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Wed, 01 Jul 2026 04:47:43 -0700 (PDT) Received: from localhost.localdomain ([2607:f130:0:11a::31]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-30ee327cea7sm22518169eec.31.2026.07.01.04.47.39 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Wed, 01 Jul 2026 04:47:42 -0700 (PDT) From: wang lian To: damon@lists.linux.dev, linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org, sj@kernel.org, gutierrez.asier@huawei-partners.com, daichaobing@sangfor.com.cn, lianux.wang@processmission.com, Wang Lian Subject: [PATCH v2 5/5] mm/damon/vaddr: implement DAMOS_SPLIT handler Date: Wed, 1 Jul 2026 19:47:16 +0800 Message-ID: <20260701114716.56503-6-lianux.mm@gmail.com> X-Mailer: git-send-email 2.50.1 In-Reply-To: <20260701114716.56503-1-lianux.mm@gmail.com> References: <20260701114716.56503-1-lianux.mm@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Stat-Signature: hieipf5cox1yoxuxwj34eeh797id7ya8 X-Rspam-User: X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 4D4654000E X-HE-Tag: 1782906464-830221 X-HE-Meta: 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 BjwUAgiO 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: From: Wang Lian Implement the vaddr operations layer handler for DAMOS_SPLIT. For each folio in the target region that is larger than the scheme's target_order, split it via split_folio_to_order(). This supports both anonymous and file-backed (e.g. tmpfs/shmem) folios, covering KVM guest memory backed by THP tmpfs. Signed-off-by: Wang Lian Signed-off-by: Wang Lian --- mm/damon/vaddr.c | 68 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 68 insertions(+) diff --git a/mm/damon/vaddr.c b/mm/damon/vaddr.c index 2a3757c13bf0..3f2061b29ed8 100644 --- a/mm/damon/vaddr.c +++ b/mm/damon/vaddr.c @@ -934,6 +934,71 @@ static unsigned long damos_va_collapse(struct damon_target *target, return applied; } +static unsigned long damos_va_split(struct damon_target *target, + struct damon_region *r, struct damos *s, + unsigned long *sz_filter_passed) +{ + unsigned long addr, end, chunk_sz; + unsigned int target_order = s->target_order; + unsigned long applied = 0; + struct mm_struct *mm; + struct vm_area_struct *vma; + struct folio *folio; + struct folio_walk fw; + + mm = damon_get_mm(target); + if (!mm) + return 0; + + chunk_sz = PAGE_SIZE << HPAGE_PMD_ORDER; + addr = ALIGN_DOWN(r->ar.start, chunk_sz); + end = ALIGN(r->ar.end, chunk_sz); + + while (addr < end) { + mmap_read_lock(mm); + vma = find_vma(mm, addr); + /* + * split_folio_to_order() supports both anon and shmem + * folios, so we accept any VMA that has a folio at @addr. + * This covers important use cases like tmpfs THP-backed + * KVM guest memory where cold and hot pages are bundled + * together in a single PMD THP. + */ + if (!vma || addr < vma->vm_start) + goto unlock; + + folio = folio_walk_start(&fw, vma, addr, 0); + if (!folio) + goto unlock; + + if (folio_order(folio) > target_order) { + if (!folio_trylock(folio)) { + folio_walk_end(&fw, vma); + goto unlock; + } + folio_get(folio); + folio_walk_end(&fw, vma); + + if (!split_folio_to_order(folio, target_order)) + applied += chunk_sz; + + folio_unlock(folio); + folio_put(folio); + } else { + folio_walk_end(&fw, vma); + } + +unlock: + *sz_filter_passed += chunk_sz; + addr += chunk_sz; + mmap_read_unlock(mm); + cond_resched(); + } + + mmput(mm); + return applied; +} + static unsigned long damon_va_apply_scheme(struct damon_ctx *ctx, struct damon_target *t, struct damon_region *r, struct damos *scheme, unsigned long *sz_filter_passed) @@ -967,6 +1032,9 @@ static unsigned long damon_va_apply_scheme(struct damon_ctx *ctx, return damos_va_migrate(t, r, scheme, sz_filter_passed); case DAMOS_STAT: return damos_va_stat(t, r, scheme, sz_filter_passed); + case DAMOS_SPLIT: + return damos_va_split(t, r, scheme, + sz_filter_passed); default: /* * DAMOS actions that are not yet supported by 'vaddr'. -- 2.50.1 (Apple Git-155)