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 2615F3E7621; Tue, 1 Sep 2026 13:13:36 +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=1788268417; cv=none; b=GDU6HvB0/qrFjM93UMIwcmnK5X2VDuqvdAjHivBjSg/oT05FKe+bBvFQ+xWHTLP+ZdxUpZONUOKIx9w/RGCACLQqbw4LkfHK7189cOLopNGq/80r38T0SnuIiucp/zlJi3YMnA7dsBAib+MnRkqWwkcKwqJtdvb4QXpbp9jokLE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788268417; c=relaxed/simple; bh=3tuXFYxnY5whCfMb9BBfKAgRQ7zxuSBaL+SQQ8TayGI=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=DWuVDCUN24nh61HXPfEgf+MiTNfRf5tE8bSngNfBszPNdxutdiEYBAOWBUXAGfSjuF1DOY6cS2UDHp0GaenMDFvcLbFECVSVTHb3P3Hfvnf9Zjebx8SZmWy8Nizr5OhovmZcTg0tJ3SgC6H9JUKF8AezM3QrD1YKlwwvkru9aMc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=MpeJKmrK; 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="MpeJKmrK" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7F9E71F00A3F; Tue, 1 Sep 2026 13:13:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788268415; bh=l4DJBfV8Ln2wiu4MTHaklCvhtPpo+9nKnYvuVasq3nI=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=MpeJKmrK9iHVcoS550Knf/Mlx3E0FIKosfejJKu6aHXOgY8rXc69/9aUaYT6efHrh 318yLkiCl+yee/KmUKnyfNEhOXMrlAqQqVtymWWhNQsV3d+Cjqry887CtY6hOzaIt7 QaAyDFo1SdZRMTt81syDLPKzwjjQXP1PN0tqFIDd21PZ9Y3IEjycwwxJPYwtPA3r+f XD7VzjFO2gS24GALcmEwiUy3AkyUxwl2II0b7NhFjwGRh89maVLHrSnvxKd1KV+C0x +I8DT3ansh/JMHAJ0niHX4xbLfGfrsQjh5wWlAQen97xpHuCuButa+KiEztUyVpqNN R4UfKFv61ey1A== From: SJ Park To: Andrew Morton Cc: SJ Park , stable@vger.kernel.org, Usama Arif , damon@lists.linux.dev, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: [PATCH 2/7] mm/damon/paddr: respect folio end for DAMOS actions except STAT Date: Tue, 1 Sep 2026 06:13:19 -0700 Message-ID: <20260901131326.97615-3-sj@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260901131326.97615-1-sj@kernel.org> References: <20260901131326.97615-1-sj@kernel.org> Precedence: bulk X-Mailing-List: damon@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit A few functions for applying DAMOS actions including pageout, lru_[de]prio and migrate_{hot,cold} in DAMON physical address space operation set (paddr) collect folios of the given region by getting the folios of region-internal addresses. Then, those functions apply the action to the collected folios at once. The collection starts from the region start address and advances the address by the size of the folio of the address until it goes out of the region. If the start address is in the middle of a large folio, and if the next folios are small, some of the next folios could be skipped. Fix the issue by advancing the address to exactly the start address of the next folio. The user impact is that DAMOS action is applied to less than expected amount of memory. Given the best effort nature of DAMON, it is no big problem, but it is clearly a bug that is better to be fixed. The issue was discovered [1] by Sashiko. [1] https://lore.kernel.org/20260517234112.89245-1-sj@kernel.org Fixes: 3a06696305e7 ("mm/damon/ops: have damon_get_folio return folio even for tail pages") Cc: # 6.15.x Signed-off-by: SJ Park --- mm/damon/paddr.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/mm/damon/paddr.c b/mm/damon/paddr.c index 2ab7b3842701e..9ddd1ec8202b7 100644 --- a/mm/damon/paddr.c +++ b/mm/damon/paddr.c @@ -264,7 +264,7 @@ static unsigned long damon_pa_pageout(struct damon_region *r, else list_add(&folio->lru, &folio_list); put_folio: - addr += folio_size(folio); + addr = PFN_PHYS(folio_pfn(folio)) + folio_size(folio); folio_put(folio); } if (install_young_filter) @@ -302,7 +302,7 @@ static inline unsigned long damon_pa_de_activate( folio_deactivate(folio); applied += folio_nr_pages(folio); put_folio: - addr += folio_size(folio); + addr = PFN_PHYS(folio_pfn(folio)) + folio_size(folio); folio_put(folio); } s->last_applied = folio; @@ -350,7 +350,7 @@ static unsigned long damon_pa_migrate(struct damon_region *r, folio_is_file_lru(folio)); list_add(&folio->lru, &folio_list); put_folio: - addr += folio_size(folio); + addr = PFN_PHYS(folio_pfn(folio)) + folio_size(folio); folio_put(folio); } applied = damon_migrate_pages(&folio_list, s->target_nid); -- 2.47.3