linux-kernel - [PATCH v2 0/2] mm/damon: fixes for address alignment issues in DAMON_LRU_SORT and DAMON

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Message-ID: <20251020130125.2875164-1-yanquanmin1@huawei.com>
Date: Mon, 20 Oct 2025 21:01:23 +0800
From: Quanmin Yan <yanquanmin1@...wei.com>
To: <sj@...nel.org>
CC: <akpm@...ux-foundation.org>, <damon@...ts.linux.dev>,
	<linux-kernel@...r.kernel.org>, <linux-mm@...ck.org>,
	<yanquanmin1@...wei.com>, <wangkefeng.wang@...wei.com>, <zuoze1@...wei.com>
Subject: [PATCH v2 0/2] mm/damon: fixes for address alignment issues in DAMON_LRU_SORT and DAMON_RECLAIM

In DAMON_LRU_SORT and DAMON_RECLAIM, damon_set_regions() will apply
DAMON_MIN_REGION as the core address alignment, and the monitoring
target address ranges would be aligned on DAMON_MIN_REGION * addr_unit.
When users 1) set addr_unit to a value larger than 1, and 2) set the
monitoring target address range as not aligned on DAMON_MIN_REGION *
addr_unit, it will cause DAMON_LRU_SORT and DAMON_RECLAIM to operate
on unexpectedly large physical address ranges.

For example, if the user sets the monitoring target address range to
[4, 8) and addr_unit as 1024, the aimed monitoring target address range
is [4 KiB, 8 KiB). Assuming DAMON_MIN_REGION is 4096, so resulting
target address range will be [0, 4096) in the DAMON core layer address
system, and [0, 4 MiB) in the physical address space, which is an
unexpected range.

To fix the issue, add a min_sz_region parameter to
damon_set_region_biggest_system_ram_default() and use it when calling
damon_set_regions(), replacing the direct use of DAMON_MIN_REGION.

Changes from v1
(https://lore.kernel.org/all/20251016104717.2194909-1-yanquanmin1@huawei.com/)
- Added more issue description in the commit message.
- Split the original fix patch into two separate patches.

Quanmin Yan (2):
  mm/damon: add a min_sz_region parameter to
    damon_set_region_biggest_system_ram_default()
  mm/damon/reclaim: use min_sz_region for core address alignment when
    setting regions

 include/linux/damon.h | 3 ++-
 mm/damon/core.c       | 6 ++++--
 mm/damon/lru_sort.c   | 3 ++-
 mm/damon/reclaim.c    | 3 ++-
 mm/damon/stat.c       | 3 ++-
 5 files changed, 12 insertions(+), 6 deletions(-)

-- 
2.43.0