Re: [PATCH v2 0/2] mm/damon: fixes for address alignment issues in DAMON_LRU_SORT and DAMON_RECLAIM

[SeongJae Park <sj@kernel.org>]

On Mon, 20 Oct 2025 21:01:23 +0800 Quanmin Yan <yanquanmin1@huawei.com> wrote:

> 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.

Thank you for nicely revising this!


Thanks,
SJ

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