On Mon, Nov 10, 2025 at 04:56:37PM -0500, Zi Yan wrote: > On 10 Nov 2025, at 16:16, Lorenzo Stoakes wrote: > > > 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 > > So softleaf_from_pte() returns softleaf_mk_none() instead and causes the > issue?
Yup :) fun! It's kinda crazy that on x86-64 at least we _intentionally_ generate an invalid swap entry but there we go. > > > + * this manually. > > + */ > > This comment is not aligned, in case you plan to send this patch as is. :) Lol ugh, well I've split out this fix with fixes for all other raised points and plan to send a v3 of that series to make life easier. There's a bunch of conflicts that arise from the changes so that's easier for everyone. > > > + 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 > > This fix looks good to me. Thanks. Thanks! > > Best Regards, > Yan, Zi Cheers, Lorenzo
