mm/damon/reclaim: use min_sz_region for core address alignment when setting regions

When setting regions in DAMON_RECLAIM, DAMON_MIN_REGION will be applied 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_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, use min_sz_region for core address alignment when
setting regions.

Link: https://lkml.kernel.org/r/20251020130125.2875164-3-yanquanmin1@huawei.com
Fixes: 7db551fcfb2a ("mm/damon/reclaim: support addr_unit for DAMON_RECLAIM")
Signed-off-by: Quanmin Yan <yanquanmin1@huawei.com>
Reviewed-by: SeongJae Park <sj@kernel.org>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: ze zuo <zuoze1@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/damon/reclaim.c b/mm/damon/reclaim.c
index e30811cafe90cd465efd77ee4340c6109a5a6b9d..36a582e09eaef178173947760c99b22dcf277ccd 100644 (file)
--- a/mm/damon/reclaim.c
+++ b/mm/damon/reclaim.c
@@ -251,7 +251,7 @@ static int damon_reclaim_apply_parameters(void)
        err = damon_set_region_biggest_system_ram_default(param_target,
                                        &monitor_region_start,
                                        &monitor_region_end,
-                                       DAMON_MIN_REGION);
+                                       param_ctx->min_sz_region);
        if (err)
                goto out;
        err = damon_commit_ctx(ctx, param_ctx);