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Wed, 02 Jul 2025 01:59:01 -0400 X-MC-Unique: rDf9V_ijOHOWfnRk4VAVBg-1 X-Mimecast-MFC-AGG-ID: rDf9V_ijOHOWfnRk4VAVBg_1751435937 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-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 07C69195FD30; Wed, 2 Jul 2025 05:58:56 +0000 (UTC) Received: from h1.redhat.com (unknown [10.22.88.112]) by mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id CD3581800287; Wed, 2 Jul 2025 05:58:39 +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 Subject: [PATCH v8 02/15] introduce khugepaged_collapse_single_pmd to unify khugepaged and madvise_collapse Date: Tue, 1 Jul 2025 23:57:29 -0600 Message-ID: <20250702055742.102808-3-npache@redhat.com> In-Reply-To: <20250702055742.102808-1-npache@redhat.com> References: <20250702055742.102808-1-npache@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.93 X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: C2D6D40006 X-Stat-Signature: 1rwxane9mqzembeuybiq5i5up34ubfjo X-Rspam-User: X-HE-Tag: 1751435946-627939 X-HE-Meta: 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 7QthO5uV a1qE5v02xnW0wOsO/2VftGSrhn69goVS46u5ujWovTiZqxVW9rMSGLMICkNHLXekQp42Pf6e3MydStgGLZGhNdJ7eNRITxRh4v5hcFgZVzdpVvFPgas9sCWwMo5//3C6HunAIBm3QbRI/4oDuMQ/dagMsMAJ+ZN3/hSXEmtcEzQ0Jaertp1OFnoEyfMImyCEERH8iXM8AMqh4IgpNh2bB20TM/CUzqPgdBXqQ71OBxmz3yFEIcZeZroJ/jJvYG11r9t81kSZs2F2qXNX+/yXByahk1m2nO4+s01wjWN7ZjtFh5QLQbvIlYUIBQY5SkP1QDelRcSp2qcXg+VnJlHT3wWCyPBJ6maZZ41DgFTL4KT9AUlzKZGlvIgc/8VNJdxAyQ415OepKvYivs4paSj6KT+OOEqVM22536a7CxMnbpm6dWZ48nYC9q8njQt0DkhiiOIpM4sCTPCRjzZ97h7RQIYkK573gR8lTVLH4 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 khugepaged_collapse_single_pmd to increase code reuse and create an entry point these two users. Refactor madvise_collapse and khugepaged_scan_mm_slot to use the new khugepaged_collapse_single_pmd function. This introduces a minor behavioral change that is most likely an undiscovered bug. The current implementation of khugepaged tests khugepaged_test_exit_or_disable before calling khugepaged_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 Signed-off-by: Nico Pache --- mm/khugepaged.c | 95 +++++++++++++++++++++++++------------------------ 1 file changed, 49 insertions(+), 46 deletions(-) diff --git a/mm/khugepaged.c b/mm/khugepaged.c index f27fe7ca9b86..bf69e81a3d82 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -2354,6 +2354,50 @@ static int khugepaged_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 khugepaged_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 (IS_ENABLED(CONFIG_SHMEM) && !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 = khugepaged_scan_file(mm, addr, file, pgoff, cc); + fput(file); + if (result == SCAN_PTE_MAPPED_HUGEPAGE) { + mmap_read_lock(mm); + *mmap_locked = true; + if (khugepaged_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 = khugepaged_scan_pmd(mm, vma, addr, mmap_locked, cc); + } + if (cc->is_khugepaged && result == SCAN_SUCCEED) + ++khugepaged_pages_collapsed; +end: + return result; +} + static unsigned int khugepaged_scan_mm_slot(unsigned int pages, int *result, struct collapse_control *cc) __releases(&khugepaged_mm_lock) @@ -2428,34 +2472,9 @@ static unsigned int khugepaged_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 = hpage_collapse_scan_file(mm, - khugepaged_scan.address, file, pgoff, cc); - fput(file); - if (*result == SCAN_PTE_MAPPED_HUGEPAGE) { - mmap_read_lock(mm); - if (hpage_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 = hpage_collapse_scan_pmd(mm, vma, - khugepaged_scan.address, &mmap_locked, cc); - } - - if (*result == SCAN_SUCCEED) - ++khugepaged_pages_collapsed; + *result = khugepaged_collapse_single_pmd(khugepaged_scan.address, + vma, &mmap_locked, cc); /* move to next address */ khugepaged_scan.address += HPAGE_PMD_SIZE; progress += HPAGE_PMD_NR; @@ -2772,35 +2791,19 @@ 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 = hpage_collapse_scan_file(mm, addr, file, pgoff, - cc); - fput(file); - } else { - result = hpage_collapse_scan_pmd(mm, vma, addr, - &mmap_locked, cc); - } + result = khugepaged_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: -- 2.49.0