linux-kernel - Re: [PATCH v2 03/11] mm/damon/paddr: support addr_unit for DAMOS

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Message-Id: <20250825151205.36288-1-sj@kernel.org>
Date: Mon, 25 Aug 2025 08:12:05 -0700
From: SeongJae Park <sj@...nel.org>
To: Quanmin Yan <yanquanmin1@...wei.com>
Cc: SeongJae Park <sj@...nel.org>,
	akpm@...ux-foundation.org,
	damon@...ts.linux.dev,
	linux-kernel@...r.kernel.org,
	linux-mm@...ck.org,
	wangkefeng.wang@...wei.com,
	zuoze1@...wei.com,
	kernel-team@...a.com,
	kernel test robot <lkp@...el.com>
Subject: Re: [PATCH v2 03/11] mm/damon/paddr: support addr_unit for DAMOS_PAGEOUT

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

> From: SeongJae Park <sj@...nel.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@...nel.org>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: SeongJae Park <sj@...nel.org>
Cc: damon@...ts.linux.dev
Cc: kernel-team@...a.com
Cc: linux-kernel@...r.kernel.org
Cc: linux-mm@...ck.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@...el.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202508241831.EKwdwXZL-lkp@intel.com/
Signed-off-by: SeongJae Park <sj@...nel.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