables, we currently send two IPIs: one for TLB invalidation, and another to synchronize with concurrent GUP-fast walkers. However, if the TLB flush already reaches all CPUs, the second IPI is redundant. GUP-fast runs with IRQs disabled, so when the TLB flush IPI completes, any concurrent GUP-fast must have finished. Add tlb_table_flush_implies_ipi_broadcast() to let architectures indicate their TLB flush provides full synchronization, enabling the redundant IPI to be skipped. Suggested-by: David Hildenbrand (Red Hat) Signed-off-by: Lance Yang --- include/asm-generic/tlb.h | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/include/asm-generic/tlb.h b/include/asm-generic/tlb.h index 4d679d2a206b..e8d99b5e831f 100644 --- a/include/asm-generic/tlb.h +++ b/include/asm-generic/tlb.h @@ -261,6 +261,20 @@ static inline void tlb_remove_table_sync_one(void) { } =20 #endif /* CONFIG_MMU_GATHER_RCU_TABLE_FREE */ =20 +/* + * Architectures can override if their TLB flush already broadcasts IPIs t= o all + * CPUs when freeing or unsharing page tables. + * + * Return true only when the flush guarantees: + * - IPIs reach all CPUs with potentially stale paging-structure cache ent= ries + * - Synchronization with IRQ-disabled code like GUP-fast + */ +#ifndef tlb_table_flush_implies_ipi_broadcast +static inline bool tlb_table_flush_implies_ipi_broadcast(void) +{ + return false; +} +#endif =20 #ifndef CONFIG_MMU_GATHER_NO_GATHER /* --=20 2.49.0