From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 86C9EE9E31B for ; Thu, 12 Feb 2026 02:24:09 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id E8F926B008A; Wed, 11 Feb 2026 21:24:08 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id E5E366B0092; Wed, 11 Feb 2026 21:24:08 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id D73586B0093; Wed, 11 Feb 2026 21:24:08 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0013.hostedemail.com [216.40.44.13]) by kanga.kvack.org (Postfix) with ESMTP id C86386B008A for ; Wed, 11 Feb 2026 21:24:08 -0500 (EST) Received: from smtpin25.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay07.hostedemail.com (Postfix) with ESMTP id 91002160740 for ; Thu, 12 Feb 2026 02:24:08 +0000 (UTC) X-FDA: 84434209776.25.5B3D708 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by imf26.hostedemail.com (Postfix) with ESMTP id A00CB140002 for ; Thu, 12 Feb 2026 02:24:06 +0000 (UTC) Authentication-Results: imf26.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=JSmlL7Re; spf=pass (imf26.hostedemail.com: domain of npache@redhat.com designates 170.10.133.124 as permitted sender) smtp.mailfrom=npache@redhat.com; dmarc=pass (policy=quarantine) header.from=redhat.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1770863046; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=4xykWdQM5vJ3oEKsCmEuM4BEcEsG5qojr85PS8jMpA0=; b=s9heG7uEAw3BoT3OBMok+YKhNtAOtTj0sIfN9Sh+tvp34KkIJqKA9wivix1Bvf4nM2xZRp U7w6354Tum63ZK9LuYg6qWnR7+CWlOaKrMpQRioi0UUfLl6GMjYzqIn9a3sgIanS+wxyP6 ujgJiNBPoQrAsQGAhv0Y5V0jROr2L9A= ARC-Authentication-Results: i=1; imf26.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=JSmlL7Re; spf=pass (imf26.hostedemail.com: domain of npache@redhat.com designates 170.10.133.124 as permitted sender) smtp.mailfrom=npache@redhat.com; dmarc=pass (policy=quarantine) header.from=redhat.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1770863046; a=rsa-sha256; cv=none; b=6OZibsi8xAm7V3Bs3ehv2VcCDSK3uV7DnXqEFTbXP4MMvn5nzYu8iBhJD8t0XQqz64cqxR rVUxyXqTsCI8bhRVcouBW9g8ADuFEL/4RpZs5QTATTLfDmaBuJJQtDadGqyoUNFI/r9BDn I52vvEq4jAUqdSRH85F0XYDhRLYKthg= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1770863046; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=4xykWdQM5vJ3oEKsCmEuM4BEcEsG5qojr85PS8jMpA0=; b=JSmlL7RetDnydsx3k3XjEHx8JIU/f4g8p57eAYV5HMIMayLec0Y/Z/AQsrdRE7nDvvGwnD 5Q11yDhpeJF/ndSCy1om5XoK8m3dLUFY93+LRa1BDc3hn/W9TF4yKT1ykMItHSLyfP4WJu Q8yja5dPsTxgRQ0KAVsxoKNQJRkkQIQ= Received: from mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-2-E2-xYiB-MhKXMnGm3SvTFQ-1; Wed, 11 Feb 2026 21:24:04 -0500 X-MC-Unique: E2-xYiB-MhKXMnGm3SvTFQ-1 X-Mimecast-MFC-AGG-ID: E2-xYiB-MhKXMnGm3SvTFQ_1770863038 Received: from mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.93]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 0EA7118003FC; Thu, 12 Feb 2026 02:23:58 +0000 (UTC) Received: from h1.redhat.com (unknown [10.22.80.91]) by mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 07CC3180035A; Thu, 12 Feb 2026 02:23:47 +0000 (UTC) From: Nico Pache To: linux-kernel@vger.kernel.org, linux-mm@kvack.org Cc: aarcange@redhat.com, akpm@linux-foundation.org, anshuman.khandual@arm.com, apopple@nvidia.com, baohua@kernel.org, baolin.wang@linux.alibaba.com, byungchul@sk.com, catalin.marinas@arm.com, cl@gentwo.org, corbet@lwn.net, dave.hansen@linux.intel.com, david@kernel.org, dev.jain@arm.com, gourry@gourry.net, hannes@cmpxchg.org, hughd@google.com, jackmanb@google.com, jack@suse.cz, jannh@google.com, jglisse@google.com, joshua.hahnjy@gmail.com, kas@kernel.org, lance.yang@linux.dev, Liam.Howlett@oracle.com, lorenzo.stoakes@oracle.com, mathieu.desnoyers@efficios.com, matthew.brost@intel.com, mhiramat@kernel.org, mhocko@suse.com, npache@redhat.com, peterx@redhat.com, pfalcato@suse.de, rakie.kim@sk.com, raquini@redhat.com, rdunlap@infradead.org, richard.weiyang@gmail.com, rientjes@google.com, rostedt@goodmis.org, rppt@kernel.org, ryan.roberts@arm.com, shivankg@amd.com, sunnanyong@huawei.com, surenb@google.com, thomas.hellstrom@linux.intel.com, tiwai@suse.de, usamaarif642@gmail.com, vbabka@suse.cz, vishal.moola@gmail.com, wangkefeng.wang@huawei.com, will@kernel.org, willy@infradead.org, yang@os.amperecomputing.com, ying.huang@linux.alibaba.com, ziy@nvidia.com, zokeefe@google.com Subject: [PATCH mm-unstable v1 5/5] mm/khugepaged: unify khugepaged and madv_collapse with collapse_single_pmd() Date: Wed, 11 Feb 2026 19:23:29 -0700 Message-ID: <20260212022329.18892-2-npache@redhat.com> In-Reply-To: <20260212022329.18892-1-npache@redhat.com> References: <20260212021835.17755-1-npache@redhat.com> <20260212022329.18892-1-npache@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.93 X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: 0U48OSrxBiaE9M9RvQDWNAjb945emNa9txFuXaTNX1I_1770863038 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: 8bit content-type: text/plain; charset="US-ASCII"; x-default=true X-Stat-Signature: p4o3bdbb8y9g86gyutrtgjum5qfwniyn X-Rspamd-Queue-Id: A00CB140002 X-Rspam-User: X-Rspamd-Server: rspam04 X-HE-Tag: 1770863046-961157 X-HE-Meta: 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 y9WFs4f0 Dry/TR+dH4/pOo3y7g74tRIiiehNsbZXd8velXBZa65RA8h57/LRrgIgrpckd5ElEveWrcHIICpQsngdkHW2DWxJ//1n/Ps1NGAKsPL3v/FPXnbFdKggP6hwxV2vwNVET0p+8jPa4u4Dm+HiQ9QNTIsU4HEK20MTLZ43/iv1VgcKZXsSPfXufFSZgJWn4qH8qOkP+4poHrWiPpa4kWhAc3FF1mJAcUlpqcaV/tRLX9voNTMhrjQNUCpIR93MjZVwFjOGL96y4Dy8PoLjA9jAtXZ6eQbOTOhvmXWkq0oaB3RPBlJnazR+URshjYnsmgioQXlJylrIUpdwBzorOjadzKGFH/aORdNFXqGY7yBd45DshKWXNzKCLA/XrISESRJUSKJQkOOFMNUtKDCxe7hHgNqSWrkOMsXA/8Tz6Qz9HrHEQMVwf0YmEIIwLAJvjn2+sFcbUCqtoUUqz1/2wM3R/3HarwBnOrR8bHaBV 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: 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: Lorenzo Stoakes Signed-off-by: Nico Pache --- mm/khugepaged.c | 121 ++++++++++++++++++++++++++---------------------- 1 file changed, 66 insertions(+), 55 deletions(-) diff --git a/mm/khugepaged.c b/mm/khugepaged.c index fa41480f6948..0839a781bedd 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -2395,6 +2395,62 @@ static enum scan_result collapse_scan_file(struct mm_struct *mm, unsigned long a return result; } +/* + * Try to collapse a single PMD starting at a PMD aligned addr, and return + * the results. + */ +static enum scan_result 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; + enum scan_result 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); + + if (!cc->is_khugepaged && result == SCAN_PAGE_DIRTY_OR_WRITEBACK && + mapping_can_writeback(file->f_mapping)) { + const loff_t lstart = (loff_t)pgoff << PAGE_SHIFT; + const loff_t lend = lstart + HPAGE_PMD_SIZE - 1; + + filemap_write_and_wait_range(file->f_mapping, lstart, lend); + } + 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 = try_collapse_pte_mapped_thp(mm, addr, !cc->is_khugepaged); + if (result == SCAN_PMD_MAPPED) + result = SCAN_SUCCEED; + mmap_read_unlock(mm); + *mmap_locked = false; + +end: + if (cc->is_khugepaged && result == SCAN_SUCCEED) + ++khugepaged_pages_collapsed; + return result; +} + static unsigned int collapse_scan_mm_slot(unsigned int pages, enum scan_result *result, struct collapse_control *cc) __releases(&khugepaged_mm_lock) @@ -2466,34 +2522,9 @@ static unsigned int collapse_scan_mm_slot(unsigned int pages, enum scan_result * VM_BUG_ON(khugepaged_scan.address < hstart || khugepaged_scan.address + HPAGE_PMD_SIZE > hend); - if (!vma_is_anonymous(vma)) { - struct file *file = get_file(vma->vm_file); - pgoff_t pgoff = linear_page_index(vma, - khugepaged_scan.address); - - mmap_read_unlock(mm); - mmap_locked = false; - *result = collapse_scan_file(mm, - khugepaged_scan.address, file, pgoff, cc); - fput(file); - if (*result == SCAN_PTE_MAPPED_HUGEPAGE) { - mmap_read_lock(mm); - if (collapse_test_exit_or_disable(mm)) - goto breakouterloop; - *result = try_collapse_pte_mapped_thp(mm, - khugepaged_scan.address, false); - if (*result == SCAN_PMD_MAPPED) - *result = SCAN_SUCCEED; - mmap_read_unlock(mm); - } - } else { - *result = collapse_scan_pmd(mm, vma, - khugepaged_scan.address, &mmap_locked, cc); - } - - if (*result == SCAN_SUCCEED) - ++khugepaged_pages_collapsed; + *result = collapse_single_pmd(khugepaged_scan.address, + vma, &mmap_locked, cc); /* move to next address */ khugepaged_scan.address += HPAGE_PMD_SIZE; progress += HPAGE_PMD_NR; @@ -2799,6 +2830,7 @@ int madvise_collapse(struct vm_area_struct *vma, unsigned long start, cond_resched(); mmap_read_lock(mm); mmap_locked = true; + *lock_dropped = true; result = hugepage_vma_revalidate(mm, addr, false, &vma, cc); if (result != SCAN_SUCCEED) { @@ -2809,46 +2841,25 @@ int madvise_collapse(struct vm_area_struct *vma, unsigned long start, hend = min(hend, vma->vm_end & HPAGE_PMD_MASK); } mmap_assert_locked(mm); - if (!vma_is_anonymous(vma)) { - struct file *file = get_file(vma->vm_file); - pgoff_t pgoff = linear_page_index(vma, addr); - mmap_read_unlock(mm); - mmap_locked = false; - *lock_dropped = true; - result = collapse_scan_file(mm, addr, file, pgoff, cc); - - if (result == SCAN_PAGE_DIRTY_OR_WRITEBACK && !triggered_wb && - mapping_can_writeback(file->f_mapping)) { - loff_t lstart = (loff_t)pgoff << PAGE_SHIFT; - loff_t lend = lstart + HPAGE_PMD_SIZE - 1; + result = collapse_single_pmd(addr, vma, &mmap_locked, cc); - filemap_write_and_wait_range(file->f_mapping, lstart, lend); - triggered_wb = true; - fput(file); - goto retry; - } - fput(file); - } else { - result = collapse_scan_pmd(mm, vma, addr, &mmap_locked, cc); - } if (!mmap_locked) *lock_dropped = true; -handle_result: + if (result == SCAN_PAGE_DIRTY_OR_WRITEBACK && !triggered_wb) { + triggered_wb = true; + goto retry; + } + switch (result) { case SCAN_SUCCEED: case SCAN_PMD_MAPPED: ++thps; break; - case SCAN_PTE_MAPPED_HUGEPAGE: - BUG_ON(mmap_locked); - mmap_read_lock(mm); - result = try_collapse_pte_mapped_thp(mm, addr, true); - mmap_read_unlock(mm); - goto handle_result; /* Whitelisted set of results where continuing OK */ case SCAN_NO_PTE_TABLE: + case SCAN_PTE_MAPPED_HUGEPAGE: case SCAN_PTE_NON_PRESENT: case SCAN_PTE_UFFD_WP: case SCAN_LACK_REFERENCED_PAGE: -- 2.53.0