From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 B5E073F482E; Mon, 17 Aug 2026 11:34:57 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786966498; cv=none; b=JpgUwKwOutNKR9tht7Aj6L1PhvLM3qHh9IGtWhAFGrXZkqjbRO+WiLypvnbNV0RGRl3G0CWDmv+dQhxEjDhqtF/ziX9ciDcRSf3FI7NLGLJPZ0vjnH5yNnqy7oCzn1c4yelJeg6X2Ge1tBpGSfgocM8VWjTByWCBtBpNaBbPP6U= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786966498; c=relaxed/simple; bh=YIH1uv2a3XLeIR8X6C7b6ayC/5syT6hgSQyhNxGlbYA=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=jc1OlsqXWTdd5evWvdvhkY30GCKaqv68kEilD9L2UQpgqMilGxrrI+Hv8b58Z69vlx6gtQ2ccSsgv54mtoXrzrOUHB0DHSM2zQc66uDfZH5SMVDJdBkBLZ2FeTcCWH9Mm/7H8RzZae9EAg3jpJMtGyUw4Ca+D4mHgv4qP+e1X1s= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=JNfLwRIf; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="JNfLwRIf" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A91351F000E9; Mon, 17 Aug 2026 11:34:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1786966497; bh=ZhUYJ0ZuwJek6vTA3gaMgg4QsB61Vmg04/nAHXi8Jj8=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=JNfLwRIfVaBYgaBoNkym1UWIbh/mCvBOZXQeFxobpoFb8TQKZ0rD4diFy6IjGtjih 0J77bz+08aLdAQ5M47GBPHjs+f92By9fcMZ+cL2UMsSpCMGX7ECHS0jk5d/5B8ZBvS BvkJHFcD3cSbDvCtwTgsJPH0VZdyTAPz8AxPrm9D26CAVuRvA65Sj9TzEHSD6ev593 5+E5Wo49JnNuLKPTNHEnfdGXYSJX7Jla3ORwcMjQephwZOSvosdrmUO7U6QASJEi4O WxNZ3xdQPB8m+unAI8PesxXM0OpACbxw/HaSRbL/DwVJnz4GsFyENQ2xCM1Kdvmmzj bai02Jy5m6VrA== Date: Mon, 17 Aug 2026 12:34:37 +0100 From: "Lorenzo Stoakes (ARM)" To: "Nico Pache (Red Hat)" Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, Andrew Morton , David Hildenbrand , Zi Yan , Baolin Wang , "Liam R. Howlett" , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , Usama Arif , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Jonathan Corbet , Shuah Khan Subject: Re: [PATCH v4 3/7] mm/khugepaged: introduce a count_collapse_event() helper Message-ID: References: <20260811-khugepaged_pte_refactor-v4-0-ddac39d61c4a@linux.dev> <20260811-khugepaged_pte_refactor-v4-3-ddac39d61c4a@linux.dev> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260811-khugepaged_pte_refactor-v4-3-ddac39d61c4a@linux.dev> On Tue, Aug 11, 2026 at 06:48:35AM -0600, Nico Pache (Red Hat) wrote: > Provide a simple helper function to help reduce a often used, and > duplicate pattern across the khugepaged code. > > When collapsing to a PMD we need to record a vm_event and the mTHP_stat > event. When doing mTHP collapse we only update the mTHP stat. > > Reviewed-by: Baolin Wang > Acked-by: David Hildenbrand (Arm) > Acked-by: Usama Arif > Signed-off-by: Nico Pache (Red Hat) LGTM so: Reviewed-by: Lorenzo Stoakes (ARM) > --- > mm/khugepaged.c | 42 +++++++++++++++++++++--------------------- > 1 file changed, 21 insertions(+), 21 deletions(-) > > diff --git a/mm/khugepaged.c b/mm/khugepaged.c > index 8babd4c97db6..cae510aa2914 100644 > --- a/mm/khugepaged.c > +++ b/mm/khugepaged.c > @@ -688,6 +688,14 @@ static inline bool folio_pte_referenced(struct folio *folio, > return pte_young(pteval) || mmu_notifier_test_young(vma->vm_mm, addr); > } > > +static void count_collapse_event(unsigned int order, enum vm_event_item vm_event, > + enum mthp_stat_item mthp_event) Add a comment! Lol no only joking ;) > +{ > + if (is_pmd_order(order)) > + count_vm_event(vm_event); > + count_mthp_stat(order, mthp_event); > +} > + > static enum scan_result __collapse_huge_page_isolate(struct vm_area_struct *vma, > unsigned long start_addr, pte_t *pte, struct collapse_control *cc, > unsigned int order, struct list_head *compound_pagelist) > @@ -708,9 +716,8 @@ static enum scan_result __collapse_huge_page_isolate(struct vm_area_struct *vma, > if (pte_none_or_zero(pteval)) { > if (++none_or_zero > max_ptes_none) { > result = SCAN_EXCEED_NONE_PTE; > - if (is_pmd_order(order)) > - count_vm_event(THP_SCAN_EXCEED_NONE_PTE); > - count_mthp_stat(order, MTHP_STAT_COLLAPSE_EXCEED_NONE); > + count_collapse_event(order, THP_SCAN_EXCEED_NONE_PTE, > + MTHP_STAT_COLLAPSE_EXCEED_NONE); > goto out; > } > continue; > @@ -752,9 +759,8 @@ static enum scan_result __collapse_huge_page_isolate(struct vm_area_struct *vma, > */ > if (++shared > max_ptes_shared) { > result = SCAN_EXCEED_SHARED_PTE; > - if (is_pmd_order(order)) > - count_vm_event(THP_SCAN_EXCEED_SHARED_PTE); > - count_mthp_stat(order, MTHP_STAT_COLLAPSE_EXCEED_SHARED); > + count_collapse_event(order, THP_SCAN_EXCEED_SHARED_PTE, > + MTHP_STAT_COLLAPSE_EXCEED_SHARED); > goto out; > } > } > @@ -1264,15 +1270,12 @@ static enum scan_result alloc_charge_folio(struct folio **foliop, struct mm_stru > folio = __folio_alloc(gfp, order, node, &cc->alloc_nmask); > if (!folio) { > *foliop = NULL; > - if (is_pmd_order(order)) > - count_vm_event(THP_COLLAPSE_ALLOC_FAILED); > - count_mthp_stat(order, MTHP_STAT_COLLAPSE_ALLOC_FAILED); > + count_collapse_event(order, THP_COLLAPSE_ALLOC_FAILED, > + MTHP_STAT_COLLAPSE_ALLOC_FAILED); > return SCAN_ALLOC_HUGE_PAGE_FAIL; > } > > - if (is_pmd_order(order)) > - count_vm_event(THP_COLLAPSE_ALLOC); > - count_mthp_stat(order, MTHP_STAT_COLLAPSE_ALLOC); > + count_collapse_event(order, THP_COLLAPSE_ALLOC, MTHP_STAT_COLLAPSE_ALLOC); > > if (unlikely(mem_cgroup_charge(folio, mm, gfp))) { > folio_put(folio); > @@ -1662,9 +1665,8 @@ static enum scan_result collapse_scan_pmd(struct mm_struct *mm, > if (pte_none_or_zero(pteval)) { > if (++none_or_zero > max_ptes_none) { > result = SCAN_EXCEED_NONE_PTE; > - count_vm_event(THP_SCAN_EXCEED_NONE_PTE); > - count_mthp_stat(HPAGE_PMD_ORDER, > - MTHP_STAT_COLLAPSE_EXCEED_NONE); > + count_collapse_event(HPAGE_PMD_ORDER, THP_SCAN_EXCEED_NONE_PTE, > + MTHP_STAT_COLLAPSE_EXCEED_NONE); > goto out_unmap; > } > continue; > @@ -1672,9 +1674,8 @@ static enum scan_result collapse_scan_pmd(struct mm_struct *mm, > if (!pte_present(pteval)) { > if (++unmapped > max_ptes_swap) { > result = SCAN_EXCEED_SWAP_PTE; > - count_vm_event(THP_SCAN_EXCEED_SWAP_PTE); > - count_mthp_stat(HPAGE_PMD_ORDER, > - MTHP_STAT_COLLAPSE_EXCEED_SWAP); > + count_collapse_event(HPAGE_PMD_ORDER, THP_SCAN_EXCEED_SWAP_PTE, > + MTHP_STAT_COLLAPSE_EXCEED_SWAP); > goto out_unmap; > } > /* > @@ -1731,9 +1732,8 @@ static enum scan_result collapse_scan_pmd(struct mm_struct *mm, > if (folio_maybe_mapped_shared(folio)) { > if (++shared > max_ptes_shared) { > result = SCAN_EXCEED_SHARED_PTE; > - count_vm_event(THP_SCAN_EXCEED_SHARED_PTE); > - count_mthp_stat(HPAGE_PMD_ORDER, > - MTHP_STAT_COLLAPSE_EXCEED_SHARED); > + count_collapse_event(HPAGE_PMD_ORDER, THP_SCAN_EXCEED_SHARED_PTE, > + MTHP_STAT_COLLAPSE_EXCEED_SHARED); > goto out_unmap; > } > } > > -- > 2.55.0 > -- Cheers, Lorenzo