OK ignore the past mail, I have managed to repro this locally and have a fix.
Turns out the swap code is doing something quite insane... I will send fix-patches to the series shortly. Meanwhile I attach fix-patch! :) Cheers, Lorenzo ----8<---- >From c705fd85a806f53017df31e6b072c4bfa839e3a2 Mon Sep 17 00:00:00 2001 From: Lorenzo Stoakes <[email protected]> Date: Mon, 10 Nov 2025 21:11:52 +0000 Subject: [PATCH] fix Signed-off-by: Lorenzo Stoakes <[email protected]> --- include/linux/leafops.h | 4 ++-- mm/swapfile.c | 12 ++++++++++-- 2 files changed, 12 insertions(+), 4 deletions(-) diff --git a/include/linux/leafops.h b/include/linux/leafops.h index a464a7e08c76..c4cd36760ea0 100644 --- a/include/linux/leafops.h +++ b/include/linux/leafops.h @@ -56,7 +56,7 @@ static inline softleaf_t softleaf_from_pte(pte_t pte) { softleaf_t arch_entry; - if (pte_present(pte)) + if (pte_present(pte) || pte_none(pte)) return softleaf_mk_none(); pte = pte_swp_clear_flags(pte); @@ -95,7 +95,7 @@ static inline softleaf_t softleaf_from_pmd(pmd_t pmd) { softleaf_t arch_entry; - if (pmd_present(pmd)) + if (pmd_present(pmd) || pmd_none(pmd)) return softleaf_mk_none(); if (pmd_swp_soft_dirty(pmd)) diff --git a/mm/swapfile.c b/mm/swapfile.c index fd23d9f7ae10..f0dcf261f652 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -3202,9 +3202,17 @@ static int claim_swapfile(struct swap_info_struct *si, struct inode *inode) */ unsigned long generic_max_swapfile_size(void) { - const softleaf_t entry = swp_entry(0, ~0UL); + softleaf_t entry = swp_entry(0, ~0UL); + const pte_t pte = softleaf_to_pte(entry); - return swp_offset(softleaf_from_pte(softleaf_to_pte(entry))) + 1; + /* + * Since the PTE can be an invalid swap entry (i.e. the none PTE), we do + * this manually. + */ + entry = __pte_to_swp_entry(pte); + entry = swp_entry(__swp_type(entry), __swp_offset(entry)); + + return swp_offset(entry) + 1; } /* Can be overridden by an architecture for additional checks. */ -- 2.51.0
