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Tue, 19 Aug 2025 13:43:32 +0000 (UTC) Received: from h1.redhat.com (unknown [10.22.64.137]) by mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 2F56319560AB; Tue, 19 Aug 2025 13:43:12 +0000 (UTC) From: Nico Pache To: linux-mm@kvack.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org Cc: 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, kirill.shutemov@linux.intel.com, 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 Subject: [PATCH v10 02/13] introduce collapse_single_pmd to unify khugepaged and madvise_collapse Date: Tue, 19 Aug 2025 07:41:54 -0600 Message-ID: <20250819134205.622806-3-npache@redhat.com> In-Reply-To: <20250819134205.622806-1-npache@redhat.com> References: <20250819134205.622806-1-npache@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.0 on 10.30.177.12 X-Rspamd-Queue-Id: C9F4740007 X-Stat-Signature: 6z9dj6thge94oxoz86tjyro5beh9w5ex X-Rspam-User: X-Rspamd-Server: rspam06 X-HE-Tag: 1755611022-861895 X-HE-Meta: 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 DzzdtUpZ 62hud+gNpi5kCqY6HadZn5omXHaiauMWvSfVligAqe+31HP/ozDjeiG01NOL21iaJCYpgRHeXr9Wl0e68kxl6LAptrWOAodmuYBwitlc5jEFpmC657faK0Wob4X36767JCc0N61FBP5TWN0LI7htsNEyeeHFTyHIyW+Jcuey/K1uSPHeHgrxlK2ducQ== 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. Reviewed-by: Baolin Wang Acked-by: David Hildenbrand Signed-off-by: Nico Pache --- mm/khugepaged.c | 94 ++++++++++++++++++++++++++----------------------- 1 file changed, 49 insertions(+), 45 deletions(-) diff --git a/mm/khugepaged.c b/mm/khugepaged.c index 0e7bbadf03ee..b7b98aebb670 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -2382,6 +2382,50 @@ 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) +{ + int result = SCAN_FAIL; + struct mm_struct *mm = vma->vm_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; + result = collapse_scan_file(mm, addr, file, pgoff, cc); + fput(file); + if (result == SCAN_PTE_MAPPED_HUGEPAGE) { + mmap_read_lock(mm); + *mmap_locked = true; + if (collapse_test_exit_or_disable(mm)) { + mmap_read_unlock(mm); + *mmap_locked = false; + result = SCAN_ANY_PROCESS; + goto end; + } + 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; + } + } else { + result = collapse_scan_pmd(mm, vma, addr, mmap_locked, cc); + } + if (cc->is_khugepaged && result == SCAN_SUCCEED) + ++khugepaged_pages_collapsed; +end: + return result; +} + static unsigned int collapse_scan_mm_slot(unsigned int pages, int *result, struct collapse_control *cc) __releases(&khugepaged_mm_lock) @@ -2455,34 +2499,9 @@ static unsigned int collapse_scan_mm_slot(unsigned int pages, int *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 = 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; @@ -2799,34 +2818,19 @@ int madvise_collapse(struct vm_area_struct *vma, unsigned long start, mmap_assert_locked(mm); memset(cc->node_load, 0, sizeof(cc->node_load)); nodes_clear(cc->alloc_nmask); - 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; - result = collapse_scan_file(mm, addr, file, pgoff, cc); - fput(file); - } else { - result = collapse_scan_pmd(mm, vma, addr, - &mmap_locked, cc); - } + result = collapse_single_pmd(addr, vma, &mmap_locked, cc); + if (!mmap_locked) *lock_dropped = true; -handle_result: 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 = collapse_pte_mapped_thp(mm, addr, true); - mmap_read_unlock(mm); - goto handle_result; /* Whitelisted set of results where continuing OK */ + case SCAN_PTE_MAPPED_HUGEPAGE: case SCAN_PMD_NULL: case SCAN_PTE_NON_PRESENT: case SCAN_PTE_UFFD_WP: -- 2.50.1