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mm/damon: add a min_sz_region parameter to damon_set_region_biggest_system_ram_default() 

Patch series "mm/damon: fixes for address alignment issues in
DAMON_LRU_SORT and DAMON_RECLAIM", v2.

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.


This patch (of 2):

In DAMON_LRU_SORT, 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 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.

Link: https://lkml.kernel.org/r/20251020130125.2875164-1-yanquanmin1@huawei.com
Link: https://lkml.kernel.org/r/20251020130125.2875164-2-yanquanmin1@huawei.com
Fixes: 2e0fe9245d ("mm/damon/lru_sort: support addr_unit for DAMON_LRU_SORT")
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>
This commit is contained in:
Quanmin Yan 2025-10-20 21:01:24 +08:00 committed by Andrew Morton
parent 074f027d15
commit e859a224fa
5 changed files with 12 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
include/linux/damon.h
View File

@ -961,7 +961,8 @@ int damon_call(struct damon_ctx *ctx, struct damon_call_control *control);
int damos_walk(struct damon_ctx *ctx, struct damos_walk_control *control);
int damon_set_region_biggest_system_ram_default(struct damon_target *t,
unsigned long *start, unsigned long *end);
unsigned long *start, unsigned long *end,
unsigned long min_sz_region);
#endif /* CONFIG_DAMON */

6
mm/damon/core.c
View File

@ -2818,6 +2818,7 @@ static bool damon_find_biggest_system_ram(unsigned long *start,
* @t: The monitoring target to set the region.
* @start: The pointer to the start address of the region.
* @end: The pointer to the end address of the region.
* @min_sz_region: Minimum region size.
*
* This function sets the region of @t as requested by @start and @end. If the
* values of @start and @end are zero, however, this function finds the biggest
@ -2828,7 +2829,8 @@ static bool damon_find_biggest_system_ram(unsigned long *start,
* Return: 0 on success, negative error code otherwise.
*/
int damon_set_region_biggest_system_ram_default(struct damon_target *t,
unsigned long *start, unsigned long *end)
unsigned long *start, unsigned long *end,
unsigned long min_sz_region)
{
struct damon_addr_range addr_range;
@ -2841,7 +2843,7 @@ int damon_set_region_biggest_system_ram_default(struct damon_target *t,
addr_range.start = *start;
addr_range.end = *end;
return damon_set_regions(t, &addr_range, 1, DAMON_MIN_REGION);
return damon_set_regions(t, &addr_range, 1, min_sz_region);
}
/*

3
mm/damon/lru_sort.c
View File

@ -242,7 +242,8 @@ static int damon_lru_sort_apply_parameters(void)
err = damon_set_region_biggest_system_ram_default(param_target,
&monitor_region_start,
&monitor_region_end);
&monitor_region_end,
param_ctx->min_sz_region);
if (err)
goto out;
err = damon_commit_ctx(ctx, param_ctx);

3
mm/damon/reclaim.c
View File

@ -250,7 +250,8 @@ static int damon_reclaim_apply_parameters(void)
err = damon_set_region_biggest_system_ram_default(param_target,
&monitor_region_start,
&monitor_region_end);
&monitor_region_end,
DAMON_MIN_REGION);
if (err)
goto out;
err = damon_commit_ctx(ctx, param_ctx);

3
mm/damon/stat.c
View File

@ -188,7 +188,8 @@ static struct damon_ctx *damon_stat_build_ctx(void)
if (!target)
goto free_out;
damon_add_target(ctx, target);
if (damon_set_region_biggest_system_ram_default(target, &start, &end))
if (damon_set_region_biggest_system_ram_default(target, &start, &end,
ctx->min_sz_region))
goto free_out;
return ctx;
free_out: