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b=bfAKs4/BGFyCRwCH+PUoi6dKBrSOT1OFhGke+NhSx+WHx0963FCJyFW9CzbIfyul0 hOaELtLEe+yU5C6nghjzsZ6zR6U2DWzOpHJOwEoXQG8AEulvCx1D0ObpkA7/jHr6OT xOoDoUl51JNPx5ccOEpxo2YuH04x9+m4mqhdP81qLxKKadekAhvUgBlb+S9F+OpZ3t JuEH9aIcSI1hdd6QRsU1vhw5eekBF8of1d8GaKhp9DH8rW2x3dWE6pFMjjnoqS1Odr I5qX/9KyfZDx8lDcpND3h+qGgAWlruBELpSZXJNsbe25wY42iV+4pZmnYFSviuU4oQ lUKBIxiULVFUQ== Message-ID: <69c9ac59-4fb2-42fc-a8ae-32f583e47de4@kernel.org> Date: Mon, 5 Jan 2026 17:49:22 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 2/6] mm: khugepaged: refine scan progress number To: Vernon Yang , akpm@linux-foundation.org Cc: lorenzo.stoakes@oracle.com, ziy@nvidia.com, dev.jain@arm.com, baohua@kernel.org, lance.yang@linux.dev, richard.weiyang@gmail.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Vernon Yang References: <20260104054112.4541-1-yanglincheng@kylinos.cn> <20260104054112.4541-3-yanglincheng@kylinos.cn> From: "David Hildenbrand (Red Hat)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam02 X-Stat-Signature: sysp4rmfxikue3d57jqfy8wb4fuytd61 X-Rspam-User: X-Rspamd-Queue-Id: 1402F1A0014 X-HE-Tag: 1767631768-512170 X-HE-Meta: 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 ue1UwdOc OZgqA13uRXu+Hhv0Q+dd0Wov5VowPBLeEPf6ACTnkxPz22bY0n8yoFqzfTRQVhMCRO5ZkljCx6neNNPVa5e5/jXk8jPFuBiuL22Z06RcMukit279b2idtoHPqLSRFdxa9OZauO4rAo36qkWOijO2llXsk+4Y5xanJk5eMweIiRZZi6F/YgrdTQdpjjT4eJFLhB4t3sfeYvOZY6B9PRTt4bf5ULgMloP5BupPZCBMxn1o1fK41Bdbw33pTTuRjsTB+fqChGPJK+UEVGFIv0KOYLyqvWlHDi8TqsU24Aclfr5jFiHWguIgeU19RDMTz6WNRDF0XLmWjLX3/bCFgN34k3AJ+FHBGZwNZ0u4ynmX2hbzLKGlMprHfGRtKipMjtA11qhRb9KEiFQVz6RuMdsz/UU0Kz78atk5qEuIv 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: On 1/4/26 06:41, Vernon Yang wrote: > Currently, each PMD scan always increases `progress` by HPAGE_PMD_NR, > even if only scanning a single page. By counting the actual number of "... a single pmd" ? > pages scanned, the `progress` is tracked accurately. "page table entries / pages scanned" ? > > Signed-off-by: Vernon Yang > --- > mm/khugepaged.c | 31 +++++++++++++++++++++++-------- > 1 file changed, 23 insertions(+), 8 deletions(-) > > diff --git a/mm/khugepaged.c b/mm/khugepaged.c > index 9f99f61689f8..4b124e854e2e 100644 > --- a/mm/khugepaged.c > +++ b/mm/khugepaged.c > @@ -1247,7 +1247,7 @@ static int collapse_huge_page(struct mm_struct *mm, unsigned long address, > static int hpage_collapse_scan_pmd(struct mm_struct *mm, > struct vm_area_struct *vma, > unsigned long start_addr, bool *mmap_locked, > - struct collapse_control *cc) > + int *progress, struct collapse_control *cc) > { > pmd_t *pmd; > pte_t *pte, *_pte; > @@ -1258,23 +1258,28 @@ static int hpage_collapse_scan_pmd(struct mm_struct *mm, > unsigned long addr; > spinlock_t *ptl; > int node = NUMA_NO_NODE, unmapped = 0; > + int _progress = 0; "cur_progress" ? > > VM_BUG_ON(start_addr & ~HPAGE_PMD_MASK); > > result = find_pmd_or_thp_or_none(mm, start_addr, &pmd); > - if (result != SCAN_SUCCEED) > + if (result != SCAN_SUCCEED) { > + _progress = HPAGE_PMD_NR; > goto out; > + } > > memset(cc->node_load, 0, sizeof(cc->node_load)); > nodes_clear(cc->alloc_nmask); > pte = pte_offset_map_lock(mm, pmd, start_addr, &ptl); > if (!pte) { > + _progress = HPAGE_PMD_NR; > result = SCAN_NO_PTE_TABLE; > goto out; > } > > for (addr = start_addr, _pte = pte; _pte < pte + HPAGE_PMD_NR; > _pte++, addr += PAGE_SIZE) { > + _progress++; > pte_t pteval = ptep_get(_pte); > if (pte_none_or_zero(pteval)) { > ++none_or_zero; > @@ -1410,6 +1415,9 @@ static int hpage_collapse_scan_pmd(struct mm_struct *mm, > *mmap_locked = false; > } > out: > + if (progress) > + *progress += _progress; > + > trace_mm_khugepaged_scan_pmd(mm, folio, referenced, > none_or_zero, result, unmapped); > return result; > @@ -2287,7 +2295,7 @@ static int collapse_file(struct mm_struct *mm, unsigned long addr, > > static int hpage_collapse_scan_file(struct mm_struct *mm, unsigned long addr, > struct file *file, pgoff_t start, > - struct collapse_control *cc) > + int *progress, struct collapse_control *cc) > { > struct folio *folio = NULL; > struct address_space *mapping = file->f_mapping; > @@ -2295,6 +2303,7 @@ static int hpage_collapse_scan_file(struct mm_struct *mm, unsigned long addr, > int present, swap; > int node = NUMA_NO_NODE; > int result = SCAN_SUCCEED; > + int _progress = 0; Same here. Not sure if it would be cleaner to just let the parent increment its counter and returning instead the "cur_progress" from the function. -- Cheers David