From nobody Mon Apr 6 13:29:22 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B48333D4134 for ; Thu, 19 Mar 2026 13:00:25 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773925225; cv=none; b=npcrGRbO3hI4qA5j+U06DqftVWN53S8/uP2YbNNYSaAXH73adHSyfORKuMkQg85pqWkwPj09G//jNJRRcQxXwLEfjaxH730av6x6NDLQ+zf6zwg8BjJfqxUArEJ6ysYOTJj74z3XBTj3Sd2VTzr68ZJiAGRVHtYTN5S/U4QRMF4= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773925225; c=relaxed/simple; bh=4y+/KaN7o4uNUZ28b17IguSawucIT3PNfW8u1Hj6ja4=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=XhEVA+dtEfGx8dEY98ByMlWy3PyTxHnQA+Mfq9PnYFtsduaFIOLq6Q2jSYaGqVKi7XNeqwreH74f+qKTCLnrFVVmPIJqOQP1eVsFrcHXXEljM+CqocIm4rnLZDyI/m3d0uUE+ut43LV0hqypSg+xQTe75Wcb+ZScxDVYdZgCX2Q= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=H6ekloSc; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="H6ekloSc" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E231BC19424; Thu, 19 Mar 2026 13:00:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1773925225; bh=4y+/KaN7o4uNUZ28b17IguSawucIT3PNfW8u1Hj6ja4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=H6ekloScPfjc7+S4h2C/Kfoe9ISQzCEiRPG+d3JF+FigoXlec6Fd81nEe8bjTT/rJ 1as6udnZgmK9AqAEYiBm7LjG+KbLDyaHxQVYPO10SGCDBhbsT3l6VGDwzz/P5LxFbT z+TzYOBq+QXc/tV/9vpw4hpjuIeSha/bnlsRzx3plJ5p8eXdQqA1KIyEaQv5OwREuk OQXPUkO411kSJJgJ7FFy6AYN6L0AU+KvqLX/TUkJomPje6/q/ab8gDsH/gJD3KY/8j kP+YZzOYTX3CL1O99luF5/DYAwEY9Cyfzj8kQe1gbLH07tECWfD0aTZTSTak0BQVMq PhWCdNo7IUg8g== From: "Lorenzo Stoakes (Oracle)" To: Andrew Morton Cc: David Hildenbrand , Zi Yan , Baolin Wang , "Liam R . Howlett" , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [PATCH v2 2/9] mm/huge: avoid big else branch in zap_huge_pmd() Date: Thu, 19 Mar 2026 13:00:08 +0000 Message-ID: X-Mailer: git-send-email 2.53.0 In-Reply-To: References: 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" We don't need to have an extra level of indentation, we can simply exit early in the first two branches. Reviewed-by: Baolin Wang Acked-by: Qi Zheng Signed-off-by: Lorenzo Stoakes (Oracle) --- mm/huge_memory.c | 87 +++++++++++++++++++++++++----------------------- 1 file changed, 45 insertions(+), 42 deletions(-) diff --git a/mm/huge_memory.c b/mm/huge_memory.c index f76edfa91e96..4ebe1f19341e 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -2421,8 +2421,10 @@ static inline void zap_deposited_table(struct mm_str= uct *mm, pmd_t *pmd) int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, pmd_t *pmd, unsigned long addr) { - pmd_t orig_pmd; + struct folio *folio =3D NULL; + int flush_needed =3D 1; spinlock_t *ptl; + pmd_t orig_pmd; =20 tlb_change_page_size(tlb, HPAGE_PMD_SIZE); =20 @@ -2443,59 +2445,60 @@ int zap_huge_pmd(struct mmu_gather *tlb, struct vm_= area_struct *vma, if (arch_needs_pgtable_deposit()) zap_deposited_table(tlb->mm, pmd); spin_unlock(ptl); - } else if (is_huge_zero_pmd(orig_pmd)) { + return 1; + } + if (is_huge_zero_pmd(orig_pmd)) { if (!vma_is_dax(vma) || arch_needs_pgtable_deposit()) zap_deposited_table(tlb->mm, pmd); spin_unlock(ptl); - } else { - struct folio *folio =3D NULL; - int flush_needed =3D 1; + return 1; + } =20 - if (pmd_present(orig_pmd)) { - struct page *page =3D pmd_page(orig_pmd); + if (pmd_present(orig_pmd)) { + struct page *page =3D pmd_page(orig_pmd); =20 - folio =3D page_folio(page); - folio_remove_rmap_pmd(folio, page, vma); - WARN_ON_ONCE(folio_mapcount(folio) < 0); - VM_BUG_ON_PAGE(!PageHead(page), page); - } else if (pmd_is_valid_softleaf(orig_pmd)) { - const softleaf_t entry =3D softleaf_from_pmd(orig_pmd); + folio =3D page_folio(page); + folio_remove_rmap_pmd(folio, page, vma); + WARN_ON_ONCE(folio_mapcount(folio) < 0); + VM_BUG_ON_PAGE(!PageHead(page), page); + } else if (pmd_is_valid_softleaf(orig_pmd)) { + const softleaf_t entry =3D softleaf_from_pmd(orig_pmd); =20 - folio =3D softleaf_to_folio(entry); - flush_needed =3D 0; + folio =3D softleaf_to_folio(entry); + flush_needed =3D 0; =20 - if (!thp_migration_supported()) - WARN_ONCE(1, "Non present huge pmd without pmd migration enabled!"); - } + if (!thp_migration_supported()) + WARN_ONCE(1, "Non present huge pmd without pmd migration enabled!"); + } =20 - if (folio_test_anon(folio)) { + if (folio_test_anon(folio)) { + zap_deposited_table(tlb->mm, pmd); + add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR); + } else { + if (arch_needs_pgtable_deposit()) zap_deposited_table(tlb->mm, pmd); - add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR); - } else { - if (arch_needs_pgtable_deposit()) - zap_deposited_table(tlb->mm, pmd); - add_mm_counter(tlb->mm, mm_counter_file(folio), - -HPAGE_PMD_NR); - - /* - * Use flush_needed to indicate whether the PMD entry - * is present, instead of checking pmd_present() again. - */ - if (flush_needed && pmd_young(orig_pmd) && - likely(vma_has_recency(vma))) - folio_mark_accessed(folio); - } + add_mm_counter(tlb->mm, mm_counter_file(folio), + -HPAGE_PMD_NR); =20 - if (folio_is_device_private(folio)) { - folio_remove_rmap_pmd(folio, &folio->page, vma); - WARN_ON_ONCE(folio_mapcount(folio) < 0); - folio_put(folio); - } + /* + * Use flush_needed to indicate whether the PMD entry + * is present, instead of checking pmd_present() again. + */ + if (flush_needed && pmd_young(orig_pmd) && + likely(vma_has_recency(vma))) + folio_mark_accessed(folio); + } =20 - spin_unlock(ptl); - if (flush_needed) - tlb_remove_page_size(tlb, &folio->page, HPAGE_PMD_SIZE); + if (folio_is_device_private(folio)) { + folio_remove_rmap_pmd(folio, &folio->page, vma); + WARN_ON_ONCE(folio_mapcount(folio) < 0); + folio_put(folio); } + + spin_unlock(ptl); + if (flush_needed) + tlb_remove_page_size(tlb, &folio->page, HPAGE_PMD_SIZE); + return 1; } =20 --=20 2.53.0