The patch titled
Subject: mm/khugepaged: fix invalid page access in release_pte_pages()
has been added to the -mm mm-unstable branch. Its filename is
mm-khugepaged-fix-invalid-page-access-in-release_pte_pages.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-khugepaged-fix-invalid-page-access-in-release_pte_pages.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: "Vishal Moola (Oracle)" <vishal.moola@xxxxxxxxx>
Subject: mm/khugepaged: fix invalid page access in release_pte_pages()
Date: Mon, 13 Feb 2023 13:43:24 -0800
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@xxxxxxxxxxx/
Link: https://lkml.kernel.org/r/20230213214324.34215-1-vishal.moola@xxxxxxxxx
Signed-off-by: Vishal Moola (Oracle) <vishal.moola@xxxxxxxxx>
Fixes: 9bdfeea46f49 ("mm/khugepaged: convert release_pte_pages() to use folios")
Reported-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
Debugged-by: Alexandre Ghiti <alex@xxxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
--- a/mm/khugepaged.c~mm-khugepaged-fix-invalid-page-access-in-release_pte_pages
+++ a/mm/khugepaged.c
@@ -511,11 +511,17 @@ static void release_pte_pages(pte_t *pte
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) {
_
Patches currently in -mm which might be from vishal.moola@xxxxxxxxx are
mm-khugepaged-fix-invalid-page-access-in-release_pte_pages.patch
mm-add-folio_estimated_sharers.patch
mm-mempolicy-convert-queue_pages_pmd-to-queue_folios_pmd.patch
mm-mempolicy-convert-queue_pages_pte_range-to-queue_folios_pte_range.patch
mm-mempolicy-convert-queue_pages_hugetlb-to-queue_folios_hugetlb.patch
mm-mempolicy-convert-queue_pages_required-to-queue_folio_required.patch
mm-mempolicy-convert-migrate_page_add-to-migrate_folio_add.patch
mm-add-folio_get_nontail_page.patch
mm-migrate-add-folio_movable_ops.patch
mm-migrate-convert-isolate_movable_page-to-use-folios.patch
mm-migrate-convert-putback_movable_pages-to-use-folios.patch
