linux-kernel - Re: [PATCH v2 14/19] mm, swap: sanitize swap entry management workflow

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Message-ID: <CAMgjq7BkVvhsCzk2r53159hDoZ+b+AvP1iUTBHA9zvb+SJFg=Q@mail.gmail.com>
Date: Mon, 17 Nov 2025 21:05:35 +0800
From: Kairui Song <ryncsn@...il.com>
To: linux-mm@...ck.org
Cc: kernel test robot <lkp@...el.com>, llvm@...ts.linux.dev, oe-kbuild-all@...ts.linux.dev, 
	Andrew Morton <akpm@...ux-foundation.org>, Baoquan He <bhe@...hat.com>, 
	Barry Song <baohua@...nel.org>, Chris Li <chrisl@...nel.org>, Nhat Pham <nphamcs@...il.com>, 
	Yosry Ahmed <yosry.ahmed@...ux.dev>, David Hildenbrand <david@...nel.org>, 
	Johannes Weiner <hannes@...xchg.org>, Youngjun Park <youngjun.park@....com>, 
	Hugh Dickins <hughd@...gle.com>, Baolin Wang <baolin.wang@...ux.alibaba.com>, 
	Ying Huang <ying.huang@...ux.alibaba.com>, Kemeng Shi <shikemeng@...weicloud.com>, 
	Lorenzo Stoakes <lorenzo.stoakes@...cle.com>, 
	"Matthew Wilcox (Oracle)" <willy@...radead.org>, linux-kernel@...r.kernel.org, 
	linux-pm@...r.kernel.org
Subject: Re: [PATCH v2 14/19] mm, swap: sanitize swap entry management workflow

On Mon, Nov 17, 2025 at 7:23 PM kernel test robot <lkp@...el.com> wrote:
>
> Hi Kairui,
>
> kernel test robot noticed the following build errors:
>
> [auto build test ERROR on 41218ede767f6b218185af65ce919d0cade75f6b]
>
> url:    https://github.com/intel-lab-lkp/linux/commits/Kairui-Song/mm-swap-rename-__read_swap_cache_async-to-swap_cache_alloc_folio/20251117-021532
> base:   41218ede767f6b218185af65ce919d0cade75f6b
> patch link:    https://lore.kernel.org/r/20251117-swap-table-p2-v2-14-37730e6ea6d5%40tencent.com
> patch subject: [PATCH v2 14/19] mm, swap: sanitize swap entry management workflow
> config: s390-defconfig (https://download.01.org/0day-ci/archive/20251117/202511171942.psG9jTRx-lkp@intel.com/config)
> compiler: clang version 22.0.0git (https://github.com/llvm/llvm-project 0bba1e76581bad04e7d7f09f5115ae5e2989e0d9)
> reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20251117/202511171942.psG9jTRx-lkp@intel.com/reproduce)
>
> If you fix the issue in a separate patch/commit (i.e. not just a new version of
> the same patch/commit), kindly add following tags
> | Reported-by: kernel test robot <lkp@...el.com>
> | Closes: https://lore.kernel.org/oe-kbuild-all/202511171942.psG9jTRx-lkp@intel.com/
>
> All errors (new ones prefixed by >>):
>
> >> arch/s390/mm/gmap_helpers.c:35:2: error: call to undeclared function 'free_swap_and_cache'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
>       35 |         free_swap_and_cache(entry);
>          |         ^
>    arch/s390/mm/gmap_helpers.c:35:2: note: did you mean 'free_swap_cache'?
>    include/linux/swap.h:435:6: note: 'free_swap_cache' declared here
>      435 | void free_swap_cache(struct folio *folio);
>          |      ^
>    1 error generated.
>
>
> vim +/free_swap_and_cache +35 arch/s390/mm/gmap_helpers.c
>
> 200197908dc4af Claudio Imbrenda 2025-05-28  19
> 200197908dc4af Claudio Imbrenda 2025-05-28  20  /**
> 6539cf8c98a8cc Lorenzo Stoakes  2025-11-10  21   * ptep_zap_softleaf_entry() - discard a software leaf entry.
> 200197908dc4af Claudio Imbrenda 2025-05-28  22   * @mm: the mm
> 6539cf8c98a8cc Lorenzo Stoakes  2025-11-10  23   * @entry: the software leaf entry that needs to be zapped
> 200197908dc4af Claudio Imbrenda 2025-05-28  24   *
> 6539cf8c98a8cc Lorenzo Stoakes  2025-11-10  25   * Discards the given software leaf entry. If the leaf entry was an actual
> 6539cf8c98a8cc Lorenzo Stoakes  2025-11-10  26   * swap entry (and not a migration entry, for example), the actual swapped
> 200197908dc4af Claudio Imbrenda 2025-05-28  27   * page is also discarded from swap.
> 200197908dc4af Claudio Imbrenda 2025-05-28  28   */
> 6539cf8c98a8cc Lorenzo Stoakes  2025-11-10  29  static void ptep_zap_softleaf_entry(struct mm_struct *mm, softleaf_t entry)
> 200197908dc4af Claudio Imbrenda 2025-05-28  30  {
> 6539cf8c98a8cc Lorenzo Stoakes  2025-11-10  31          if (softleaf_is_swap(entry))
> 200197908dc4af Claudio Imbrenda 2025-05-28  32                  dec_mm_counter(mm, MM_SWAPENTS);
> 6539cf8c98a8cc Lorenzo Stoakes  2025-11-10  33          else if (softleaf_is_migration(entry))
> 6539cf8c98a8cc Lorenzo Stoakes  2025-11-10  34                  dec_mm_counter(mm, mm_counter(softleaf_to_folio(entry)));
> 200197908dc4af Claudio Imbrenda 2025-05-28 @35          free_swap_and_cache(entry);
> 200197908dc4af Claudio Imbrenda 2025-05-28  36  }
> 200197908dc4af Claudio Imbrenda 2025-05-28  37

Ops, not sure why this callsite was missed during the renaming
conversion, probably lost it during a rebase as there are some
conflicts here. This should fix it:

diff --git a/arch/s390/mm/gmap_helpers.c b/arch/s390/mm/gmap_helpers.c
index 549f14ad08af..c3f56a096e8c 100644
--- a/arch/s390/mm/gmap_helpers.c
+++ b/arch/s390/mm/gmap_helpers.c
@@ -32,7 +32,7 @@ static void ptep_zap_softleaf_entry(struct mm_struct
*mm, softleaf_t entry)
                dec_mm_counter(mm, MM_SWAPENTS);
        else if (softleaf_is_migration(entry))
                dec_mm_counter(mm, mm_counter(softleaf_to_folio(entry)));
-       free_swap_and_cache(entry);
+       swap_put_entries_direct(entry, 1);
 }

Will include it in the next update.