From nobody Sun Feb 8 11:43:20 2026 Received: from mail-pl1-f171.google.com (mail-pl1-f171.google.com [209.85.214.171]) (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 D8A0031D389 for ; Mon, 29 Dec 2025 14:38:00 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.171 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767019082; cv=none; b=CXxRkgitgcfWANiC/uOKA908BIZDlUH1ziCa+QsqTuarnO+HCW4rqECecOXHABgGOGlw14T8btRlwaTDjOXIFLJ229OCNxMW7b0u7gkkSXpo0HN/yReEO99U1S0oyUt2/cu3LRgK2AqQYRcon42NnOISOVna2hSwL2jgwhs3OMo= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767019082; c=relaxed/simple; bh=lC6GEfxIGK/35lvrPF2qw5D86rHWEQ6C/lNcw05H+jI=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=euIMEKPMRNRhMyNxyCDx3tzMEEtpb9mtqzbTznlYkPTgtftdPTjAxNmI9MD7phNeYEynfOvOTQa0hoHdUI6eFrVkmxAUC3RlqFjq/aRtGMURDM6q9Kody+HKpqHz2dHCXq8z/w6lDO5OBHOdRs9L24nB6+/5OvzpqBhqOQHc4VE= 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=209.85.214.171 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-pl1-f171.google.com with SMTP id d9443c01a7336-2a12ed4d205so79822975ad.0 for ; Mon, 29 Dec 2025 06:38:00 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1767019080; x=1767623880; 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=pNbHB+HwXhTTEoM6MEwywFddrF/RN5OZpeHcxNWp60WfZQbOHsR7oIQHOkknnRk33n 21Ssy0Dl3k+FGIHYBwEnr+G8xTi5K+tS9NmXYo3wkpFPHgrWizK9l3BTKFHUbfQVcP1U arZrOHF/y82BEeLCeRK6VoUdbBkq00p144BEjAtunRaLOxOQ3del590J5EUf3kw6lFXa mp3TBXMFHoZ4BFmudeMsZd4MzFwjTaN7giZwoSD+iz+AtLzcEMNgNWXweelqISgJeX0F 9Zuh0tT/7ongi0y6B/Gh8qp5bTsg3wVXtLEmlU6UjAUj0KUmpXk1jmuQYEWUI9ZNRieb TwBA== X-Forwarded-Encrypted: i=1; AJvYcCUfwh3wpeFALx5A7GNckodmo6XB6DRs87fN1gRz5jVQdfVIhl1PrkRbJ99OlPl/GC+tuR3XOjKEjAXVsx0=@vger.kernel.org X-Gm-Message-State: AOJu0YxYQoP4twILBEd/vsSQjHtg8ZFBYgoa+6EGR9AaWGxP+LcDjo80 F6zbnymjDDI5xI+Xvy5w3vGRUbEtbetwFQDggBPc9b4hub2fvnjLDc2x X-Gm-Gg: AY/fxX500fzt4QZhfKzDM26sIG9/tm51qjA6Iy0jMFnKI2ZjiC+f/QGQY75ub4lZKJ6 lqSJI15Tiipaj89WGfqepXzkLT+ePi7W0HjZzUNv/NdA8wygjq7XHX+WWl9Gh8QbeEsh2YYqJNQ 0k7H7Ob7dpxernViOyI1+/ZL7QHPAUdYZ15p+HfpjkHRlT7UvFP3X00+Kx2jErCzIYeTw8JehCq CKSABBtXXFLsMc1BXf84pJiTbpfWVuemalsgl/6/PifyUoaAmwVaQlc2PxtP/kYgsFdIN5COELf 3l+uGRhllawaQgvqfFOe4HdXkPafeYOh5gG6Q2Zet9UDjukq+B38xStw5lWzY1QAnWWUfNUQ6u/ QmGYI3T16gL34kKfnDCD49Ctm+K5s+M1aRb2DYoapQVdEW4oo/R3SK90FwztAfCKyJKghcWNR3/ S9D67CrWCD/uY5EwPWp2q2JJr8s54atbo= X-Google-Smtp-Source: AGHT+IEV772w153pVl2WpyWEJno3SC8dcLG3m0A8YzC4kscVWxvA6UP//UDe0ihAoD40pu8neBRzLg== X-Received: by 2002:a17:902:f607:b0:295:9e4e:4090 with SMTP id d9443c01a7336-2a2f2a3cea1mr322095945ad.52.1767019079997; Mon, 29 Dec 2025 06:37:59 -0800 (PST) Received: from EBJ9932692.tcent.cn ([45.8.220.167]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2a2f3d7736fsm279669625ad.92.2025.12.29.06.37.50 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Mon, 29 Dec 2025 06:37:58 -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 RESEND v1 1/3] mm/tlb: allow architectures to skip redundant TLB sync IPIs Date: Mon, 29 Dec 2025 22:36:55 +0800 Message-ID: <20251229143657.76968-2-lance.yang@linux.dev> X-Mailer: git-send-email 2.49.0 In-Reply-To: <20251229143657.76968-1-lance.yang@linux.dev> References: <20251229143657.76968-1-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