From: Usama Arif migrate_vma_split_unmapped_folio() takes an extra reference via folio_get() before calling folio_split_unmapped(). On success, the split consumes this reference: __folio_freeze_and_split_unmapped() expects the +1 in its folio_ref_freeze() check, and distributes it across the resulting sub-folios via folio_ref_unfreeze(...+1), which are later balanced by folio_put() calls in __migrate_device_finalize(). If folio_split_unmapped() fails (e.g., unexpected pinning returns -EAGAIN), the function returns without calling folio_put(). The extra reference is never released. Add the missing folio_put() on the error path. Fixes: 4265d67e405a4 ("mm/migrate_device: add THP splitting during migration") Closes: https://lore.kernel.org/all/CAA1CXcDyqPPwf_-W7B+PFQtL8HdoJGCEqVsVxq7DhOUB=L4PQA@mail.gmail.com/ Reported-by: Nico Pache Signed-off-by: Usama Arif --- mm/migrate_device.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/mm/migrate_device.c b/mm/migrate_device.c index 0a8b31939640f..351ecd9065d13 100644 --- a/mm/migrate_device.c +++ b/mm/migrate_device.c @@ -917,8 +917,10 @@ static int migrate_vma_split_unmapped_folio(struct migrate_vma *migrate, folio_get(folio); split_huge_pmd_address(migrate->vma, addr, true); ret = folio_split_unmapped(folio, 0); - if (ret) + if (ret) { + folio_put(folio); return ret; + } migrate->src[idx] &= ~MIGRATE_PFN_COMPOUND; flags = migrate->src[idx] & ((1UL << MIGRATE_PFN_SHIFT) - 1); pfn = migrate->src[idx] >> MIGRATE_PFN_SHIFT; -- 2.47.3