Re: [RFC PATCH v1 2/4] mm/damon: Support for synchrounous huge pages collapse

[Gutierrez Asier <gutierrez.asier@huawei-partners.com>]

On 2/3/2026 4:23 AM, SeongJae Park wrote:
> On Mon, 2 Feb 2026 14:56:47 +0000 <gutierrez.asier@huawei-partners.com> wrote:
> 
>> From: Asier Gutierrez <gutierrez.asier@huawei-partners.com>
>>
>> * Support for huge pages collapse, which will be used by
>>   dynamic_hugepages module.
>>
>> * Include the new module for compilation
>>
>> Signed-off-by: Asier Gutierrez <gutierrez.asier@huawei-partners.com>
>> Co-developed-by: Anatoly Stepanov <stepanov.anatoly@huawei.com>
>> ---
>>  include/linux/damon.h | 1 +
>>  mm/damon/Kconfig      | 7 +++++++
>>  mm/damon/Makefile     | 1 +
>>  mm/damon/vaddr.c      | 3 +++
>>  4 files changed, 12 insertions(+)
>>
>> diff --git a/include/linux/damon.h b/include/linux/damon.h
>> index 3813373a9200..de5a994f92c2 100644
>> --- a/include/linux/damon.h
>> +++ b/include/linux/damon.h
>> @@ -142,6 +142,7 @@ enum damos_action {
>>  	DAMOS_LRU_DEPRIO,
>>  	DAMOS_MIGRATE_HOT,
>>  	DAMOS_MIGRATE_COLD,
>> +	DAMOS_COLLAPSE,
> 
> Please update the kernel-doc comments for this new action, by the time you drop
> the RFC tag from this patch series.
> 
>>  	DAMOS_STAT,		/* Do nothing but only record the stat */
>>  	NR_DAMOS_ACTIONS,
>>  };
>> diff --git a/mm/damon/Kconfig b/mm/damon/Kconfig
>> index 8c868f7035fc..2355aacb6d12 100644
>> --- a/mm/damon/Kconfig
>> +++ b/mm/damon/Kconfig
>> @@ -110,4 +110,11 @@ config DAMON_STAT_ENABLED_DEFAULT
>>  	  Whether to enable DAMON_STAT by default.  Users can disable it in
>>  	  boot or runtime using its 'enabled' parameter.
>>  
>> +config DAMON_HOT_HUGEPAGE
>> +	bool "Build DAMON-based collapse of hot regions (DAMON_HOT_HUGEPAGES)"
>> +	depends on DAMON_VADDR
>> +	help
>> +	 Collapse hot region into huge pages. Hot regions are determined by
>> +	 DAMON-based sampling
>> +
> 
> Apparently you wanted to introduce the above change on the next patch, but
> mistakenly added here?
> 
> I'm also feeling the name might be better to be simpler.  What about... say,
> just DAMON_HUGEPAGE?  We might want to extend that for general access-aware
> huge pages.

I will move the build stuff into a different commit for the next RFC series.

I agree with the name change, I will do it.

>>  endmenu
>> diff --git a/mm/damon/Makefile b/mm/damon/Makefile
>> index d8d6bf5f8bff..998bddc17819 100644
>> --- a/mm/damon/Makefile
>> +++ b/mm/damon/Makefile
>> @@ -7,3 +7,4 @@ obj-$(CONFIG_DAMON_SYSFS)	+= sysfs-common.o sysfs-schemes.o sysfs.o
>>  obj-$(CONFIG_DAMON_RECLAIM)	+= modules-common.o reclaim.o
>>  obj-$(CONFIG_DAMON_LRU_SORT)	+= modules-common.o lru_sort.o
>>  obj-$(CONFIG_DAMON_STAT)	+= modules-common.o stat.o
>> +obj-$(CONFIG_DAMON_HOT_HUGEPAGE)	+= modules-common.o dynamic_hugepages.o
> 
> Ditto.
> 
>> diff --git a/mm/damon/vaddr.c b/mm/damon/vaddr.c
>> index 23ed738a0bd6..4acbc1a6a5be 100644
>> --- a/mm/damon/vaddr.c
>> +++ b/mm/damon/vaddr.c
>> @@ -970,6 +970,9 @@ static unsigned long damon_va_apply_scheme(struct damon_ctx *ctx,
>>  	case DAMOS_NOHUGEPAGE:
>>  		madv_action = MADV_NOHUGEPAGE;
>>  		break;
>> +	case DAMOS_COLLAPSE:
>> +		madv_action = MADV_COLLAPSE;
>> +		break;
>>  	case DAMOS_MIGRATE_HOT:
>>  	case DAMOS_MIGRATE_COLD:
>>  		return damos_va_migrate(t, r, scheme, sz_filter_passed);
>> -- 
>> 2.43.0
> 
> 
> Thanks,
> SJ
> 
> [...]
> 

-- 
Asier Gutierrez
Huawei