From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A4F6748A2A1; Tue, 1 Sep 2026 17:10:48 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788282649; cv=none; b=FmhT3W2bpkVNbwiVY85wyL24hRLjgOAsXqOMbGzhGN/+kQhtVe3cdKLUa5nG7HUcHR9VvaYQMNFyuRDaHkPH1/9tqC/wj76xQA0pZnEOnotluWVFqsPeol3ADyydqggx2iNlRM+kbYHf3zlPLduWnqMx8mjUHsWI9Fer7WT5NmY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788282649; c=relaxed/simple; bh=bG0SJpd3ZPsk+nxrxdBe/YttPnaTHRCytJn4IXEVL8A=; h=Date:To:From:Subject:Message-Id; b=LWJt7tfSpw3g/4ASWg+54KNj82B0QITOnv8c5vtwBDtD9EFEpRmjjeOg6R7PGI1Yv0h8WjVaovcYIVbBN4Kibm6jKZGTYyZn5YKAcNjrAxm5XgvTR4ZDcIM3KBIsgjtHbDiIGgzrjucb1+SVgl4uwROMytM/h+p5PoKkpiN9iAI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=f4+PUwAv; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="f4+PUwAv" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 425BE1F000E9; Tue, 1 Sep 2026 17:10:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux-foundation.org; s=korg; t=1788282648; bh=BM950h1WUdJGmX6/PQHW24C2sGqKTdv7962Ib7NlWKg=; h=Date:To:From:Subject; b=f4+PUwAvszCXV4Jtzw4Zt8vxZf6Mzyv0eQPbb9FDWQQtmkUzxEZUzH/FMDM2Juq2E swHaou2QzvCSohz0FhkV1iH+8xrzNte3uA2nB3HtRQVuJr0xwWB8YShPUefA7OS4Up cgGqHP2CdCdddMqx5PI0u8pZ122TXqiIK6EkfsdI= Date: Tue, 01 Sep 2026 10:10:47 -0700 To: mm-commits@vger.kernel.org,usamaarif642@gmail.com,stable@vger.kernel.org,sj@kernel.org,akpm@linux-foundation.org From: Andrew Morton Subject: + mm-damon-core-handle-extreme-memory-state-in-get_in_active_mem_bp.patch added to mm-new branch Message-Id: <20260901171048.425BE1F000E9@smtp.kernel.org> Precedence: bulk X-Mailing-List: mm-commits@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The patch titled Subject: mm/damon/core: handle extreme memory state in get_in_active_mem_bp() has been added to the -mm mm-new branch. Its filename is mm-damon-core-handle-extreme-memory-state-in-get_in_active_mem_bp.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-damon-core-handle-extreme-memory-state-in-get_in_active_mem_bp.patch This patch will later appear in the mm-new branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Note, mm-new is a provisional staging ground for work-in-progress patches, and acceptance into mm-new is a notification for others take notice and to finish up reviews. Please do not hesitate to respond to review feedback and post updated versions to replace or incrementally fixup patches in mm-new. The mm-new branch of mm.git is not included in linux-next If a few days of testing in mm-new is successful, the patch will me moved into mm.git's mm-unstable branch, which is included in linux-next Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via various branches at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there most days ------------------------------------------------------ From: SJ Park Subject: mm/damon/core: handle extreme memory state in get_in_active_mem_bp() Date: Tue, 1 Sep 2026 06:18:49 -0700 damos_get_in_active_mem_bp() uses the sum of the active and inactive memory amount as a denominator. In an extreme and unlikely environment, active and inactive memory might be zero. In this case, hence, it results in a divide by zero problem. Avoid it by changing the denominator to one if it is zero, before it is being used. The issue was discovered [1] by Sashiko. Link: https://lore.kernel.org/20260901131850.98037-9-sj@kernel.org Link: https://lore.kernel.org/20260721034756.147011-1-sj@kernel.org [1] Fixes: 4835e2871321 ("mm/damon/core: introduce [in]active memory ratio damos quota goal metric") Signed-off-by: SJ Park Cc: Usama Arif Cc: # 7.0.x Signed-off-by: Andrew Morton --- mm/damon/core.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/mm/damon/core.c~mm-damon-core-handle-extreme-memory-state-in-get_in_active_mem_bp +++ a/mm/damon/core.c @@ -3006,7 +3006,7 @@ static unsigned int damos_get_in_active_ global_node_page_state(NR_LRU_BASE + LRU_ACTIVE_FILE); inactive = global_node_page_state(NR_LRU_BASE + LRU_INACTIVE_ANON) + global_node_page_state(NR_LRU_BASE + LRU_INACTIVE_FILE); - total = active + inactive; + total = max(active + inactive, 1); if (active_ratio) return mult_frac(active, 10000, total); return mult_frac(inactive, 10000, total); _ Patches currently in -mm which might be from sj@kernel.org are mm-damon-core-skip-applying-scheme-if-region-split-for-quota-fails.patch mm-damon-paddr-respect-folio-end-for-damos_stat.patch mm-damon-paddr-respect-folio-end-for-damos-actions-except-stat.patch mm-damon-vaddr-respect-folio-end-for-damos_stat.patch mm-damon-vaddr-respect-folio-end-for-damos_migrate_hotcold.patch mm-damon-core-handle-extreme-memory-state-in-damon_get_node_mem_bp.patch mm-damon-core-handle-extreme-memory-state-in-get_node_memcg_used_bp.patch mm-damon-core-handle-extreme-memory-state-in-get_in_active_mem_bp.patch