From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-ed1-f52.google.com (mail-ed1-f52.google.com [209.85.208.52]) (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 51E1828000F for ; Sat, 8 Nov 2025 01:44:29 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.208.52 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762566271; cv=none; b=a1FxNdZoFeVDS2gP/WEh8gI6sRWhrGFMGCMce3n93na5qYBnCZMo1CZ4PyQDtG4ReiQYYl8sNMlZG62TIeFVrK39+/kjqzHHavpQO5Cjd5KFLqrP7mcWpLtWwy3fn8FP9817ovqRipABQCsNdT5wULGk48mg+xUHWNJDQNZih9o= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762566271; c=relaxed/simple; bh=0guTedJhI823d1qbNjlNhspFMNH29JHvsn94D1G+3oU=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=mobUX/UFy6une3l7G47bjpuG+DhhOSEazxXwFBEQDC1JJ8BIY/MFOHMshQ90ij6NkTsRxMFdw9h60a+MAdgs1nKmOO4QdCfY1gJDI3nSB11u0uzISCZLxDS2DkfJicaE2pS0PI+2mCUPIYQUJjkOhmAPG+3sjPI7HtSDlm1w4ao= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=bp0nCpkk; arc=none smtp.client-ip=209.85.208.52 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="bp0nCpkk" Received: by mail-ed1-f52.google.com with SMTP id 4fb4d7f45d1cf-640c48b3b90so2206483a12.0 for ; Fri, 07 Nov 2025 17:44:29 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1762566268; x=1763171068; darn=vger.kernel.org; h=user-agent:in-reply-to:content-disposition:mime-version:references :reply-to:message-id:subject:cc:to:from:date:from:to:cc:subject:date :message-id:reply-to; bh=uHGSN17jZMfxWvKzapCEmQ8MEhEu5sMdAfX0dihLnKo=; b=bp0nCpkkMaYh7dUHEUS16T/pw83qBP84bj5zTMZT9adHyfSJK2L4EM7t8OVYzkQSwT igVn8PqTPGwXEXia//a5B4T7gUqULyIjvDt4U+CKhclQHo4na0H9hK4+Hq9IZsbwbwkS xaoTCpLkhSM2BMRmlPXfBnCog45FwB5oiqM+FYylAqiTIvDfdajgCxPpU8X4PC9xuDWY ZIGlLzi5AHUwp/1Ecbq9IKHC+WJv5b2UBQBTB9UEho5FBrn9gagur806LOTZRXK7PT3Z YpVSXrTxr8DZc4fVOl+Bm2ywU+VgrMTgRNnnJ4ylmobXYADqxWtB3qDHXYPr9Rbjp3yI rdnQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1762566268; x=1763171068; h=user-agent:in-reply-to:content-disposition:mime-version:references :reply-to:message-id:subject:cc:to:from:date:x-gm-gg :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=uHGSN17jZMfxWvKzapCEmQ8MEhEu5sMdAfX0dihLnKo=; b=mBCTKT3R1yqZeKdfoXZAAKDgRdaNyC0EF7ptw6NMgVLizzshyyyN4A8pimWCg8ZyaV dKaB8RlnyNsXXngAIGUiC3cjv4A/V1WEvpX2mzba9YOHPUKKc+USN/3+9DmIUrlD0PEC BEZ3zH+mqESKH/KgEvgI0ab9RJJ2AB+zjjmTD39dwSkKotAC4nnyAIigEw9ZXRuijaFj 4aXAFOkUfX3nRFKQvMzlN0us4csfZ/GXclnPhBthkREUwDudPbu8aaznjz/IrlUVAxMq DluardkyDpzVcfaa2IHx/wmLmU9KJ6GORjRf20M8U/ruFEOU4TEXrx//h6MhxCJ+mizO 4Iiw== X-Forwarded-Encrypted: i=1; AJvYcCVCYCRZZyW3y8Ew2HJxBYycpOXXD3I4DHnw7zFadULe2+c1myc/qN2tItnO1wj4vCjcWBIOY/tYNRPJo3zQF7pGWl8=@vger.kernel.org X-Gm-Message-State: AOJu0YyOYYD9pjtROLT+r8vxeh8blpQK10FZu6lRZlD17dZxu7yyE+UL /TgEY3Q4gEzb0VMuZj9l3sELNv9e4VDiT8lzk+PYABREUH9ejx/853mq X-Gm-Gg: ASbGnctEF9SomkhDCNRc3Vnp+HhLVfZTDkkaQrYdOJl+rb3dkcdn8P6EIHxvPl1nHDr JMQ+Fcfnc/T5wBdddHxdhxK5SqXnlrPrHdRoD1ODvP8T/7QJgHKXzroMRbKsd890ugDdo+15fY2 Mv+bnPdXW/2rrNLVkuMRBsHhc57xlbMjXWJidihLtwrU40MvCOpRHUWoHczwB8MXBmlGbk3exnz pwswy0zgp1VxX6wQuncn4c6SS40mG85T/nwKTLBEn3MvRrZjgvIZA8Dz0E3aLtdG4Ef46jJqriv TEpLGqmInYsQnepFADoZP9xX0IlkFng6oIzBcdxst9QWBJ2nih/xKJKEC+buK414eLuO5j5kmPl WyOwsrfgOTTLZmFExLHCbq6jvW1R9Lsp+fgNyFcJeJwCvbratMJ5Odx5GMLQw+IVNAvLRwXfDIh +vqmDPXaFOZA== X-Google-Smtp-Source: AGHT+IHhwXLk7xWiTIAmHwBxke3RFdw4hY5rd+dV3nC2lXtWeKTLFKd/7oouP3Wzzn4re7c2VoD8dQ== X-Received: by 2002:a05:6402:524f:b0:640:c454:e9 with SMTP id 4fb4d7f45d1cf-6415e5cccfbmr868352a12.4.1762566267419; Fri, 07 Nov 2025 17:44:27 -0800 (PST) Received: from localhost ([185.92.221.13]) by smtp.gmail.com with ESMTPSA id 4fb4d7f45d1cf-6411f813eb6sm5471242a12.14.2025.11.07.17.44.26 (version=TLS1_2 cipher=ECDHE-ECDSA-CHACHA20-POLY1305 bits=256/256); Fri, 07 Nov 2025 17:44:27 -0800 (PST) Date: Sat, 8 Nov 2025 01:44:26 +0000 From: Wei Yang To: Nico Pache Cc: linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-mm@kvack.org, linux-doc@vger.kernel.org, david@redhat.com, ziy@nvidia.com, baolin.wang@linux.alibaba.com, lorenzo.stoakes@oracle.com, Liam.Howlett@oracle.com, ryan.roberts@arm.com, dev.jain@arm.com, corbet@lwn.net, rostedt@goodmis.org, mhiramat@kernel.org, mathieu.desnoyers@efficios.com, akpm@linux-foundation.org, baohua@kernel.org, willy@infradead.org, peterx@redhat.com, wangkefeng.wang@huawei.com, usamaarif642@gmail.com, sunnanyong@huawei.com, vishal.moola@gmail.com, thomas.hellstrom@linux.intel.com, yang@os.amperecomputing.com, kas@kernel.org, aarcange@redhat.com, raquini@redhat.com, anshuman.khandual@arm.com, catalin.marinas@arm.com, tiwai@suse.de, will@kernel.org, dave.hansen@linux.intel.com, jack@suse.cz, cl@gentwo.org, jglisse@google.com, surenb@google.com, zokeefe@google.com, hannes@cmpxchg.org, rientjes@google.com, mhocko@suse.com, rdunlap@infradead.org, hughd@google.com, richard.weiyang@gmail.com, lance.yang@linux.dev, vbabka@suse.cz, rppt@kernel.org, jannh@google.com, pfalcato@suse.de Subject: Re: [PATCH v12 mm-new 02/15] introduce collapse_single_pmd to unify khugepaged and madvise_collapse Message-ID: <20251108014426.5lwchfsvgkoo72fc@master> Reply-To: Wei Yang References: <20251022183717.70829-1-npache@redhat.com> <20251022183717.70829-3-npache@redhat.com> Precedence: bulk X-Mailing-List: linux-trace-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: <20251022183717.70829-3-npache@redhat.com> User-Agent: NeoMutt/20170113 (1.7.2) On Wed, Oct 22, 2025 at 12:37:04PM -0600, Nico Pache wrote: >The khugepaged daemon and madvise_collapse have two different >implementations that do almost the same thing. > >Create collapse_single_pmd to increase code reuse and create an entry >point to these two users. > >Refactor madvise_collapse and collapse_scan_mm_slot to use the new >collapse_single_pmd function. This introduces a minor behavioral change >that is most likely an undiscovered bug. The current implementation of >khugepaged tests collapse_test_exit_or_disable before calling >collapse_pte_mapped_thp, but we weren't doing it in the madvise_collapse >case. By unifying these two callers madvise_collapse now also performs >this check. We also modify the return value to be SCAN_ANY_PROCESS which >properly indicates that this process is no longer valid to operate on. > >We also guard the khugepaged_pages_collapsed variable to ensure its only >incremented for khugepaged. > >Reviewed-by: Baolin Wang >Acked-by: David Hildenbrand >Signed-off-by: Nico Pache Reviewed-by: Wei Yang One nit below. >--- > mm/khugepaged.c | 97 ++++++++++++++++++++++++++----------------------- > 1 file changed, 52 insertions(+), 45 deletions(-) > >diff --git a/mm/khugepaged.c b/mm/khugepaged.c >index 6c4abc7f45cf..36e31d99e507 100644 >--- a/mm/khugepaged.c >+++ b/mm/khugepaged.c >@@ -2370,6 +2370,53 @@ static int collapse_scan_file(struct mm_struct *mm, unsigned long addr, > return result; > } > >+/* >+ * Try to collapse a single PMD starting at a PMD aligned addr, and return >+ * the results. >+ */ >+static int collapse_single_pmd(unsigned long addr, >+ struct vm_area_struct *vma, bool *mmap_locked, >+ struct collapse_control *cc) >+{ >+ struct mm_struct *mm = vma->vm_mm; >+ int result; >+ struct file *file; >+ pgoff_t pgoff; >+ >+ if (vma_is_anonymous(vma)) { >+ result = collapse_scan_pmd(mm, vma, addr, mmap_locked, cc); >+ goto end; >+ } >+ >+ file = get_file(vma->vm_file); >+ pgoff = linear_page_index(vma, addr); >+ >+ mmap_read_unlock(mm); >+ *mmap_locked = false; >+ result = collapse_scan_file(mm, addr, file, pgoff, cc); >+ fput(file); >+ if (result != SCAN_PTE_MAPPED_HUGEPAGE) >+ goto end; >+ >+ mmap_read_lock(mm); >+ *mmap_locked = true; >+ if (collapse_test_exit_or_disable(mm)) { >+ mmap_read_unlock(mm); >+ *mmap_locked = false; >+ return SCAN_ANY_PROCESS; >+ } >+ result = collapse_pte_mapped_thp(mm, addr, !cc->is_khugepaged); >+ if (result == SCAN_PMD_MAPPED) >+ result = SCAN_SUCCEED; >+ mmap_read_unlock(mm); >+ *mmap_locked = false; For all cases, we would set mmap_locked to false. Not sure it bother to adjust it. -- Wei Yang Help you, Help me