release_pte_pages() converts from a pfn to a folio by using pfn_folio().
If the pte is not mapped, pfn_folio() will result in undefined behavior
which ends up causing a kernel panic[1].
Only call pfn_folio() once we have validated that the pte is both valid
and mapped to fix the issue.
[1] https://lore.kernel.org/linux-mm/
ff300770-afe9-908d-23ed-
d23e0796e899@samsung.com/
Link: https://lkml.kernel.org/r/20230213214324.34215-1-vishal.moola@gmail.com
Signed-off-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Fixes: 9bdfeea46f49 ("mm/khugepaged: convert release_pte_pages() to use folios")
Reported-by: Marek Szyprowski <m.szyprowski@samsung.com>
Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
Debugged-by: Alexandre Ghiti <alex@ghiti.fr>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
while (--_pte >= pte) {
pte_t pteval = *_pte;
+ unsigned long pfn;
- folio = pfn_folio(pte_pfn(pteval));
- if (!pte_none(pteval) && !is_zero_pfn(pte_pfn(pteval)) &&
- !folio_test_large(folio))
- release_pte_folio(folio);
+ if (pte_none(pteval))
+ continue;
+ pfn = pte_pfn(pteval);
+ if (is_zero_pfn(pfn))
+ continue;
+ folio = pfn_folio(pfn);
+ if (folio_test_large(folio))
+ continue;
+ release_pte_folio(folio);
}
list_for_each_entry_safe(folio, tmp, compound_pagelist, lru) {