[PATCH v2 00/11] mm/damon: support ARM32 with LPAE

[PATCH v2 00/11] mm/damon: support ARM32 with LPAE

[Quanmin Yan]

Previously, DAMON's physical address space monitoring only supported
memory ranges below 4GB on LPAE-enabled systems. This was due to
the use of 'unsigned long' in 'struct damon_addr_range', which is
32-bit on ARM32 even with LPAE enabled[1].

To add DAMON support for ARM32 with LPAE enabled, a new core layer
parameter called 'addr_unit' was introduced[2]. Operations set layer
can translate a core layer address to the real address by multiplying
the parameter value to the core layer address. Support of the parameter
is up to each operations layer implementation, though. For example,
operations set implementations for virtual address space can simply
ignore the parameter. Add the support on paddr, which is the DAMON
operations set implementation for the physical address space, as we have
a clear use case for that.

[1]https://lore.kernel.org/all/20250408075553.959388-1-zuoze1@huawei.com/
[2]https://lore.kernel.org/all/20250416042551.158131-1-sj@kernel.org/

Changes from v1
(https://lore.kernel.org/all/20250821105159.2503894-1-yanquanmin1@huawei.com/)
- Set dst->min_sz_region as src->min_sz_region in damon_commit_ctx().
- Fixed the incorrect 'min_region' in the commit message.

Changes from RFC v2
(https://lore.kernel.org/all/20250820080623.3799131-1-yanquanmin1@huawei.com/)
- Rename 'min_region' to 'min_sz_region'.
- Separate the overflow prevention in damos_set_effective_quota() from
  this series.
- Drop RFC tag.

Changes from RFC v1
(https://lore.kernel.org/all/20250813050706.1564229-1-yanquanmin1@huawei.com/)
- Set DAMOS_PAGEOUT, DAMOS_LRU_[DE]PRIO, DAMOS_MIGRATE_{HOT,COLD} and
  DAMOS_STAT stat in core address unit.
- Pass ctx->min_region value to replace the original synchronization.
- Drop the DAMOS stats type changes, keep them as 'unsigned long' type.
- Separate add addr_unit support for DAMON_RECLAIM and LRU_SORT from
  this patch series.

Quanmin Yan (1):
  mm/damon: add damon_ctx->min_sz_region

SeongJae Park (10):
  mm/damon/core: add damon_ctx->addr_unit
  mm/damon/paddr: support addr_unit for access monitoring
  mm/damon/paddr: support addr_unit for DAMOS_PAGEOUT
  mm/damon/paddr: support addr_unit for DAMOS_LRU_[DE]PRIO
  mm/damon/paddr: support addr_unit for MIGRATE_{HOT,COLD}
  mm/damon/paddr: support addr_unit for DAMOS_STAT
  mm/damon/sysfs: implement addr_unit file under context dir
  Docs/mm/damon/design: document 'address unit' parameter
  Docs/admin-guide/mm/damon/usage: document addr_unit file
  Docs/ABI/damon: document addr_unit file

 .../ABI/testing/sysfs-kernel-mm-damon         |   7 ++
 Documentation/admin-guide/mm/damon/usage.rst  |  11 +-
 Documentation/mm/damon/design.rst             |  16 ++-
 include/linux/damon.h                         |   7 +-
 mm/damon/core.c                               |  70 +++++++-----
 mm/damon/paddr.c                              | 106 +++++++++++-------
 mm/damon/sysfs.c                              |  41 ++++++-
 mm/damon/tests/core-kunit.h                   |  21 ++--
 mm/damon/tests/vaddr-kunit.h                  |   2 +-
 mm/damon/vaddr.c                              |   2 +-
 10 files changed, 191 insertions(+), 92 deletions(-)

-- 
2.43.0

[PATCH v2 01/11] mm/damon/core: add damon_ctx->addr_unit

[Quanmin Yan]

From: SeongJae Park <sj@kernel.org>

In some cases, some of the real address that handled by the underlying
operations set cannot be handled by DAMON since it uses only 'unsinged
long' as the address type.  Using DAMON for physical address space
monitoring of 32 bit ARM devices with large physical address extension
(LPAE) is one example[1].

Add a parameter name 'addr_unit' to core layer to help such cases.
DAMON core API callers can set it as the scale factor that will be used
by the operations set for translating the core layer's addresses to the
real address by multiplying the parameter value to the core layer
address.  Support of the parameter is up to each operations set layer.
The support from the physical address space operations set (paddr) will
be added with following commits.

[1] https://lore.kernel.org/20250408075553.959388-1-zuoze1@huawei.com

Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Quanmin Yan <yanquanmin1@huawei.com>
Reviewed-by: SeongJae Park <sj@kernel.org>
---
 include/linux/damon.h | 3 ++-
 mm/damon/core.c       | 3 +++
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/include/linux/damon.h b/include/linux/damon.h
index d01bfee80bd6..6fa52f7495d9 100644
--- a/include/linux/damon.h
+++ b/include/linux/damon.h
@@ -746,7 +746,7 @@ struct damon_attrs {
  * Accesses to other fields must be protected by themselves.
  *
  * @ops:	Set of monitoring operations for given use cases.
- *
+ * @addr_unit:	Scale factor for core to ops address conversion.
  * @adaptive_targets:	Head of monitoring targets (&damon_target) list.
  * @schemes:		Head of schemes (&damos) list.
  */
@@ -788,6 +788,7 @@ struct damon_ctx {
 	struct mutex kdamond_lock;
 
 	struct damon_operations ops;
+	unsigned long addr_unit;
 
 	struct list_head adaptive_targets;
 	struct list_head schemes;
diff --git a/mm/damon/core.c b/mm/damon/core.c
index cb41fddca78c..8f8aa84953ac 100644
--- a/mm/damon/core.c
+++ b/mm/damon/core.c
@@ -544,6 +544,8 @@ struct damon_ctx *damon_new_ctx(void)
 	ctx->attrs.min_nr_regions = 10;
 	ctx->attrs.max_nr_regions = 1000;
 
+	ctx->addr_unit = 1;
+
 	INIT_LIST_HEAD(&ctx->adaptive_targets);
 	INIT_LIST_HEAD(&ctx->schemes);
 
@@ -1245,6 +1247,7 @@ int damon_commit_ctx(struct damon_ctx *dst, struct damon_ctx *src)
 			return err;
 	}
 	dst->ops = src->ops;
+	dst->addr_unit = src->addr_unit;
 
 	return 0;
 }
-- 
2.43.0

[PATCH v2 02/11] mm/damon/paddr: support addr_unit for access monitoring

[Quanmin Yan]

From: SeongJae Park <sj@kernel.org>

Add support of addr_unit paramer for access monitoing operations of
paddr.

Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Quanmin Yan <yanquanmin1@huawei.com>
Reviewed-by: SeongJae Park <sj@kernel.org>
---
 mm/damon/paddr.c | 32 +++++++++++++++++++++-----------
 1 file changed, 21 insertions(+), 11 deletions(-)

diff --git a/mm/damon/paddr.c b/mm/damon/paddr.c
index 0b67d9321460..d497373c2bd2 100644
--- a/mm/damon/paddr.c
+++ b/mm/damon/paddr.c
@@ -18,7 +18,13 @@
 #include "../internal.h"
 #include "ops-common.h"
 
-static void damon_pa_mkold(unsigned long paddr)
+static phys_addr_t damon_pa_phys_addr(
+		unsigned long addr, unsigned long addr_unit)
+{
+	return (phys_addr_t)addr * addr_unit;
+}
+
+static void damon_pa_mkold(phys_addr_t paddr)
 {
 	struct folio *folio = damon_get_folio(PHYS_PFN(paddr));
 
@@ -29,11 +35,12 @@ static void damon_pa_mkold(unsigned long paddr)
 	folio_put(folio);
 }
 
-static void __damon_pa_prepare_access_check(struct damon_region *r)
+static void __damon_pa_prepare_access_check(struct damon_region *r,
+		unsigned long addr_unit)
 {
 	r->sampling_addr = damon_rand(r->ar.start, r->ar.end);
 
-	damon_pa_mkold(r->sampling_addr);
+	damon_pa_mkold(damon_pa_phys_addr(r->sampling_addr, addr_unit));
 }
 
 static void damon_pa_prepare_access_checks(struct damon_ctx *ctx)
@@ -43,11 +50,11 @@ static void damon_pa_prepare_access_checks(struct damon_ctx *ctx)
 
 	damon_for_each_target(t, ctx) {
 		damon_for_each_region(r, t)
-			__damon_pa_prepare_access_check(r);
+			__damon_pa_prepare_access_check(r, ctx->addr_unit);
 	}
 }
 
-static bool damon_pa_young(unsigned long paddr, unsigned long *folio_sz)
+static bool damon_pa_young(phys_addr_t paddr, unsigned long *folio_sz)
 {
 	struct folio *folio = damon_get_folio(PHYS_PFN(paddr));
 	bool accessed;
@@ -62,23 +69,25 @@ static bool damon_pa_young(unsigned long paddr, unsigned long *folio_sz)
 }
 
 static void __damon_pa_check_access(struct damon_region *r,
-		struct damon_attrs *attrs)
+		struct damon_attrs *attrs, unsigned long addr_unit)
 {
-	static unsigned long last_addr;
+	static phys_addr_t last_addr;
 	static unsigned long last_folio_sz = PAGE_SIZE;
 	static bool last_accessed;
+	phys_addr_t sampling_addr = damon_pa_phys_addr(
+			r->sampling_addr, addr_unit);
 
 	/* If the region is in the last checked page, reuse the result */
 	if (ALIGN_DOWN(last_addr, last_folio_sz) ==
-				ALIGN_DOWN(r->sampling_addr, last_folio_sz)) {
+				ALIGN_DOWN(sampling_addr, last_folio_sz)) {
 		damon_update_region_access_rate(r, last_accessed, attrs);
 		return;
 	}
 
-	last_accessed = damon_pa_young(r->sampling_addr, &last_folio_sz);
+	last_accessed = damon_pa_young(sampling_addr, &last_folio_sz);
 	damon_update_region_access_rate(r, last_accessed, attrs);
 
-	last_addr = r->sampling_addr;
+	last_addr = sampling_addr;
 }
 
 static unsigned int damon_pa_check_accesses(struct damon_ctx *ctx)
@@ -89,7 +98,8 @@ static unsigned int damon_pa_check_accesses(struct damon_ctx *ctx)
 
 	damon_for_each_target(t, ctx) {
 		damon_for_each_region(r, t) {
-			__damon_pa_check_access(r, &ctx->attrs);
+			__damon_pa_check_access(
+					r, &ctx->attrs, ctx->addr_unit);
 			max_nr_accesses = max(r->nr_accesses, max_nr_accesses);
 		}
 	}
-- 
2.43.0

[PATCH v2 03/11] mm/damon/paddr: support addr_unit for DAMOS_PAGEOUT

[Quanmin Yan]

From: SeongJae Park <sj@kernel.org>

Add support of addr_unit for DAMOS_PAGEOUT action handling from the
DAMOS operation implementation for the physical address space.

Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Quanmin Yan <yanquanmin1@huawei.com>
Reviewed-by: SeongJae Park <sj@kernel.org>
---
 mm/damon/paddr.c | 17 ++++++++++-------
 1 file changed, 10 insertions(+), 7 deletions(-)

diff --git a/mm/damon/paddr.c b/mm/damon/paddr.c
index d497373c2bd2..826c2064dbfd 100644
--- a/mm/damon/paddr.c
+++ b/mm/damon/paddr.c
@@ -135,10 +135,11 @@ static bool damon_pa_invalid_damos_folio(struct folio *folio, struct damos *s)
 	return false;
 }
 
-static unsigned long damon_pa_pageout(struct damon_region *r, struct damos *s,
+static unsigned long damon_pa_pageout(struct damon_region *r,
+		unsigned long addr_unit, struct damos *s,
 		unsigned long *sz_filter_passed)
 {
-	unsigned long addr, applied;
+	phys_addr_t addr, applied;
 	LIST_HEAD(folio_list);
 	bool install_young_filter = true;
 	struct damos_filter *filter;
@@ -159,8 +160,8 @@ static unsigned long damon_pa_pageout(struct damon_region *r, struct damos *s,
 		damos_add_filter(s, filter);
 	}
 
-	addr = r->ar.start;
-	while (addr < r->ar.end) {
+	addr = damon_pa_phys_addr(r->ar.start, addr_unit);
+	while (addr < damon_pa_phys_addr(r->ar.end, addr_unit)) {
 		folio = damon_get_folio(PHYS_PFN(addr));
 		if (damon_pa_invalid_damos_folio(folio, s)) {
 			addr += PAGE_SIZE;
@@ -170,7 +171,7 @@ static unsigned long damon_pa_pageout(struct damon_region *r, struct damos *s,
 		if (damos_pa_filter_out(s, folio))
 			goto put_folio;
 		else
-			*sz_filter_passed += folio_size(folio);
+			*sz_filter_passed += folio_size(folio) / addr_unit;
 
 		folio_clear_referenced(folio);
 		folio_test_clear_young(folio);
@@ -189,7 +190,7 @@ static unsigned long damon_pa_pageout(struct damon_region *r, struct damos *s,
 	applied = reclaim_pages(&folio_list);
 	cond_resched();
 	s->last_applied = folio;
-	return applied * PAGE_SIZE;
+	return applied * PAGE_SIZE / addr_unit;
 }
 
 static inline unsigned long damon_pa_mark_accessed_or_deactivate(
@@ -302,9 +303,11 @@ static unsigned long damon_pa_apply_scheme(struct damon_ctx *ctx,
 		struct damon_target *t, struct damon_region *r,
 		struct damos *scheme, unsigned long *sz_filter_passed)
 {
+	unsigned long aunit = ctx->addr_unit;
+
 	switch (scheme->action) {
 	case DAMOS_PAGEOUT:
-		return damon_pa_pageout(r, scheme, sz_filter_passed);
+		return damon_pa_pageout(r, aunit, scheme, sz_filter_passed);
 	case DAMOS_LRU_PRIO:
 		return damon_pa_mark_accessed(r, scheme, sz_filter_passed);
 	case DAMOS_LRU_DEPRIO:
-- 
2.43.0

Re: [PATCH v2 03/11] mm/damon/paddr: support addr_unit for DAMOS_PAGEOUT

[SeongJae Park]

On Fri, 22 Aug 2025 17:34:11 +0800 Quanmin Yan <yanquanmin1@huawei.com> wrote:

> From: SeongJae Park <sj@kernel.org>
> 
> Add support of addr_unit for DAMOS_PAGEOUT action handling from the
> DAMOS operation implementation for the physical address space.
[...]
> -	return applied * PAGE_SIZE;
> +	return applied * PAGE_SIZE / addr_unit;
>  }

Kernel test robot [1] found this can cause __udivdi3 linking issue.  Andrew,
could you please add the below attached fixup?

[1] https://lore.kernel.org/oe-kbuild-all/202508241831.EKwdwXZL-lkp@intel.com/


Thanks,
SJ

[...]

==== Attachment 0 (0001-mm-damon-paddr-use-do_div-on-i386-for-damon_pa_pageo.patch) ====
From hackermail Thu Jan  1 00:00:00 1970
From: SeongJae Park <sj@kernel.org>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: SeongJae Park <sj@kernel.org>
Cc: damon@lists.linux.dev
Cc: kernel-team@meta.com
Cc: linux-kernel@vger.kernel.org
Cc: linux-mm@kvack.org
Date: Mon, 25 Aug 2025 07:41:33 -0700
Subject: [PATCH 1/3] mm/damon/paddr: use do_div() on i386 for damon_pa_pageout()
         return value

Otherwise, __udidi3 linking problem happens on certain configs.

Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202508241831.EKwdwXZL-lkp@intel.com/
Signed-off-by: SeongJae Park <sj@kernel.org>
---
 mm/damon/paddr.c | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/mm/damon/paddr.c b/mm/damon/paddr.c
index 5fad2f9a99a0..09c87583af6c 100644
--- a/mm/damon/paddr.c
+++ b/mm/damon/paddr.c
@@ -135,6 +135,18 @@ static bool damon_pa_invalid_damos_folio(struct folio *folio, struct damos *s)
 	return false;
 }
 
+/* convert physical address to core-layer address */
+static unsigned long damon_pa_core_addr(phys_addr_t pa,
+		unsigned long addr_unit)
+{
+#ifdef __i386__
+	do_div(pa, addr_unit);
+	return pa;
+#else
+	return pa / addr_unit;
+#endif
+}
+
 static unsigned long damon_pa_pageout(struct damon_region *r,
 		unsigned long addr_unit, struct damos *s,
 		unsigned long *sz_filter_passed)
@@ -190,7 +202,7 @@ static unsigned long damon_pa_pageout(struct damon_region *r,
 	applied = reclaim_pages(&folio_list);
 	cond_resched();
 	s->last_applied = folio;
-	return applied * PAGE_SIZE / addr_unit;
+	return damon_pa_core_addr(applied * PAGE_SIZE, addr_unit);
 }
 
 static inline unsigned long damon_pa_mark_accessed_or_deactivate(
-- 
2.39.5

Re: [PATCH v2 03/11] mm/damon/paddr: support addr_unit for DAMOS_PAGEOUT

[Quanmin Yan]

在 2025/8/25 23:12, SeongJae Park 写道:
> On Fri, 22 Aug 2025 17:34:11 +0800 Quanmin Yan <yanquanmin1@huawei.com> wrote:
>
>> From: SeongJae Park <sj@kernel.org>
>>
>> Add support of addr_unit for DAMOS_PAGEOUT action handling from the
>> DAMOS operation implementation for the physical address space.
> [...]
>> -	return applied * PAGE_SIZE;
>> +	return applied * PAGE_SIZE / addr_unit;
>>   }
> Kernel test robot [1] found this can cause __udivdi3 linking issue.  Andrew,
> could you please add the below attached fixup?
>
> [1] https://lore.kernel.org/oe-kbuild-all/202508241831.EKwdwXZL-lkp@intel.com/
>
>
> Thanks,
> SJ
>
> [...]
>
> ==== Attachment 0 (0001-mm-damon-paddr-use-do_div-on-i386-for-damon_pa_pageo.patch) ====
>  From hackermail Thu Jan  1 00:00:00 1970
> From: SeongJae Park <sj@kernel.org>
> To: Andrew Morton <akpm@linux-foundation.org>
> Cc: SeongJae Park <sj@kernel.org>
> Cc: damon@lists.linux.dev
> Cc: kernel-team@meta.com
> Cc: linux-kernel@vger.kernel.org
> Cc: linux-mm@kvack.org
> Date: Mon, 25 Aug 2025 07:41:33 -0700
> Subject: [PATCH 1/3] mm/damon/paddr: use do_div() on i386 for damon_pa_pageout()
>           return value
>
> Otherwise, __udidi3 linking problem happens on certain configs.
>
> Reported-by: kernel test robot <lkp@intel.com>
> Closes: https://lore.kernel.org/oe-kbuild-all/202508241831.EKwdwXZL-lkp@intel.com/
> Signed-off-by: SeongJae Park <sj@kernel.org>
> ---
>   mm/damon/paddr.c | 14 +++++++++++++-
>   1 file changed, 13 insertions(+), 1 deletion(-)
>
> diff --git a/mm/damon/paddr.c b/mm/damon/paddr.c
> index 5fad2f9a99a0..09c87583af6c 100644
> --- a/mm/damon/paddr.c
> +++ b/mm/damon/paddr.c
> @@ -135,6 +135,18 @@ static bool damon_pa_invalid_damos_folio(struct folio *folio, struct damos *s)
>   	return false;
>   }
>   
> +/* convert physical address to core-layer address */
> +static unsigned long damon_pa_core_addr(phys_addr_t pa,
> +		unsigned long addr_unit)
> +{
> +#ifdef __i386__

Can we use the following condition instead?

#if !defined(CONFIG_64BIT) && defined(CONFIG_PHYS_ADDR_T_64BIT)

Thanks,
Quanmin Yan

> +	do_div(pa, addr_unit);
> +	return pa;
> +#else
> +	return pa / addr_unit;
> +#endif
> +}
> +
>   static unsigned long damon_pa_pageout(struct damon_region *r,
>   		unsigned long addr_unit, struct damos *s,
>   		unsigned long *sz_filter_passed)
> @@ -190,7 +202,7 @@ static unsigned long damon_pa_pageout(struct damon_region *r,
>   	applied = reclaim_pages(&folio_list);
>   	cond_resched();
>   	s->last_applied = folio;
> -	return applied * PAGE_SIZE / addr_unit;
> +	return damon_pa_core_addr(applied * PAGE_SIZE, addr_unit);
>   }
>   
>   static inline unsigned long damon_pa_mark_accessed_or_deactivate(

Re: [PATCH v2 03/11] mm/damon/paddr: support addr_unit for DAMOS_PAGEOUT

[SeongJae Park]

On Tue, 26 Aug 2025 11:16:56 +0800 Quanmin Yan <yanquanmin1@huawei.com> wrote:

> 
> 在 2025/8/25 23:12, SeongJae Park 写道:
> > On Fri, 22 Aug 2025 17:34:11 +0800 Quanmin Yan <yanquanmin1@huawei.com> wrote:
[...]
> > ==== Attachment 0 (0001-mm-damon-paddr-use-do_div-on-i386-for-damon_pa_pageo.patch) ====
> >  From hackermail Thu Jan  1 00:00:00 1970
> > From: SeongJae Park <sj@kernel.org>
> > To: Andrew Morton <akpm@linux-foundation.org>
> > Cc: SeongJae Park <sj@kernel.org>
> > Cc: damon@lists.linux.dev
> > Cc: kernel-team@meta.com
> > Cc: linux-kernel@vger.kernel.org
> > Cc: linux-mm@kvack.org
> > Date: Mon, 25 Aug 2025 07:41:33 -0700
> > Subject: [PATCH 1/3] mm/damon/paddr: use do_div() on i386 for damon_pa_pageout()
> >           return value
> >
> > Otherwise, __udidi3 linking problem happens on certain configs.
> >
> > Reported-by: kernel test robot <lkp@intel.com>
> > Closes: https://lore.kernel.org/oe-kbuild-all/202508241831.EKwdwXZL-lkp@intel.com/
> > Signed-off-by: SeongJae Park <sj@kernel.org>
> > ---
> >   mm/damon/paddr.c | 14 +++++++++++++-
> >   1 file changed, 13 insertions(+), 1 deletion(-)
> >
> > diff --git a/mm/damon/paddr.c b/mm/damon/paddr.c
> > index 5fad2f9a99a0..09c87583af6c 100644
> > --- a/mm/damon/paddr.c
> > +++ b/mm/damon/paddr.c
> > @@ -135,6 +135,18 @@ static bool damon_pa_invalid_damos_folio(struct folio *folio, struct damos *s)
> >   	return false;
> >   }
> >   
> > +/* convert physical address to core-layer address */
> > +static unsigned long damon_pa_core_addr(phys_addr_t pa,
> > +		unsigned long addr_unit)
> > +{
> > +#ifdef __i386__
> 
> Can we use the following condition instead?
> 
> #if !defined(CONFIG_64BIT) && defined(CONFIG_PHYS_ADDR_T_64BIT)

To my understanding, this issue happens only on i386, not every 32bit
architectures.  So I think i386 specific condition is better.


Thanks,
SJ

[...]

Re: [PATCH v2 03/11] mm/damon/paddr: support addr_unit for DAMOS_PAGEOUT

[Quanmin Yan]

Hi SJ,

在 2025/8/26 11:21, SeongJae Park 写道:
> [...]
>
>>> ==== Attachment 0 (0001-mm-damon-paddr-use-do_div-on-i386-for-damon_pa_pageo.patch) ====
>>>   From hackermail Thu Jan  1 00:00:00 1970
>>> From: SeongJae Park <sj@kernel.org>
>>> To: Andrew Morton <akpm@linux-foundation.org>
>>> Cc: SeongJae Park <sj@kernel.org>
>>> Cc: damon@lists.linux.dev
>>> Cc: kernel-team@meta.com
>>> Cc: linux-kernel@vger.kernel.org
>>> Cc: linux-mm@kvack.org
>>> Date: Mon, 25 Aug 2025 07:41:33 -0700
>>> Subject: [PATCH 1/3] mm/damon/paddr: use do_div() on i386 for damon_pa_pageout()
>>>            return value
>>>
>>> Otherwise, __udidi3 linking problem happens on certain configs.
>>>
>>> Reported-by: kernel test robot <lkp@intel.com>
>>> Closes: https://lore.kernel.org/oe-kbuild-all/202508241831.EKwdwXZL-lkp@intel.com/
>>> Signed-off-by: SeongJae Park <sj@kernel.org>
>>> ---
>>>    mm/damon/paddr.c | 14 +++++++++++++-
>>>    1 file changed, 13 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/mm/damon/paddr.c b/mm/damon/paddr.c
>>> index 5fad2f9a99a0..09c87583af6c 100644
>>> --- a/mm/damon/paddr.c
>>> +++ b/mm/damon/paddr.c
>>> @@ -135,6 +135,18 @@ static bool damon_pa_invalid_damos_folio(struct folio *folio, struct damos *s)
>>>    	return false;
>>>    }
>>>    
>>> +/* convert physical address to core-layer address */
>>> +static unsigned long damon_pa_core_addr(phys_addr_t pa,
>>> +		unsigned long addr_unit)
>>> +{
>>> +#ifdef __i386__
>> Can we use the following condition instead?
>>
>> #if !defined(CONFIG_64BIT) && defined(CONFIG_PHYS_ADDR_T_64BIT)
> To my understanding, this issue happens only on i386, not every 32bit
> architectures.  So I think i386 specific condition is better.

I understand. However, the aforementioned general condition is essential,
and we should propose a new patch to address this. After introducing addr_unit,
any 32-bit architecture should support monitoring of 64-bit phys_addr_t.

What do you think should be our next step? Looking forward to your reply.


Thanks,
Quanmin Yan

[...]

Re: [PATCH v2 03/11] mm/damon/paddr: support addr_unit for DAMOS_PAGEOUT

[SeongJae Park]

On Tue, 26 Aug 2025 12:51:17 +0800 Quanmin Yan <yanquanmin1@huawei.com> wrote:

> Hi SJ,
> 
> 在 2025/8/26 11:21, SeongJae Park 写道:
> > [...]
> >
> >>> ==== Attachment 0 (0001-mm-damon-paddr-use-do_div-on-i386-for-damon_pa_pageo.patch) ====
> >>>   From hackermail Thu Jan  1 00:00:00 1970
> >>> From: SeongJae Park <sj@kernel.org>
> >>> To: Andrew Morton <akpm@linux-foundation.org>
> >>> Cc: SeongJae Park <sj@kernel.org>
> >>> Cc: damon@lists.linux.dev
> >>> Cc: kernel-team@meta.com
> >>> Cc: linux-kernel@vger.kernel.org
> >>> Cc: linux-mm@kvack.org
> >>> Date: Mon, 25 Aug 2025 07:41:33 -0700
> >>> Subject: [PATCH 1/3] mm/damon/paddr: use do_div() on i386 for damon_pa_pageout()
> >>>            return value
> >>>
> >>> Otherwise, __udidi3 linking problem happens on certain configs.
> >>>
> >>> Reported-by: kernel test robot <lkp@intel.com>
> >>> Closes: https://lore.kernel.org/oe-kbuild-all/202508241831.EKwdwXZL-lkp@intel.com/
> >>> Signed-off-by: SeongJae Park <sj@kernel.org>
> >>> ---
> >>>    mm/damon/paddr.c | 14 +++++++++++++-
> >>>    1 file changed, 13 insertions(+), 1 deletion(-)
> >>>
> >>> diff --git a/mm/damon/paddr.c b/mm/damon/paddr.c
> >>> index 5fad2f9a99a0..09c87583af6c 100644
> >>> --- a/mm/damon/paddr.c
> >>> +++ b/mm/damon/paddr.c
> >>> @@ -135,6 +135,18 @@ static bool damon_pa_invalid_damos_folio(struct folio *folio, struct damos *s)
> >>>    	return false;
> >>>    }
> >>>    
> >>> +/* convert physical address to core-layer address */
> >>> +static unsigned long damon_pa_core_addr(phys_addr_t pa,
> >>> +		unsigned long addr_unit)
> >>> +{
> >>> +#ifdef __i386__
> >> Can we use the following condition instead?
> >>
> >> #if !defined(CONFIG_64BIT) && defined(CONFIG_PHYS_ADDR_T_64BIT)
> > To my understanding, this issue happens only on i386, not every 32bit
> > architectures.  So I think i386 specific condition is better.
> 
> I understand. However, the aforementioned general condition is essential,
> and we should propose a new patch to address this. After introducing addr_unit,
> any 32-bit architecture should support monitoring of 64-bit phys_addr_t.

The issue is that we cannot divide 64bit values with plain '/' operator on
"i386", and hence this patch makes it to use do_div() instead of '/' on "i386".
No such or other problems at supporting 64-bit phys_addr_t is found on other
32bit architectures, to my understanding.  My understanding is that at least
you confirmed that on your arm-based test environment.  So we don't need a new
patch to my understanding.

Am I missing somthing?


Thanks,
SJ

[...]

Re: [PATCH v2 03/11] mm/damon/paddr: support addr_unit for DAMOS_PAGEOUT

[Quanmin Yan]

在 2025/8/26 22:21, SeongJae Park 写道:
> On Tue, 26 Aug 2025 12:51:17 +0800 Quanmin Yan <yanquanmin1@huawei.com> wrote:
>
>> Hi SJ,
>>
>> 在 2025/8/26 11:21, SeongJae Park 写道:
>>> [...]
>>>
>>>>> ==== Attachment 0 (0001-mm-damon-paddr-use-do_div-on-i386-for-damon_pa_pageo.patch) ====
>>>>>    From hackermail Thu Jan  1 00:00:00 1970
>>>>> From: SeongJae Park <sj@kernel.org>
>>>>> To: Andrew Morton <akpm@linux-foundation.org>
>>>>> Cc: SeongJae Park <sj@kernel.org>
>>>>> Cc: damon@lists.linux.dev
>>>>> Cc: kernel-team@meta.com
>>>>> Cc: linux-kernel@vger.kernel.org
>>>>> Cc: linux-mm@kvack.org
>>>>> Date: Mon, 25 Aug 2025 07:41:33 -0700
>>>>> Subject: [PATCH 1/3] mm/damon/paddr: use do_div() on i386 for damon_pa_pageout()
>>>>>             return value
>>>>>
>>>>> Otherwise, __udidi3 linking problem happens on certain configs.
>>>>>
>>>>> Reported-by: kernel test robot <lkp@intel.com>
>>>>> Closes: https://lore.kernel.org/oe-kbuild-all/202508241831.EKwdwXZL-lkp@intel.com/
>>>>> Signed-off-by: SeongJae Park <sj@kernel.org>
>>>>> ---
>>>>>     mm/damon/paddr.c | 14 +++++++++++++-
>>>>>     1 file changed, 13 insertions(+), 1 deletion(-)
>>>>>
>>>>> diff --git a/mm/damon/paddr.c b/mm/damon/paddr.c
>>>>> index 5fad2f9a99a0..09c87583af6c 100644
>>>>> --- a/mm/damon/paddr.c
>>>>> +++ b/mm/damon/paddr.c
>>>>> @@ -135,6 +135,18 @@ static bool damon_pa_invalid_damos_folio(struct folio *folio, struct damos *s)
>>>>>     	return false;
>>>>>     }
>>>>>     
>>>>> +/* convert physical address to core-layer address */
>>>>> +static unsigned long damon_pa_core_addr(phys_addr_t pa,
>>>>> +		unsigned long addr_unit)
>>>>> +{
>>>>> +#ifdef __i386__
>>>> Can we use the following condition instead?
>>>>
>>>> #if !defined(CONFIG_64BIT) && defined(CONFIG_PHYS_ADDR_T_64BIT)
>>> To my understanding, this issue happens only on i386, not every 32bit
>>> architectures.  So I think i386 specific condition is better.
>> I understand. However, the aforementioned general condition is essential,
>> and we should propose a new patch to address this. After introducing addr_unit,
>> any 32-bit architecture should support monitoring of 64-bit phys_addr_t.
> The issue is that we cannot divide 64bit values with plain '/' operator on
> "i386", and hence this patch makes it to use do_div() instead of '/' on "i386".
> No such or other problems at supporting 64-bit phys_addr_t is found on other
> 32bit architectures, to my understanding.  My understanding is that at least
> you confirmed that on your arm-based test environment.  So we don't need a new
> patch to my understanding.
>
> Am I missing somthing?

This is because I seem to have made a mistake earlier: I adjusted the local
compilation toolchain. When the __udivdi3 issue mentioned above occurred, it
reminded me of a potential problem. After switching to a completely new environment
for testing, I discovered the __aeabi_uldivmod linking error in arm, which is similar
to the __udivdi3 issue.🙁 To prevent similar environment-related problems in the
future, I suggest adjusting the condition to the following:

#if !defined(CONFIG_64BIT) && defined(CONFIG_PHYS_ADDR_T_64BIT)

Please consider approving this fix.


Best regards,
Quanmin Yan


[...]

Re: [PATCH v2 03/11] mm/damon/paddr: support addr_unit for DAMOS_PAGEOUT

[SeongJae Park]

On Wed, 27 Aug 2025 10:21:41 +0800 Quanmin Yan <yanquanmin1@huawei.com> wrote:

> 
> 在 2025/8/26 22:21, SeongJae Park 写道:
> > On Tue, 26 Aug 2025 12:51:17 +0800 Quanmin Yan <yanquanmin1@huawei.com> wrote:
> >
> >> Hi SJ,
> >>
> >> 在 2025/8/26 11:21, SeongJae Park 写道:
> >>> [...]
> >>>
> >>>>> ==== Attachment 0 (0001-mm-damon-paddr-use-do_div-on-i386-for-damon_pa_pageo.patch) ====
> >>>>>    From hackermail Thu Jan  1 00:00:00 1970
> >>>>> From: SeongJae Park <sj@kernel.org>
> >>>>> To: Andrew Morton <akpm@linux-foundation.org>
> >>>>> Cc: SeongJae Park <sj@kernel.org>
> >>>>> Cc: damon@lists.linux.dev
> >>>>> Cc: kernel-team@meta.com
> >>>>> Cc: linux-kernel@vger.kernel.org
> >>>>> Cc: linux-mm@kvack.org
> >>>>> Date: Mon, 25 Aug 2025 07:41:33 -0700
> >>>>> Subject: [PATCH 1/3] mm/damon/paddr: use do_div() on i386 for damon_pa_pageout()
> >>>>>             return value
> >>>>>
> >>>>> Otherwise, __udidi3 linking problem happens on certain configs.
> >>>>>
> >>>>> Reported-by: kernel test robot <lkp@intel.com>
> >>>>> Closes: https://lore.kernel.org/oe-kbuild-all/202508241831.EKwdwXZL-lkp@intel.com/
> >>>>> Signed-off-by: SeongJae Park <sj@kernel.org>
> >>>>> ---
> >>>>>     mm/damon/paddr.c | 14 +++++++++++++-
> >>>>>     1 file changed, 13 insertions(+), 1 deletion(-)
> >>>>>
> >>>>> diff --git a/mm/damon/paddr.c b/mm/damon/paddr.c
> >>>>> index 5fad2f9a99a0..09c87583af6c 100644
> >>>>> --- a/mm/damon/paddr.c
> >>>>> +++ b/mm/damon/paddr.c
> >>>>> @@ -135,6 +135,18 @@ static bool damon_pa_invalid_damos_folio(struct folio *folio, struct damos *s)
> >>>>>     	return false;
> >>>>>     }
> >>>>>     
> >>>>> +/* convert physical address to core-layer address */
> >>>>> +static unsigned long damon_pa_core_addr(phys_addr_t pa,
> >>>>> +		unsigned long addr_unit)
> >>>>> +{
> >>>>> +#ifdef __i386__
> >>>> Can we use the following condition instead?
> >>>>
> >>>> #if !defined(CONFIG_64BIT) && defined(CONFIG_PHYS_ADDR_T_64BIT)
> >>> To my understanding, this issue happens only on i386, not every 32bit
> >>> architectures.  So I think i386 specific condition is better.
> >> I understand. However, the aforementioned general condition is essential,
> >> and we should propose a new patch to address this. After introducing addr_unit,
> >> any 32-bit architecture should support monitoring of 64-bit phys_addr_t.
> > The issue is that we cannot divide 64bit values with plain '/' operator on
> > "i386", and hence this patch makes it to use do_div() instead of '/' on "i386".
> > No such or other problems at supporting 64-bit phys_addr_t is found on other
> > 32bit architectures, to my understanding.  My understanding is that at least
> > you confirmed that on your arm-based test environment.  So we don't need a new
> > patch to my understanding.
> >
> > Am I missing somthing?
> 
> This is because I seem to have made a mistake earlier: I adjusted the local
> compilation toolchain. When the __udivdi3 issue mentioned above occurred, it
> reminded me of a potential problem. After switching to a completely new environment
> for testing, I discovered the __aeabi_uldivmod linking error in arm, which is similar
> to the __udivdi3 issue.🙁

Thank you for sharing this.  Then I agree the current fixup is insufficient.

Andrew, could you please drop this patch series from mm tree for now?  I will
further discuss with Quanmin about the proper fix and post next version of this
series with the proper fixup.

> To prevent similar environment-related problems in the
> future, I suggest adjusting the condition to the following:
> 
> #if !defined(CONFIG_64BIT) && defined(CONFIG_PHYS_ADDR_T_64BIT)
> 
> Please consider approving this fix.

I'm yet in travel, and I'd like to take more time on thinking about the proper
fix.  Quanmin, could you share more details about your test setups, both for
the compiling success case and failing case?


Thanks,
SJ

[...]

Re: [PATCH v2 03/11] mm/damon/paddr: support addr_unit for DAMOS_PAGEOUT

[Andrew Morton]

On Tue, 26 Aug 2025 19:42:44 -0700 SeongJae Park <sj@kernel.org> wrote:

> Andrew, could you please drop this patch series from mm tree for now? 

Gone.

Re: [PATCH v2 03/11] mm/damon/paddr: support addr_unit for DAMOS_PAGEOUT

[Quanmin Yan]

Hi SJ,

在 2025/8/27 10:42, SeongJae Park 写道:
> On Wed, 27 Aug 2025 10:21:41 +0800 Quanmin Yan <yanquanmin1@huawei.com> wrote:
>
>> 在 2025/8/26 22:21, SeongJae Park 写道:
>>> On Tue, 26 Aug 2025 12:51:17 +0800 Quanmin Yan <yanquanmin1@huawei.com> wrote:
>>>
>>>> Hi SJ,
>>>>
>>>> 在 2025/8/26 11:21, SeongJae Park 写道:
>>>>> [...]
>>>>>
>>>>>>> ==== Attachment 0 (0001-mm-damon-paddr-use-do_div-on-i386-for-damon_pa_pageo.patch) ====
>>>>>>>     From hackermail Thu Jan  1 00:00:00 1970
>>>>>>> From: SeongJae Park <sj@kernel.org>
>>>>>>> To: Andrew Morton <akpm@linux-foundation.org>
>>>>>>> Cc: SeongJae Park <sj@kernel.org>
>>>>>>> Cc: damon@lists.linux.dev
>>>>>>> Cc: kernel-team@meta.com
>>>>>>> Cc: linux-kernel@vger.kernel.org
>>>>>>> Cc: linux-mm@kvack.org
>>>>>>> Date: Mon, 25 Aug 2025 07:41:33 -0700
>>>>>>> Subject: [PATCH 1/3] mm/damon/paddr: use do_div() on i386 for damon_pa_pageout()
>>>>>>>              return value
>>>>>>>
>>>>>>> Otherwise, __udidi3 linking problem happens on certain configs.
>>>>>>>
>>>>>>> Reported-by: kernel test robot <lkp@intel.com>
>>>>>>> Closes: https://lore.kernel.org/oe-kbuild-all/202508241831.EKwdwXZL-lkp@intel.com/
>>>>>>> Signed-off-by: SeongJae Park <sj@kernel.org>
>>>>>>> ---
>>>>>>>      mm/damon/paddr.c | 14 +++++++++++++-
>>>>>>>      1 file changed, 13 insertions(+), 1 deletion(-)
>>>>>>>
>>>>>>> diff --git a/mm/damon/paddr.c b/mm/damon/paddr.c
>>>>>>> index 5fad2f9a99a0..09c87583af6c 100644
>>>>>>> --- a/mm/damon/paddr.c
>>>>>>> +++ b/mm/damon/paddr.c
>>>>>>> @@ -135,6 +135,18 @@ static bool damon_pa_invalid_damos_folio(struct folio *folio, struct damos *s)
>>>>>>>      	return false;
>>>>>>>      }
>>>>>>>      
>>>>>>> +/* convert physical address to core-layer address */
>>>>>>> +static unsigned long damon_pa_core_addr(phys_addr_t pa,
>>>>>>> +		unsigned long addr_unit)
>>>>>>> +{
>>>>>>> +#ifdef __i386__
>>>>>> Can we use the following condition instead?
>>>>>>
>>>>>> #if !defined(CONFIG_64BIT) && defined(CONFIG_PHYS_ADDR_T_64BIT)
>>>>> To my understanding, this issue happens only on i386, not every 32bit
>>>>> architectures.  So I think i386 specific condition is better.
>>>> I understand. However, the aforementioned general condition is essential,
>>>> and we should propose a new patch to address this. After introducing addr_unit,
>>>> any 32-bit architecture should support monitoring of 64-bit phys_addr_t.
>>> The issue is that we cannot divide 64bit values with plain '/' operator on
>>> "i386", and hence this patch makes it to use do_div() instead of '/' on "i386".
>>> No such or other problems at supporting 64-bit phys_addr_t is found on other
>>> 32bit architectures, to my understanding.  My understanding is that at least
>>> you confirmed that on your arm-based test environment.  So we don't need a new
>>> patch to my understanding.
>>>
>>> Am I missing somthing?
>> This is because I seem to have made a mistake earlier: I adjusted the local
>> compilation toolchain. When the __udivdi3 issue mentioned above occurred, it
>> reminded me of a potential problem. After switching to a completely new environment
>> for testing, I discovered the __aeabi_uldivmod linking error in arm, which is similar
>> to the __udivdi3 issue.🙁
> Thank you for sharing this.  Then I agree the current fixup is insufficient.
>
> Andrew, could you please drop this patch series from mm tree for now?  I will
> further discuss with Quanmin about the proper fix and post next version of this
> series with the proper fixup.
>
>> To prevent similar environment-related problems in the
>> future, I suggest adjusting the condition to the following:
>>
>> #if !defined(CONFIG_64BIT) && defined(CONFIG_PHYS_ADDR_T_64BIT)
>>
>> Please consider approving this fix.
> I'm yet in travel, and I'd like to take more time on thinking about the proper
> fix.  Quanmin, could you share more details about your test setups, both for
> the compiling success case and failing case?

Apologies for disturbing you during your travels. Please allow me to explain:

When CONFIG_PHYS_ADDR_T_64BIT is enabled on "i386" [1], the phys_addr_t type
becomes 64-bit, requiring the use of the do_div function. We are in agreement
on this point.

On arm32, if LPAE (which we intend to support in this series) is enabled,
CONFIG_PHYS_ADDR_T_64BIT will also be enabled. In this case, pa / addr_unit
will involve 64-bit division and similarly require the do_div function.
Obviously, such link errors should normally occur under these circumstances.
Unfortunately, the expected anomalies did not manifest in my previous tests.
This may be related to some incorrect adjustments I had made to my local build
environment quite some time ago — though I cannot be entirely certain. That
said, I have since cleaned up the old configurations and ensured the current
environment is clean and normal. For now, we have confirmed the actual problem
and its root cause, shall we focus on fixing it?

In summary, after introducing addr_unit, we expect that any 32-bit architecture
should support monitoring of 64-bit phys_addr_t. Therefore, we can consider the
following adjustment:

#if !defined(CONFIG_64BIT) && defined(CONFIG_PHYS_ADDR_T_64BIT)

Or at least adjust it to:

#if defined(__i386__) || (defined(__arm__) && defined(CONFIG_PHYS_ADDR_T_64BIT))

I have thoroughly re-validated the feature functionality today and confirmed the
correctness of the aforementioned modifications. Therefore, could I kindly ask
you to consider the aforementioned modifications when you have some free time?

[1]https://download.01.org/0day-ci/archive/20250824/202508241831.EKwdwXZL-lkp@intel.com/config

Thanks,
Quanmin Yan

[...]

Re: [PATCH v2 03/11] mm/damon/paddr: support addr_unit for DAMOS_PAGEOUT

[SeongJae Park]

On Wed, 27 Aug 2025 19:37:38 +0800 Quanmin Yan <yanquanmin1@huawei.com> wrote:

> Hi SJ,
> 
> 在 2025/8/27 10:42, SeongJae Park 写道:
> > On Wed, 27 Aug 2025 10:21:41 +0800 Quanmin Yan <yanquanmin1@huawei.com> wrote:
> >
> >> 在 2025/8/26 22:21, SeongJae Park 写道:
> >>> On Tue, 26 Aug 2025 12:51:17 +0800 Quanmin Yan <yanquanmin1@huawei.com> wrote:
> >>>
> >>>> Hi SJ,
> >>>>
> >>>> 在 2025/8/26 11:21, SeongJae Park 写道:
[...]
> >> Please consider approving this fix.
> > I'm yet in travel, and I'd like to take more time on thinking about the proper
> > fix.  Quanmin, could you share more details about your test setups, both for
> > the compiling success case and failing case?
> 
> Apologies for disturbing you during your travels. Please allow me to explain:

No worry, I'm the one who would like to apologize, for delayed response :)
I'm back from the travel, btw.

> 
> When CONFIG_PHYS_ADDR_T_64BIT is enabled on "i386" [1], the phys_addr_t type
> becomes 64-bit, requiring the use of the do_div function. We are in agreement
> on this point.
> 
> On arm32, if LPAE (which we intend to support in this series) is enabled,
> CONFIG_PHYS_ADDR_T_64BIT will also be enabled. In this case, pa / addr_unit
> will involve 64-bit division and similarly require the do_div function.
> Obviously, such link errors should normally occur under these circumstances.
> Unfortunately, the expected anomalies did not manifest in my previous tests.
> This may be related to some incorrect adjustments I had made to my local build
> environment quite some time ago — though I cannot be entirely certain. That
> said, I have since cleaned up the old configurations and ensured the current
> environment is clean and normal. For now, we have confirmed the actual problem
> and its root cause, shall we focus on fixing it?

Thank you for sharing the details.  I wanted to better understand where the
issue happens and not, to clearly understand the root cause and make a proper
fix based on that.  I think we can now focusing on fixing it.

> 
> In summary, after introducing addr_unit, we expect that any 32-bit architecture
> should support monitoring of 64-bit phys_addr_t. Therefore, we can consider the
> following adjustment:
> 
> #if !defined(CONFIG_64BIT) && defined(CONFIG_PHYS_ADDR_T_64BIT)
> 
> Or at least adjust it to:
> 
> #if defined(__i386__) || (defined(__arm__) && defined(CONFIG_PHYS_ADDR_T_64BIT))
> 
> I have thoroughly re-validated the feature functionality today and confirmed the
> correctness of the aforementioned modifications. Therefore, could I kindly ask
> you to consider the aforementioned modifications when you have some free time?

Thank you for the suggestion and testing, Quanmin!

I was thinking making the change for only i386 is right since I was mistakenly
thinking the issue happens only on i386.  Now it is clear I was wrong and we
have at least two cases.  And I agree your suggestion will fix both cases.

But I'm bit concerned i386 and arm might not all the case, so wannt make the
fix more generalized.  My understanding of the problem, which is enlightened
thanks to you, is that not every config supports dividing 64 bit with 32 bit.
And div_u64() is suggested in general for dividing 64 bit with 32 bit.  So,
what about making the if condition more general but specific to the root cause,
like below?

static unsigned long damon_pa_core_addr(
               phys_addr_t pa, unsigned long addr_unit)
{
       /*
        * Use div_u64() for avoiding linking errors related with __udivdi3,
        * __aeabi_uldivmod, or similar problems.  This should also improve the
        * performance optimization (read div_u64() comment for the detail).
        */
       if (sizeof(pa) == 8 && sizeof(addr_unit) == 4)
               return div_u64(pa, addr_unit);
       return pa / addr_unit;
}

Because the sizeof() result can be known at compile time, I think it shouldn't
cause the linking time error, and I confirmed that by passing the i386 test
case that kernel test robot shared.

Could I ask your opinion, Quanmin?  If you think that works, I could post v3 of
this patch series with the above fix.


Thanks,
SJ

[...]

Re: [PATCH v2 03/11] mm/damon/paddr: support addr_unit for DAMOS_PAGEOUT

[Quanmin Yan]

在 2025/8/28 2:07, SeongJae Park 写道:
> On Wed, 27 Aug 2025 19:37:38 +0800 Quanmin Yan <yanquanmin1@huawei.com> wrote:
>
>> Hi SJ,
>>
>> 在 2025/8/27 10:42, SeongJae Park 写道:
>>> On Wed, 27 Aug 2025 10:21:41 +0800 Quanmin Yan <yanquanmin1@huawei.com> wrote:
>>>
>>>> 在 2025/8/26 22:21, SeongJae Park 写道:
>>>>> On Tue, 26 Aug 2025 12:51:17 +0800 Quanmin Yan <yanquanmin1@huawei.com> wrote:
>>>>>
>>>>>> Hi SJ,
>>>>>>
>>>>>> 在 2025/8/26 11:21, SeongJae Park 写道:
> [...]
>>>> Please consider approving this fix.
>>> I'm yet in travel, and I'd like to take more time on thinking about the proper
>>> fix.  Quanmin, could you share more details about your test setups, both for
>>> the compiling success case and failing case?
>> Apologies for disturbing you during your travels. Please allow me to explain:
> No worry, I'm the one who would like to apologize, for delayed response :)
> I'm back from the travel, btw.
>
>> When CONFIG_PHYS_ADDR_T_64BIT is enabled on "i386" [1], the phys_addr_t type
>> becomes 64-bit, requiring the use of the do_div function. We are in agreement
>> on this point.
>>
>> On arm32, if LPAE (which we intend to support in this series) is enabled,
>> CONFIG_PHYS_ADDR_T_64BIT will also be enabled. In this case, pa / addr_unit
>> will involve 64-bit division and similarly require the do_div function.
>> Obviously, such link errors should normally occur under these circumstances.
>> Unfortunately, the expected anomalies did not manifest in my previous tests.
>> This may be related to some incorrect adjustments I had made to my local build
>> environment quite some time ago — though I cannot be entirely certain. That
>> said, I have since cleaned up the old configurations and ensured the current
>> environment is clean and normal. For now, we have confirmed the actual problem
>> and its root cause, shall we focus on fixing it?
> Thank you for sharing the details.  I wanted to better understand where the
> issue happens and not, to clearly understand the root cause and make a proper
> fix based on that.  I think we can now focusing on fixing it.
>
>> In summary, after introducing addr_unit, we expect that any 32-bit architecture
>> should support monitoring of 64-bit phys_addr_t. Therefore, we can consider the
>> following adjustment:
>>
>> #if !defined(CONFIG_64BIT) && defined(CONFIG_PHYS_ADDR_T_64BIT)
>>
>> Or at least adjust it to:
>>
>> #if defined(__i386__) || (defined(__arm__) && defined(CONFIG_PHYS_ADDR_T_64BIT))
>>
>> I have thoroughly re-validated the feature functionality today and confirmed the
>> correctness of the aforementioned modifications. Therefore, could I kindly ask
>> you to consider the aforementioned modifications when you have some free time?
> Thank you for the suggestion and testing, Quanmin!
>
> I was thinking making the change for only i386 is right since I was mistakenly
> thinking the issue happens only on i386.  Now it is clear I was wrong and we
> have at least two cases.  And I agree your suggestion will fix both cases.
>
> But I'm bit concerned i386 and arm might not all the case, so wannt make the
> fix more generalized.  My understanding of the problem, which is enlightened
> thanks to you, is that not every config supports dividing 64 bit with 32 bit.
> And div_u64() is suggested in general for dividing 64 bit with 32 bit.  So,
> what about making the if condition more general but specific to the root cause,
> like below?
>
> static unsigned long damon_pa_core_addr(
>                 phys_addr_t pa, unsigned long addr_unit)
> {
>         /*
>          * Use div_u64() for avoiding linking errors related with __udivdi3,
>          * __aeabi_uldivmod, or similar problems.  This should also improve the
>          * performance optimization (read div_u64() comment for the detail).
>          */
>         if (sizeof(pa) == 8 && sizeof(addr_unit) == 4)
>                 return div_u64(pa, addr_unit);
>         return pa / addr_unit;
> }
>
> Because the sizeof() result can be known at compile time, I think it shouldn't
> cause the linking time error, and I confirmed that by passing the i386 test
> case that kernel test robot shared.
>
> Could I ask your opinion, Quanmin?  If you think that works, I could post v3 of
> this patch series with the above fix.

Great! I believe this approach is better. This modification is more generic
and eliminates the need to deal with those messy configs.

I have also re-validated based on this change, and it is working correctly.

Thanks,
Quanmin Yan

Re: [PATCH v2 03/11] mm/damon/paddr: support addr_unit for DAMOS_PAGEOUT

[SeongJae Park]

On Thu, 28 Aug 2025 09:38:34 +0800 Quanmin Yan <yanquanmin1@huawei.com> wrote:

[...]
> Great! I believe this approach is better. This modification is more generic
> and eliminates the need to deal with those messy configs.
> 
> I have also re-validated based on this change, and it is working correctly.

Thank you for reviewing the code and further testing it!  I will post v3 with
this fix soon, probably tomorrow morning in Pacific Time, unless someone make
a different opinion or I find something I missed by then.


Thanks,
SJ

[...]

[PATCH v2 04/11] mm/damon/paddr: support addr_unit for DAMOS_LRU_[DE]PRIO

[Quanmin Yan]

From: SeongJae Park <sj@kernel.org>

Add support of addr_unit for DAMOS_LRU_PRIO and DAMOS_LRU_DEPRIO action
handling from the DAMOS operation implementation for the physical
address space.

Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Quanmin Yan <yanquanmin1@huawei.com>
Reviewed-by: SeongJae Park <sj@kernel.org>
---
 mm/damon/paddr.c | 29 +++++++++++++++++------------
 1 file changed, 17 insertions(+), 12 deletions(-)

diff --git a/mm/damon/paddr.c b/mm/damon/paddr.c
index 826c2064dbfd..ed71dd0bf80e 100644
--- a/mm/damon/paddr.c
+++ b/mm/damon/paddr.c
@@ -194,14 +194,15 @@ static unsigned long damon_pa_pageout(struct damon_region *r,
 }
 
 static inline unsigned long damon_pa_mark_accessed_or_deactivate(
-		struct damon_region *r, struct damos *s, bool mark_accessed,
+		struct damon_region *r, unsigned long addr_unit,
+		struct damos *s, bool mark_accessed,
 		unsigned long *sz_filter_passed)
 {
-	unsigned long addr, applied = 0;
+	phys_addr_t addr, applied = 0;
 	struct folio *folio;
 
-	addr = r->ar.start;
-	while (addr < r->ar.end) {
+	addr = damon_pa_phys_addr(r->ar.start, addr_unit);
+	while (addr < damon_pa_phys_addr(r->ar.end, addr_unit)) {
 		folio = damon_get_folio(PHYS_PFN(addr));
 		if (damon_pa_invalid_damos_folio(folio, s)) {
 			addr += PAGE_SIZE;
@@ -211,7 +212,7 @@ static inline unsigned long damon_pa_mark_accessed_or_deactivate(
 		if (damos_pa_filter_out(s, folio))
 			goto put_folio;
 		else
-			*sz_filter_passed += folio_size(folio);
+			*sz_filter_passed += folio_size(folio) / addr_unit;
 
 		if (mark_accessed)
 			folio_mark_accessed(folio);
@@ -223,20 +224,22 @@ static inline unsigned long damon_pa_mark_accessed_or_deactivate(
 		folio_put(folio);
 	}
 	s->last_applied = folio;
-	return applied * PAGE_SIZE;
+	return applied * PAGE_SIZE / addr_unit;
 }
 
 static unsigned long damon_pa_mark_accessed(struct damon_region *r,
-	struct damos *s, unsigned long *sz_filter_passed)
+		unsigned long addr_unit, struct damos *s,
+		unsigned long *sz_filter_passed)
 {
-	return damon_pa_mark_accessed_or_deactivate(r, s, true,
+	return damon_pa_mark_accessed_or_deactivate(r, addr_unit, s, true,
 			sz_filter_passed);
 }
 
 static unsigned long damon_pa_deactivate_pages(struct damon_region *r,
-	struct damos *s, unsigned long *sz_filter_passed)
+		unsigned long addr_unit, struct damos *s,
+		unsigned long *sz_filter_passed)
 {
-	return damon_pa_mark_accessed_or_deactivate(r, s, false,
+	return damon_pa_mark_accessed_or_deactivate(r, addr_unit, s, false,
 			sz_filter_passed);
 }
 
@@ -309,9 +312,11 @@ static unsigned long damon_pa_apply_scheme(struct damon_ctx *ctx,
 	case DAMOS_PAGEOUT:
 		return damon_pa_pageout(r, aunit, scheme, sz_filter_passed);
 	case DAMOS_LRU_PRIO:
-		return damon_pa_mark_accessed(r, scheme, sz_filter_passed);
+		return damon_pa_mark_accessed(r, aunit, scheme,
+				sz_filter_passed);
 	case DAMOS_LRU_DEPRIO:
-		return damon_pa_deactivate_pages(r, scheme, sz_filter_passed);
+		return damon_pa_deactivate_pages(r, aunit, scheme,
+				sz_filter_passed);
 	case DAMOS_MIGRATE_HOT:
 	case DAMOS_MIGRATE_COLD:
 		return damon_pa_migrate(r, scheme, sz_filter_passed);
-- 
2.43.0

Re: [PATCH v2 04/11] mm/damon/paddr: support addr_unit for DAMOS_LRU_[DE]PRIO

[SeongJae Park]

On Fri, 22 Aug 2025 17:34:12 +0800 Quanmin Yan <yanquanmin1@huawei.com> wrote:

> From: SeongJae Park <sj@kernel.org>
> 
> Add support of addr_unit for DAMOS_LRU_PRIO and DAMOS_LRU_DEPRIO action
> handling from the DAMOS operation implementation for the physical
> address space.
[...]
> -	return applied * PAGE_SIZE;
> +	return applied * PAGE_SIZE / addr_unit;
>  }

This can cause __udivdi3 linking issue similar to the report [1] from kernel
test robot.  Andrew, could you please add below attaching fixup?

[1] https://lore.kernel.org/oe-kbuild-all/202508241831.EKwdwXZL-lkp@intel.com/


Thanks,
SJ

[...]

==== Attachment 0 (0002-mm-damon-paddr-use-do_div-on-i386-for-damon_pa_de_ac.patch) ====
From hackermail Thu Jan  1 00:00:00 1970
From: SeongJae Park <sj@kernel.org>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: SeongJae Park <sj@kernel.org>
Cc: damon@lists.linux.dev
Cc: kernel-team@meta.com
Cc: linux-kernel@vger.kernel.org
Cc: linux-mm@kvack.org
Date: Mon, 25 Aug 2025 07:45:24 -0700
Subject: [PATCH 2/3] mm/damon/paddr: use do_div() on i386 for
         damon_pa_de_activate() return value

Otherwise, __udivdi3 linking issue happens on certain configs.

Signed-off-by: SeongJae Park <sj@kernel.org>
---
 mm/damon/paddr.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/damon/paddr.c b/mm/damon/paddr.c
index 09c87583af6c..6fb92ecc513d 100644
--- a/mm/damon/paddr.c
+++ b/mm/damon/paddr.c
@@ -236,7 +236,7 @@ static inline unsigned long damon_pa_mark_accessed_or_deactivate(
 		folio_put(folio);
 	}
 	s->last_applied = folio;
-	return applied * PAGE_SIZE / addr_unit;
+	return damon_pa_core_addr(applied * PAGE_SIZE, addr_unit);
 }
 
 static unsigned long damon_pa_mark_accessed(struct damon_region *r,
-- 
2.39.5

Re: [PATCH v2 04/11] mm/damon/paddr: support addr_unit for DAMOS_LRU_[DE]PRIO

[SeongJae Park]

On Mon, 25 Aug 2025 08:13:53 -0700 SeongJae Park <sj@kernel.org> wrote:

> On Fri, 22 Aug 2025 17:34:12 +0800 Quanmin Yan <yanquanmin1@huawei.com> wrote:
> 
> > From: SeongJae Park <sj@kernel.org>
> > 
> > Add support of addr_unit for DAMOS_LRU_PRIO and DAMOS_LRU_DEPRIO action
> > handling from the DAMOS operation implementation for the physical
> > address space.
> [...]
> > -	return applied * PAGE_SIZE;
> > +	return applied * PAGE_SIZE / addr_unit;
> >  }
> 
> This can cause __udivdi3 linking issue similar to the report [1] from kernel
> test robot.  Andrew, could you please add below attaching fixup?
> 
> [1] https://lore.kernel.org/oe-kbuild-all/202508241831.EKwdwXZL-lkp@intel.com/

Hi Andrew, I posted three fixups for the __udivdi3 issue, and I see you picked
two of those in mm tree.  But this one is not yet picked.  Could you please
also add this fixup to mm tree?


Thanks,
SJ

> 
> 
> Thanks,
> SJ
> 
> [...]
> 
> ==== Attachment 0 (0002-mm-damon-paddr-use-do_div-on-i386-for-damon_pa_de_ac.patch) ====
> From hackermail Thu Jan  1 00:00:00 1970
> From: SeongJae Park <sj@kernel.org>
> To: Andrew Morton <akpm@linux-foundation.org>
> Cc: SeongJae Park <sj@kernel.org>
> Cc: damon@lists.linux.dev
> Cc: kernel-team@meta.com
> Cc: linux-kernel@vger.kernel.org
> Cc: linux-mm@kvack.org
> Date: Mon, 25 Aug 2025 07:45:24 -0700
> Subject: [PATCH 2/3] mm/damon/paddr: use do_div() on i386 for
>          damon_pa_de_activate() return value
> 
> Otherwise, __udivdi3 linking issue happens on certain configs.
> 
> Signed-off-by: SeongJae Park <sj@kernel.org>
> ---
>  mm/damon/paddr.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/mm/damon/paddr.c b/mm/damon/paddr.c
> index 09c87583af6c..6fb92ecc513d 100644
> --- a/mm/damon/paddr.c
> +++ b/mm/damon/paddr.c
> @@ -236,7 +236,7 @@ static inline unsigned long damon_pa_mark_accessed_or_deactivate(
>  		folio_put(folio);
>  	}
>  	s->last_applied = folio;
> -	return applied * PAGE_SIZE / addr_unit;
> +	return damon_pa_core_addr(applied * PAGE_SIZE, addr_unit);
>  }
>  
>  static unsigned long damon_pa_mark_accessed(struct damon_region *r,
> -- 
> 2.39.5

[PATCH v2 05/11] mm/damon/paddr: support addr_unit for MIGRATE_{HOT,COLD}

[Quanmin Yan]

From: SeongJae Park <sj@kernel.org>

Add support of addr_unit for DAMOS_MIGRATE_HOT and DAMOS_MIGRATE_COLD
action handling from the DAMOS operation implementation for the physical
address space.

Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Quanmin Yan <yanquanmin1@huawei.com>
Reviewed-by: SeongJae Park <sj@kernel.org>
---
 mm/damon/paddr.c | 15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)

diff --git a/mm/damon/paddr.c b/mm/damon/paddr.c
index ed71dd0bf80e..0305e59818da 100644
--- a/mm/damon/paddr.c
+++ b/mm/damon/paddr.c
@@ -243,15 +243,16 @@ static unsigned long damon_pa_deactivate_pages(struct damon_region *r,
 			sz_filter_passed);
 }
 
-static unsigned long damon_pa_migrate(struct damon_region *r, struct damos *s,
+static unsigned long damon_pa_migrate(struct damon_region *r,
+		unsigned long addr_unit, struct damos *s,
 		unsigned long *sz_filter_passed)
 {
-	unsigned long addr, applied;
+	phys_addr_t addr, applied;
 	LIST_HEAD(folio_list);
 	struct folio *folio;
 
-	addr = r->ar.start;
-	while (addr < r->ar.end) {
+	addr = damon_pa_phys_addr(r->ar.start, addr_unit);
+	while (addr < damon_pa_phys_addr(r->ar.end, addr_unit)) {
 		folio = damon_get_folio(PHYS_PFN(addr));
 		if (damon_pa_invalid_damos_folio(folio, s)) {
 			addr += PAGE_SIZE;
@@ -261,7 +262,7 @@ static unsigned long damon_pa_migrate(struct damon_region *r, struct damos *s,
 		if (damos_pa_filter_out(s, folio))
 			goto put_folio;
 		else
-			*sz_filter_passed += folio_size(folio);
+			*sz_filter_passed += folio_size(folio) / addr_unit;
 
 		if (!folio_isolate_lru(folio))
 			goto put_folio;
@@ -273,7 +274,7 @@ static unsigned long damon_pa_migrate(struct damon_region *r, struct damos *s,
 	applied = damon_migrate_pages(&folio_list, s->target_nid);
 	cond_resched();
 	s->last_applied = folio;
-	return applied * PAGE_SIZE;
+	return applied * PAGE_SIZE / addr_unit;
 }
 
 static unsigned long damon_pa_stat(struct damon_region *r, struct damos *s,
@@ -319,7 +320,7 @@ static unsigned long damon_pa_apply_scheme(struct damon_ctx *ctx,
 				sz_filter_passed);
 	case DAMOS_MIGRATE_HOT:
 	case DAMOS_MIGRATE_COLD:
-		return damon_pa_migrate(r, scheme, sz_filter_passed);
+		return damon_pa_migrate(r, aunit, scheme, sz_filter_passed);
 	case DAMOS_STAT:
 		return damon_pa_stat(r, scheme, sz_filter_passed);
 	default:
-- 
2.43.0

Re: [PATCH v2 05/11] mm/damon/paddr: support addr_unit for MIGRATE_{HOT,COLD}

[SeongJae Park]

On Fri, 22 Aug 2025 17:34:13 +0800 Quanmin Yan <yanquanmin1@huawei.com> wrote:

> From: SeongJae Park <sj@kernel.org>
> 
> Add support of addr_unit for DAMOS_MIGRATE_HOT and DAMOS_MIGRATE_COLD
> action handling from the DAMOS operation implementation for the physical
> address space.
[...]
> -	return applied * PAGE_SIZE;
> +	return applied * PAGE_SIZE / addr_unit;
>  }

This can cause __udivdi3 linking issue similar to a report [1] from kernel test
robot.  Andrew, could you please add below attaching fixup?

[1] https://lore.kernel.org/oe-kbuild-all/202508241831.EKwdwXZL-lkp@intel.com/


Thanks,
SJ

[...]

==== Attachment 0 (0003-mm-damon-paddr-use-do_div-on-i386-for-damon_pa_migra.patch) ====
From hackermail Thu Jan  1 00:00:00 1970
From: SeongJae Park <sj@kernel.org>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: SeongJae Park <sj@kernel.org>
Cc: damon@lists.linux.dev
Cc: kernel-team@meta.com
Cc: linux-kernel@vger.kernel.org
Cc: linux-mm@kvack.org
Date: Mon, 25 Aug 2025 07:46:24 -0700
Subject: [PATCH 3/3] mm/damon/paddr: use do_div() on i386 for damon_pa_migrate()
         return value

Otherwise, __udivdi3 linking issue happens on certain configs.

Signed-off-by: SeongJae Park <sj@kernel.org>
---
 mm/damon/paddr.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/damon/paddr.c b/mm/damon/paddr.c
index 6fb92ecc513d..34248b742a73 100644
--- a/mm/damon/paddr.c
+++ b/mm/damon/paddr.c
@@ -286,7 +286,7 @@ static unsigned long damon_pa_migrate(struct damon_region *r,
 	applied = damon_migrate_pages(&folio_list, s->target_nid);
 	cond_resched();
 	s->last_applied = folio;
-	return applied * PAGE_SIZE / addr_unit;
+	return damon_pa_core_addr(applied * PAGE_SIZE, addr_unit);
 }
 
 static unsigned long damon_pa_stat(struct damon_region *r,
-- 
2.39.5

[PATCH v2 06/11] mm/damon/paddr: support addr_unit for DAMOS_STAT

[Quanmin Yan]

From: SeongJae Park <sj@kernel.org>

Add support of addr_unit for DAMOS_STAT action handling from the DAMOS
operation implementation for the physical address space.

Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Quanmin Yan <yanquanmin1@huawei.com>
Reviewed-by: SeongJae Park <sj@kernel.org>
---
 mm/damon/paddr.c | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/mm/damon/paddr.c b/mm/damon/paddr.c
index 0305e59818da..5fad2f9a99a0 100644
--- a/mm/damon/paddr.c
+++ b/mm/damon/paddr.c
@@ -277,17 +277,18 @@ static unsigned long damon_pa_migrate(struct damon_region *r,
 	return applied * PAGE_SIZE / addr_unit;
 }
 
-static unsigned long damon_pa_stat(struct damon_region *r, struct damos *s,
+static unsigned long damon_pa_stat(struct damon_region *r,
+		unsigned long addr_unit, struct damos *s,
 		unsigned long *sz_filter_passed)
 {
-	unsigned long addr;
+	phys_addr_t addr;
 	struct folio *folio;
 
 	if (!damos_ops_has_filter(s))
 		return 0;
 
-	addr = r->ar.start;
-	while (addr < r->ar.end) {
+	addr = damon_pa_phys_addr(r->ar.start, addr_unit);
+	while (addr < damon_pa_phys_addr(r->ar.end, addr_unit)) {
 		folio = damon_get_folio(PHYS_PFN(addr));
 		if (damon_pa_invalid_damos_folio(folio, s)) {
 			addr += PAGE_SIZE;
@@ -295,7 +296,7 @@ static unsigned long damon_pa_stat(struct damon_region *r, struct damos *s,
 		}
 
 		if (!damos_pa_filter_out(s, folio))
-			*sz_filter_passed += folio_size(folio);
+			*sz_filter_passed += folio_size(folio) / addr_unit;
 		addr += folio_size(folio);
 		folio_put(folio);
 	}
@@ -322,7 +323,7 @@ static unsigned long damon_pa_apply_scheme(struct damon_ctx *ctx,
 	case DAMOS_MIGRATE_COLD:
 		return damon_pa_migrate(r, aunit, scheme, sz_filter_passed);
 	case DAMOS_STAT:
-		return damon_pa_stat(r, scheme, sz_filter_passed);
+		return damon_pa_stat(r, aunit, scheme, sz_filter_passed);
 	default:
 		/* DAMOS actions that not yet supported by 'paddr'. */
 		break;
-- 
2.43.0

[PATCH v2 07/11] mm/damon/sysfs: implement addr_unit file under context dir

[Quanmin Yan]

From: SeongJae Park <sj@kernel.org>

Only DAMON kernel API callers can use addr_unit parameter.  Implement a
sysfs file to let DAMON sysfs ABI users use it.

Additionally, addr_unit must be set to a non-zero value.

Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Quanmin Yan <yanquanmin1@huawei.com>
Reviewed-by: SeongJae Park <sj@kernel.org>
---
 mm/damon/sysfs.c | 33 +++++++++++++++++++++++++++++++++
 1 file changed, 33 insertions(+)

diff --git a/mm/damon/sysfs.c b/mm/damon/sysfs.c
index 6d2b0dab50cb..98bf15d403b2 100644
--- a/mm/damon/sysfs.c
+++ b/mm/damon/sysfs.c
@@ -834,6 +834,7 @@ static const struct damon_sysfs_ops_name damon_sysfs_ops_names[] = {
 struct damon_sysfs_context {
 	struct kobject kobj;
 	enum damon_ops_id ops_id;
+	unsigned long addr_unit;
 	struct damon_sysfs_attrs *attrs;
 	struct damon_sysfs_targets *targets;
 	struct damon_sysfs_schemes *schemes;
@@ -849,6 +850,7 @@ static struct damon_sysfs_context *damon_sysfs_context_alloc(
 		return NULL;
 	context->kobj = (struct kobject){};
 	context->ops_id = ops_id;
+	context->addr_unit = 1;
 	return context;
 }
 
@@ -997,6 +999,32 @@ static ssize_t operations_store(struct kobject *kobj,
 	return -EINVAL;
 }
 
+static ssize_t addr_unit_show(struct kobject *kobj,
+		struct kobj_attribute *attr, char *buf)
+{
+	struct damon_sysfs_context *context = container_of(kobj,
+			struct damon_sysfs_context, kobj);
+
+	return sysfs_emit(buf, "%lu\n", context->addr_unit);
+}
+
+static ssize_t addr_unit_store(struct kobject *kobj,
+		struct kobj_attribute *attr, const char *buf, size_t count)
+{
+	struct damon_sysfs_context *context = container_of(kobj,
+			struct damon_sysfs_context, kobj);
+	unsigned long input_addr_unit;
+	int err = kstrtoul(buf, 0, &input_addr_unit);
+
+	if (err)
+		return err;
+	if (!input_addr_unit)
+		return -EINVAL;
+
+	context->addr_unit = input_addr_unit;
+	return count;
+}
+
 static void damon_sysfs_context_release(struct kobject *kobj)
 {
 	kfree(container_of(kobj, struct damon_sysfs_context, kobj));
@@ -1008,9 +1036,13 @@ static struct kobj_attribute damon_sysfs_context_avail_operations_attr =
 static struct kobj_attribute damon_sysfs_context_operations_attr =
 		__ATTR_RW_MODE(operations, 0600);
 
+static struct kobj_attribute damon_sysfs_context_addr_unit_attr =
+		__ATTR_RW_MODE(addr_unit, 0600);
+
 static struct attribute *damon_sysfs_context_attrs[] = {
 	&damon_sysfs_context_avail_operations_attr.attr,
 	&damon_sysfs_context_operations_attr.attr,
+	&damon_sysfs_context_addr_unit_attr.attr,
 	NULL,
 };
 ATTRIBUTE_GROUPS(damon_sysfs_context);
@@ -1397,6 +1429,7 @@ static int damon_sysfs_apply_inputs(struct damon_ctx *ctx,
 	err = damon_select_ops(ctx, sys_ctx->ops_id);
 	if (err)
 		return err;
+	ctx->addr_unit = sys_ctx->addr_unit;
 	err = damon_sysfs_set_attrs(ctx, sys_ctx->attrs);
 	if (err)
 		return err;
-- 
2.43.0

[PATCH v2 08/11] Docs/mm/damon/design: document 'address unit' parameter

[Quanmin Yan]

From: SeongJae Park <sj@kernel.org>

Add 'addr_unit' parameter description on DAMON design document.

Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Quanmin Yan <yanquanmin1@huawei.com>
Reviewed-by: SeongJae Park <sj@kernel.org>
---
 Documentation/mm/damon/design.rst | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/Documentation/mm/damon/design.rst b/Documentation/mm/damon/design.rst
index 2f6ba5c7f4c7..d9d5baa1ec87 100644
--- a/Documentation/mm/damon/design.rst
+++ b/Documentation/mm/damon/design.rst
@@ -67,7 +67,7 @@ processes, NUMA nodes, files, and backing memory devices would be supportable.
 Also, if some architectures or devices support special optimized access check
 features, those will be easily configurable.
 
-DAMON currently provides below three operation sets.  Below two subsections
+DAMON currently provides below three operation sets.  Below three subsections
 describe how those work.
 
  - vaddr: Monitor virtual address spaces of specific processes
@@ -135,6 +135,18 @@ the interference is the responsibility of sysadmins.  However, it solves the
 conflict with the reclaim logic using ``PG_idle`` and ``PG_young`` page flags,
 as Idle page tracking does.
 
+Address Unit
+------------
+
+DAMON core layer uses ``unsinged long`` type for monitoring target address
+ranges.  In some cases, the address space for a given operations set could be
+too large to be handled with the type.  ARM (32-bit) with large physical
+address extension is an example.  For such cases, a per-operations set
+parameter called ``address unit`` is provided.  It represents the scale factor
+that need to be multiplied to the core layer's address for calculating real
+address on the given address space.  Support of ``address unit`` parameter is
+up to each operations set implementation.  ``paddr`` is the only operations set
+implementation that supports the parameter.
 
 .. _damon_core_logic:
 
-- 
2.43.0

[PATCH v2 09/11] Docs/admin-guide/mm/damon/usage: document addr_unit file

[Quanmin Yan]

From: SeongJae Park <sj@kernel.org>

Document addr_unit DAMON sysfs file on DAMON usage document.

Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Quanmin Yan <yanquanmin1@huawei.com>
Reviewed-by: SeongJae Park <sj@kernel.org>
---
 Documentation/admin-guide/mm/damon/usage.rst | 11 +++++++----
 Documentation/mm/damon/design.rst            |  2 ++
 2 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/Documentation/admin-guide/mm/damon/usage.rst b/Documentation/admin-guide/mm/damon/usage.rst
index ff3a2dda1f02..2cae60b6f3ca 100644
--- a/Documentation/admin-guide/mm/damon/usage.rst
+++ b/Documentation/admin-guide/mm/damon/usage.rst
@@ -61,7 +61,7 @@ comma (",").
     │ :ref:`kdamonds <sysfs_kdamonds>`/nr_kdamonds
     │ │ :ref:`0 <sysfs_kdamond>`/state,pid,refresh_ms
     │ │ │ :ref:`contexts <sysfs_contexts>`/nr_contexts
-    │ │ │ │ :ref:`0 <sysfs_context>`/avail_operations,operations
+    │ │ │ │ :ref:`0 <sysfs_context>`/avail_operations,operations,addr_unit
     │ │ │ │ │ :ref:`monitoring_attrs <sysfs_monitoring_attrs>`/
     │ │ │ │ │ │ intervals/sample_us,aggr_us,update_us
     │ │ │ │ │ │ │ intervals_goal/access_bp,aggrs,min_sample_us,max_sample_us
@@ -188,9 +188,9 @@ details).  At the moment, only one context per kdamond is supported, so only
 contexts/<N>/
 -------------
 
-In each context directory, two files (``avail_operations`` and ``operations``)
-and three directories (``monitoring_attrs``, ``targets``, and ``schemes``)
-exist.
+In each context directory, three files (``avail_operations``, ``operations``
+and ``addr_unit``) and three directories (``monitoring_attrs``, ``targets``,
+and ``schemes``) exist.
 
 DAMON supports multiple types of :ref:`monitoring operations
 <damon_design_configurable_operations_set>`, including those for virtual address
@@ -205,6 +205,9 @@ You can set and get what type of monitoring operations DAMON will use for the
 context by writing one of the keywords listed in ``avail_operations`` file and
 reading from the ``operations`` file.
 
+``addr_unit`` file is for setting and getting the :ref:`address unit
+<damon_design_addr_unit>` parameter of the operations set.
+
 .. _sysfs_monitoring_attrs:
 
 contexts/<N>/monitoring_attrs/
diff --git a/Documentation/mm/damon/design.rst b/Documentation/mm/damon/design.rst
index d9d5baa1ec87..80354f4f42ba 100644
--- a/Documentation/mm/damon/design.rst
+++ b/Documentation/mm/damon/design.rst
@@ -135,6 +135,8 @@ the interference is the responsibility of sysadmins.  However, it solves the
 conflict with the reclaim logic using ``PG_idle`` and ``PG_young`` page flags,
 as Idle page tracking does.
 
+.. _damon_design_addr_unit:
+
 Address Unit
 ------------
 
-- 
2.43.0

[PATCH v2 10/11] Docs/ABI/damon: document addr_unit file

[Quanmin Yan]

From: SeongJae Park <sj@kernel.org>

Document addr_unit DAMON sysfs file on DAMON ABI document.

Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Quanmin Yan <yanquanmin1@huawei.com>
Reviewed-by: SeongJae Park <sj@kernel.org>
---
 Documentation/ABI/testing/sysfs-kernel-mm-damon | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/Documentation/ABI/testing/sysfs-kernel-mm-damon b/Documentation/ABI/testing/sysfs-kernel-mm-damon
index 6791d879759e..b6b71db36ca7 100644
--- a/Documentation/ABI/testing/sysfs-kernel-mm-damon
+++ b/Documentation/ABI/testing/sysfs-kernel-mm-damon
@@ -77,6 +77,13 @@ Description:	Writing a keyword for a monitoring operations set ('vaddr' for
 		Note that only the operations sets that listed in
 		'avail_operations' file are valid inputs.
 
+What:		/sys/kernel/mm/damon/admin/kdamonds/<K>/contexts/<C>/addr_unit
+Date:		Aug 2025
+Contact:	SeongJae Park <sj@kernel.org>
+Description:	Writing an integer to this file sets the 'address unit'
+		parameter of the given operations set of the context.  Reading
+		the file returns the last-written 'address unit' value.
+
 What:		/sys/kernel/mm/damon/admin/kdamonds/<K>/contexts/<C>/monitoring_attrs/intervals/sample_us
 Date:		Mar 2022
 Contact:	SeongJae Park <sj@kernel.org>
-- 
2.43.0

[PATCH v2 11/11] mm/damon: add damon_ctx->min_sz_region

[Quanmin Yan]

Adopting addr_unit would make DAMON_MINREGION 'addr_unit * 4096'
bytes and cause data alignment issues[1].

Add damon_ctx->min_sz_region to change DAMON_MIN_REGION from a global
macro value to per-context variable.

[1] https://lore.kernel.org/all/527714dd-0e33-43ab-bbbd-d89670ba79e7@huawei.com

Signed-off-by: Quanmin Yan <yanquanmin1@huawei.com>
---
 include/linux/damon.h        |  4 ++-
 mm/damon/core.c              | 67 ++++++++++++++++++++----------------
 mm/damon/sysfs.c             |  8 +++--
 mm/damon/tests/core-kunit.h  | 21 ++++++-----
 mm/damon/tests/vaddr-kunit.h |  2 +-
 mm/damon/vaddr.c             |  2 +-
 6 files changed, 61 insertions(+), 43 deletions(-)

diff --git a/include/linux/damon.h b/include/linux/damon.h
index 6fa52f7495d9..ec8716292c09 100644
--- a/include/linux/damon.h
+++ b/include/linux/damon.h
@@ -747,6 +747,7 @@ struct damon_attrs {
  *
  * @ops:	Set of monitoring operations for given use cases.
  * @addr_unit:	Scale factor for core to ops address conversion.
+ * @min_sz_region:		Minimum region size.
  * @adaptive_targets:	Head of monitoring targets (&damon_target) list.
  * @schemes:		Head of schemes (&damos) list.
  */
@@ -789,6 +790,7 @@ struct damon_ctx {
 
 	struct damon_operations ops;
 	unsigned long addr_unit;
+	unsigned long min_sz_region;
 
 	struct list_head adaptive_targets;
 	struct list_head schemes;
@@ -877,7 +879,7 @@ static inline void damon_insert_region(struct damon_region *r,
 void damon_add_region(struct damon_region *r, struct damon_target *t);
 void damon_destroy_region(struct damon_region *r, struct damon_target *t);
 int damon_set_regions(struct damon_target *t, struct damon_addr_range *ranges,
-		unsigned int nr_ranges);
+		unsigned int nr_ranges, unsigned long min_sz_region);
 void damon_update_region_access_rate(struct damon_region *r, bool accessed,
 		struct damon_attrs *attrs);
 
diff --git a/mm/damon/core.c b/mm/damon/core.c
index 8f8aa84953ac..7c332be4f291 100644
--- a/mm/damon/core.c
+++ b/mm/damon/core.c
@@ -201,6 +201,7 @@ static int damon_fill_regions_holes(struct damon_region *first,
  * @t:		the given target.
  * @ranges:	array of new monitoring target ranges.
  * @nr_ranges:	length of @ranges.
+ * @min_sz_region:	minimum region size.
  *
  * This function adds new regions to, or modify existing regions of a
  * monitoring target to fit in specific ranges.
@@ -208,7 +209,7 @@ static int damon_fill_regions_holes(struct damon_region *first,
  * Return: 0 if success, or negative error code otherwise.
  */
 int damon_set_regions(struct damon_target *t, struct damon_addr_range *ranges,
-		unsigned int nr_ranges)
+		unsigned int nr_ranges, unsigned long min_sz_region)
 {
 	struct damon_region *r, *next;
 	unsigned int i;
@@ -245,16 +246,16 @@ int damon_set_regions(struct damon_target *t, struct damon_addr_range *ranges,
 			/* no region intersects with this range */
 			newr = damon_new_region(
 					ALIGN_DOWN(range->start,
-						DAMON_MIN_REGION),
-					ALIGN(range->end, DAMON_MIN_REGION));
+						min_sz_region),
+					ALIGN(range->end, min_sz_region));
 			if (!newr)
 				return -ENOMEM;
 			damon_insert_region(newr, damon_prev_region(r), r, t);
 		} else {
 			/* resize intersecting regions to fit in this range */
 			first->ar.start = ALIGN_DOWN(range->start,
-					DAMON_MIN_REGION);
-			last->ar.end = ALIGN(range->end, DAMON_MIN_REGION);
+					min_sz_region);
+			last->ar.end = ALIGN(range->end, min_sz_region);
 
 			/* fill possible holes in the range */
 			err = damon_fill_regions_holes(first, last, t);
@@ -545,6 +546,7 @@ struct damon_ctx *damon_new_ctx(void)
 	ctx->attrs.max_nr_regions = 1000;
 
 	ctx->addr_unit = 1;
+	ctx->min_sz_region = DAMON_MIN_REGION;
 
 	INIT_LIST_HEAD(&ctx->adaptive_targets);
 	INIT_LIST_HEAD(&ctx->schemes);
@@ -1127,8 +1129,8 @@ static struct damon_target *damon_nth_target(int n, struct damon_ctx *ctx)
  *
  * If @src has no region, @dst keeps current regions.
  */
-static int damon_commit_target_regions(
-		struct damon_target *dst, struct damon_target *src)
+static int damon_commit_target_regions(struct damon_target *dst,
+		struct damon_target *src, unsigned long src_min_sz_region)
 {
 	struct damon_region *src_region;
 	struct damon_addr_range *ranges;
@@ -1145,18 +1147,19 @@ static int damon_commit_target_regions(
 	i = 0;
 	damon_for_each_region(src_region, src)
 		ranges[i++] = src_region->ar;
-	err = damon_set_regions(dst, ranges, i);
+	err = damon_set_regions(dst, ranges, i, src_min_sz_region);
 	kfree(ranges);
 	return err;
 }
 
 static int damon_commit_target(
 		struct damon_target *dst, bool dst_has_pid,
-		struct damon_target *src, bool src_has_pid)
+		struct damon_target *src, bool src_has_pid,
+		unsigned long src_min_sz_region)
 {
 	int err;
 
-	err = damon_commit_target_regions(dst, src);
+	err = damon_commit_target_regions(dst, src, src_min_sz_region);
 	if (err)
 		return err;
 	if (dst_has_pid)
@@ -1178,7 +1181,8 @@ static int damon_commit_targets(
 		if (src_target) {
 			err = damon_commit_target(
 					dst_target, damon_target_has_pid(dst),
-					src_target, damon_target_has_pid(src));
+					src_target, damon_target_has_pid(src),
+					src->min_sz_region);
 			if (err)
 				return err;
 		} else {
@@ -1201,7 +1205,8 @@ static int damon_commit_targets(
 		if (!new_target)
 			return -ENOMEM;
 		err = damon_commit_target(new_target, false,
-				src_target, damon_target_has_pid(src));
+				src_target, damon_target_has_pid(src),
+				src->min_sz_region);
 		if (err) {
 			damon_destroy_target(new_target, NULL);
 			return err;
@@ -1248,6 +1253,7 @@ int damon_commit_ctx(struct damon_ctx *dst, struct damon_ctx *src)
 	}
 	dst->ops = src->ops;
 	dst->addr_unit = src->addr_unit;
+	dst->min_sz_region = src->min_sz_region;
 
 	return 0;
 }
@@ -1280,8 +1286,8 @@ static unsigned long damon_region_sz_limit(struct damon_ctx *ctx)
 
 	if (ctx->attrs.min_nr_regions)
 		sz /= ctx->attrs.min_nr_regions;
-	if (sz < DAMON_MIN_REGION)
-		sz = DAMON_MIN_REGION;
+	if (sz < ctx->min_sz_region)
+		sz = ctx->min_sz_region;
 
 	return sz;
 }
@@ -1625,6 +1631,7 @@ static bool damos_valid_target(struct damon_ctx *c, struct damon_target *t,
  * @t:	The target of the region.
  * @rp:	The pointer to the region.
  * @s:	The scheme to be applied.
+ * @min_sz_region:	minimum region size.
  *
  * If a quota of a scheme has exceeded in a quota charge window, the scheme's
  * action would applied to only a part of the target access pattern fulfilling
@@ -1642,7 +1649,7 @@ static bool damos_valid_target(struct damon_ctx *c, struct damon_target *t,
  * Return: true if the region should be entirely skipped, false otherwise.
  */
 static bool damos_skip_charged_region(struct damon_target *t,
-		struct damon_region **rp, struct damos *s)
+		struct damon_region **rp, struct damos *s, unsigned long min_sz_region)
 {
 	struct damon_region *r = *rp;
 	struct damos_quota *quota = &s->quota;
@@ -1664,11 +1671,11 @@ static bool damos_skip_charged_region(struct damon_target *t,
 		if (quota->charge_addr_from && r->ar.start <
 				quota->charge_addr_from) {
 			sz_to_skip = ALIGN_DOWN(quota->charge_addr_from -
-					r->ar.start, DAMON_MIN_REGION);
+					r->ar.start, min_sz_region);
 			if (!sz_to_skip) {
-				if (damon_sz_region(r) <= DAMON_MIN_REGION)
+				if (damon_sz_region(r) <= min_sz_region)
 					return true;
-				sz_to_skip = DAMON_MIN_REGION;
+				sz_to_skip = min_sz_region;
 			}
 			damon_split_region_at(t, r, sz_to_skip);
 			r = damon_next_region(r);
@@ -1693,7 +1700,8 @@ static void damos_update_stat(struct damos *s,
 }
 
 static bool damos_filter_match(struct damon_ctx *ctx, struct damon_target *t,
-		struct damon_region *r, struct damos_filter *filter)
+		struct damon_region *r, struct damos_filter *filter,
+		unsigned long min_sz_region)
 {
 	bool matched = false;
 	struct damon_target *ti;
@@ -1710,8 +1718,8 @@ static bool damos_filter_match(struct damon_ctx *ctx, struct damon_target *t,
 		matched = target_idx == filter->target_idx;
 		break;
 	case DAMOS_FILTER_TYPE_ADDR:
-		start = ALIGN_DOWN(filter->addr_range.start, DAMON_MIN_REGION);
-		end = ALIGN_DOWN(filter->addr_range.end, DAMON_MIN_REGION);
+		start = ALIGN_DOWN(filter->addr_range.start, min_sz_region);
+		end = ALIGN_DOWN(filter->addr_range.end, min_sz_region);
 
 		/* inside the range */
 		if (start <= r->ar.start && r->ar.end <= end) {
@@ -1747,7 +1755,7 @@ static bool damos_filter_out(struct damon_ctx *ctx, struct damon_target *t,
 
 	s->core_filters_allowed = false;
 	damos_for_each_filter(filter, s) {
-		if (damos_filter_match(ctx, t, r, filter)) {
+		if (damos_filter_match(ctx, t, r, filter, ctx->min_sz_region)) {
 			if (filter->allow)
 				s->core_filters_allowed = true;
 			return !filter->allow;
@@ -1882,7 +1890,7 @@ static void damos_apply_scheme(struct damon_ctx *c, struct damon_target *t,
 	if (c->ops.apply_scheme) {
 		if (quota->esz && quota->charged_sz + sz > quota->esz) {
 			sz = ALIGN_DOWN(quota->esz - quota->charged_sz,
-					DAMON_MIN_REGION);
+					c->min_sz_region);
 			if (!sz)
 				goto update_stat;
 			damon_split_region_at(t, r, sz);
@@ -1930,7 +1938,7 @@ static void damon_do_apply_schemes(struct damon_ctx *c,
 		if (quota->esz && quota->charged_sz >= quota->esz)
 			continue;
 
-		if (damos_skip_charged_region(t, &r, s))
+		if (damos_skip_charged_region(t, &r, s, c->min_sz_region))
 			continue;
 
 		if (!damos_valid_target(c, t, r, s))
@@ -2324,7 +2332,8 @@ static void damon_split_region_at(struct damon_target *t,
 }
 
 /* Split every region in the given target into 'nr_subs' regions */
-static void damon_split_regions_of(struct damon_target *t, int nr_subs)
+static void damon_split_regions_of(struct damon_target *t, int nr_subs,
+				  unsigned long min_sz_region)
 {
 	struct damon_region *r, *next;
 	unsigned long sz_region, sz_sub = 0;
@@ -2334,13 +2343,13 @@ static void damon_split_regions_of(struct damon_target *t, int nr_subs)
 		sz_region = damon_sz_region(r);
 
 		for (i = 0; i < nr_subs - 1 &&
-				sz_region > 2 * DAMON_MIN_REGION; i++) {
+				sz_region > 2 * min_sz_region; i++) {
 			/*
 			 * Randomly select size of left sub-region to be at
 			 * least 10 percent and at most 90% of original region
 			 */
 			sz_sub = ALIGN_DOWN(damon_rand(1, 10) *
-					sz_region / 10, DAMON_MIN_REGION);
+					sz_region / 10, min_sz_region);
 			/* Do not allow blank region */
 			if (sz_sub == 0 || sz_sub >= sz_region)
 				continue;
@@ -2380,7 +2389,7 @@ static void kdamond_split_regions(struct damon_ctx *ctx)
 		nr_subregions = 3;
 
 	damon_for_each_target(t, ctx)
-		damon_split_regions_of(t, nr_subregions);
+		damon_split_regions_of(t, nr_subregions, ctx->min_sz_region);
 
 	last_nr_regions = nr_regions;
 }
@@ -2769,7 +2778,7 @@ 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);
+	return damon_set_regions(t, &addr_range, 1, DAMON_MIN_REGION);
 }
 
 /*
diff --git a/mm/damon/sysfs.c b/mm/damon/sysfs.c
index 98bf15d403b2..0ed404c89f80 100644
--- a/mm/damon/sysfs.c
+++ b/mm/damon/sysfs.c
@@ -1329,7 +1329,8 @@ static int damon_sysfs_set_attrs(struct damon_ctx *ctx,
 }
 
 static int damon_sysfs_set_regions(struct damon_target *t,
-		struct damon_sysfs_regions *sysfs_regions)
+		struct damon_sysfs_regions *sysfs_regions,
+		unsigned long min_sz_region)
 {
 	struct damon_addr_range *ranges = kmalloc_array(sysfs_regions->nr,
 			sizeof(*ranges), GFP_KERNEL | __GFP_NOWARN);
@@ -1351,7 +1352,7 @@ static int damon_sysfs_set_regions(struct damon_target *t,
 		if (ranges[i - 1].end > ranges[i].start)
 			goto out;
 	}
-	err = damon_set_regions(t, ranges, sysfs_regions->nr);
+	err = damon_set_regions(t, ranges, sysfs_regions->nr, min_sz_region);
 out:
 	kfree(ranges);
 	return err;
@@ -1372,7 +1373,7 @@ static int damon_sysfs_add_target(struct damon_sysfs_target *sys_target,
 			/* caller will destroy targets */
 			return -EINVAL;
 	}
-	return damon_sysfs_set_regions(t, sys_target->regions);
+	return damon_sysfs_set_regions(t, sys_target->regions, ctx->min_sz_region);
 }
 
 static int damon_sysfs_add_targets(struct damon_ctx *ctx,
@@ -1430,6 +1431,7 @@ static int damon_sysfs_apply_inputs(struct damon_ctx *ctx,
 	if (err)
 		return err;
 	ctx->addr_unit = sys_ctx->addr_unit;
+	ctx->min_sz_region = max(DAMON_MIN_REGION / sys_ctx->addr_unit, 1);
 	err = damon_sysfs_set_attrs(ctx, sys_ctx->attrs);
 	if (err)
 		return err;
diff --git a/mm/damon/tests/core-kunit.h b/mm/damon/tests/core-kunit.h
index 5f5dc9db2e90..51369e35298b 100644
--- a/mm/damon/tests/core-kunit.h
+++ b/mm/damon/tests/core-kunit.h
@@ -230,14 +230,14 @@ static void damon_test_split_regions_of(struct kunit *test)
 	t = damon_new_target();
 	r = damon_new_region(0, 22);
 	damon_add_region(r, t);
-	damon_split_regions_of(t, 2);
+	damon_split_regions_of(t, 2, DAMON_MIN_REGION);
 	KUNIT_EXPECT_LE(test, damon_nr_regions(t), 2u);
 	damon_free_target(t);
 
 	t = damon_new_target();
 	r = damon_new_region(0, 220);
 	damon_add_region(r, t);
-	damon_split_regions_of(t, 4);
+	damon_split_regions_of(t, 4, DAMON_MIN_REGION);
 	KUNIT_EXPECT_LE(test, damon_nr_regions(t), 4u);
 	damon_free_target(t);
 	damon_destroy_ctx(c);
@@ -303,7 +303,7 @@ static void damon_test_set_regions(struct kunit *test)
 
 	damon_add_region(r1, t);
 	damon_add_region(r2, t);
-	damon_set_regions(t, &range, 1);
+	damon_set_regions(t, &range, 1, DAMON_MIN_REGION);
 
 	KUNIT_EXPECT_EQ(test, damon_nr_regions(t), 3);
 	damon_for_each_region(r, t) {
@@ -450,25 +450,29 @@ static void damos_test_filter_out(struct kunit *test)
 	damon_add_region(r, t);
 
 	/* region in the range */
-	KUNIT_EXPECT_TRUE(test, damos_filter_match(NULL, t, r, f));
+	KUNIT_EXPECT_TRUE(test,
+			damos_filter_match(NULL, t, r, f, DAMON_MIN_REGION));
 	KUNIT_EXPECT_EQ(test, damon_nr_regions(t), 1);
 
 	/* region before the range */
 	r->ar.start = DAMON_MIN_REGION * 1;
 	r->ar.end = DAMON_MIN_REGION * 2;
-	KUNIT_EXPECT_FALSE(test, damos_filter_match(NULL, t, r, f));
+	KUNIT_EXPECT_FALSE(test,
+			damos_filter_match(NULL, t, r, f, DAMON_MIN_REGION));
 	KUNIT_EXPECT_EQ(test, damon_nr_regions(t), 1);
 
 	/* region after the range */
 	r->ar.start = DAMON_MIN_REGION * 6;
 	r->ar.end = DAMON_MIN_REGION * 8;
-	KUNIT_EXPECT_FALSE(test, damos_filter_match(NULL, t, r, f));
+	KUNIT_EXPECT_FALSE(test,
+			damos_filter_match(NULL, t, r, f, DAMON_MIN_REGION));
 	KUNIT_EXPECT_EQ(test, damon_nr_regions(t), 1);
 
 	/* region started before the range */
 	r->ar.start = DAMON_MIN_REGION * 1;
 	r->ar.end = DAMON_MIN_REGION * 4;
-	KUNIT_EXPECT_FALSE(test, damos_filter_match(NULL, t, r, f));
+	KUNIT_EXPECT_FALSE(test,
+			damos_filter_match(NULL, t, r, f, DAMON_MIN_REGION));
 	/* filter should have split the region */
 	KUNIT_EXPECT_EQ(test, r->ar.start, DAMON_MIN_REGION * 1);
 	KUNIT_EXPECT_EQ(test, r->ar.end, DAMON_MIN_REGION * 2);
@@ -481,7 +485,8 @@ static void damos_test_filter_out(struct kunit *test)
 	/* region started in the range */
 	r->ar.start = DAMON_MIN_REGION * 2;
 	r->ar.end = DAMON_MIN_REGION * 8;
-	KUNIT_EXPECT_TRUE(test, damos_filter_match(NULL, t, r, f));
+	KUNIT_EXPECT_TRUE(test,
+			damos_filter_match(NULL, t, r, f, DAMON_MIN_REGION));
 	/* filter should have split the region */
 	KUNIT_EXPECT_EQ(test, r->ar.start, DAMON_MIN_REGION * 2);
 	KUNIT_EXPECT_EQ(test, r->ar.end, DAMON_MIN_REGION * 6);
diff --git a/mm/damon/tests/vaddr-kunit.h b/mm/damon/tests/vaddr-kunit.h
index d2b37ccf2cc0..fce38dd53cf8 100644
--- a/mm/damon/tests/vaddr-kunit.h
+++ b/mm/damon/tests/vaddr-kunit.h
@@ -141,7 +141,7 @@ static void damon_do_test_apply_three_regions(struct kunit *test,
 		damon_add_region(r, t);
 	}
 
-	damon_set_regions(t, three_regions, 3);
+	damon_set_regions(t, three_regions, 3, DAMON_MIN_REGION);
 
 	for (i = 0; i < nr_expected / 2; i++) {
 		r = __nth_region_of(t, i);
diff --git a/mm/damon/vaddr.c b/mm/damon/vaddr.c
index 66ef9869eafe..8c048f9b129e 100644
--- a/mm/damon/vaddr.c
+++ b/mm/damon/vaddr.c
@@ -299,7 +299,7 @@ static void damon_va_update(struct damon_ctx *ctx)
 	damon_for_each_target(t, ctx) {
 		if (damon_va_three_regions(t, three_regions))
 			continue;
-		damon_set_regions(t, three_regions, 3);
+		damon_set_regions(t, three_regions, 3, DAMON_MIN_REGION);
 	}
 }
 
-- 
2.43.0

Re: [PATCH v2 11/11] mm/damon: add damon_ctx->min_sz_region

[SeongJae Park]

On Fri, 22 Aug 2025 17:34:19 +0800 Quanmin Yan <yanquanmin1@huawei.com> wrote:

> Adopting addr_unit would make DAMON_MINREGION 'addr_unit * 4096'
> bytes and cause data alignment issues[1].
> 
> Add damon_ctx->min_sz_region to change DAMON_MIN_REGION from a global
> macro value to per-context variable.
> 
> [1] https://lore.kernel.org/all/527714dd-0e33-43ab-bbbd-d89670ba79e7@huawei.com
> 
> Signed-off-by: Quanmin Yan <yanquanmin1@huawei.com>

Reviewed-by: SeongJae Park <sj@kernel.org>


Thanks,
SJ

[...]

Re: [PATCH v2 00/11] mm/damon: support ARM32 with LPAE

[SeongJae Park]

On Fri, 22 Aug 2025 17:34:08 +0800 Quanmin Yan <yanquanmin1@huawei.com> wrote:

> Previously, DAMON's physical address space monitoring only supported
> memory ranges below 4GB on LPAE-enabled systems. This was due to
> the use of 'unsigned long' in 'struct damon_addr_range', which is
> 32-bit on ARM32 even with LPAE enabled[1].
> 
> To add DAMON support for ARM32 with LPAE enabled, a new core layer
> parameter called 'addr_unit' was introduced[2]. Operations set layer
> can translate a core layer address to the real address by multiplying
> the parameter value to the core layer address. Support of the parameter
> is up to each operations layer implementation, though. For example,
> operations set implementations for virtual address space can simply
> ignore the parameter. Add the support on paddr, which is the DAMON
> operations set implementation for the physical address space, as we have
> a clear use case for that.
> 
> [1]https://lore.kernel.org/all/20250408075553.959388-1-zuoze1@huawei.com/
> [2]https://lore.kernel.org/all/20250416042551.158131-1-sj@kernel.org/
> 
> Changes from v1
> (https://lore.kernel.org/all/20250821105159.2503894-1-yanquanmin1@huawei.com/)
> - Set dst->min_sz_region as src->min_sz_region in damon_commit_ctx().
> - Fixed the incorrect 'min_region' in the commit message.

Thank you for continuing this work, Quanmin!  Now the entire series looks good
to me :)


Thanks,
SJ

[...]