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 792C23BCD05 for ; Mon, 31 Aug 2026 18:14:54 +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=1788200095; cv=none; b=OSXlm+oZqQMOhIFc/qVKSwPvck94E8RGn/Wn0m1fUhKBx5DVhDZk0KXb8IMFqTSfa7WcfwMtoNhgB65DnKD14vALOr/qPNYR5Ao2n+yhv0axF2LGp40qWiAX7XvU82knyF8DP+J5F351QfQGR5jDqJPbLnYLVWbHj5227rlPPU8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788200095; c=relaxed/simple; bh=iGmuc4CmScGA/6tEZdkv5Vq3245P2N5tMmR5FUWNofk=; h=From:Subject:To:Cc:In-Reply-To:References:Content-Type:Date: Message-Id; b=bsIfESH1/q+BtYN6pNT1Mr91GXpfKspR3Lm8nMgUD1CE+LnVX+6GpVuK529yzyv04yCzkTs0kJ8Orz4GF30XE628dE0Gp1I5/9tFL7Q7w+7cEkX+NCGgBis9yx0BwhUSvYB2MdpIRUgi68GPXpTfFJcXy/w7RAIOHrYXeoNWB8Q= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=cFJPdscs; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="cFJPdscs" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E934C1F000E9; Mon, 31 Aug 2026 18:14:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788200094; bh=MkOo+fFeNfSE30V9qLuyaGgIjZ+S1tHg29XYJAHdOtc=; h=From:Subject:Reply-To:To:Cc:In-Reply-To:References:Date; b=cFJPdscspiCd2M03jc2/uOlFOXgiqvD/E6couDfOPFupCsIQFKperha3PYXCHYH45 U7+ub8ZQT6WYmM4PHVyoplk4V2PWlNHiReSWaPxeBLMyAGpQUjC36obT10SEyzPEgr JCwMtpxAeDjICjH62T3Y9co3mUMl2mObQ9DdT0hbxx6AXt/o2qCi9tjLt5/gUgKMXh 2wbBov0ZAq2/P1DDG+KXyMVGt7WKeoQQfzzFJmGQvm8P0cYdO0HXcXImhbKNwAwJeB n0jr2TT1oc/WsDGnxI0IYFmx0Eyo3wDlVcoFVdLOrUSxQDtSWNrpLLvKZJaGvRx+qq hoisEkfHl2z/g== From: sashiko-bot@kernel.org Subject: Re: [RFC PATCH v1.2 4/8] mm/damon/vaddr: respect folio end for DAMOS_STAT Reply-To: sashiko-reviews@lists.linux.dev To: "SJ Park" Cc: damon@lists.linux.dev In-Reply-To: <20260831140254.72004-5-sj@kernel.org> References: <20260831140254.72004-1-sj@kernel.org> <20260831140254.72004-5-sj@kernel.org> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Date: Mon, 31 Aug 2026 18:14:53 +0000 Message-Id: <20260831181453.E934C1F000E9@smtp.kernel.org> Precedence: bulk X-Mailing-List: damon@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: > For applying DAMOS_STAT action to a region, DAMON virtual address space > operation set (vaddr) calls walk_page_range[_vma]() for the region. The > pmd walk entry function, namely damon_va_stat_pmd_entry(), applies DAMOS > filters to folios of addresses of the region in the pmd. It starts from > the walking address and advances the address by the size of the folio of > the address until it goes out of the pmd or the region. >=20 > Let's suppose it is for the first pmd of the region, and the region > start address is in the middle of a large folio. Also, the next folios > are small. Then, some of the next folios could be skipped. Fix the > issue by advancing the address to exactly the start address of the next > folio. >=20 > The user impact is that the DAMOS_STAT-based page level monitoring > results become inaccurate. Since the page level monitoring is supposed > to provide relatively high precision, this is definitely a problem. It > is arguably not critical since it is only monitoring quality > degradation. >=20 > The issue was discovered [1] by Sashiko. >=20 > [1] https://lore.kernel.org/20260514015053.149396-1-sj@kernel.org >=20 > Fixes: 63f39737d1e3 ("mm/damon/vaddr: support stat-purpose DAMOS filters") > Cc: # 6.18.x > Signed-off-by: SJ Park Sashiko has reviewed this patch and found no issues. It looks great! --=20 Sashiko AI review =C2=B7 https://sashiko.dev/#/patchset/20260831140254.7200= 4-1-sj@kernel.org?part=3D4