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authorDavid Hildenbrand <david@redhat.com>2024-06-05 11:17:10 +0200
committerAndrew Morton <akpm@linux-foundation.org>2024-06-15 10:43:05 -0700
commit384a746bb55960aa5ffb3a67de08f11fc2f51042 (patch)
tree9ccb04eb8cff6811cfd609be1deb332082e158f1 /mm/memory.c
parent8bb592c2eca8fd2bc06db7d80b38da18da4a2f43 (diff)
Revert "mm: init_mlocked_on_free_v3"
There was insufficient review and no agreement that this is the right approach. There are serious flaws with the implementation that make processes using mlock() not even work with simple fork() [1] and we get reliable crashes when rebooting. Further, simply because we might be unmapping a single PTE of a large mlocked folio, we shouldn't zero out the whole folio. ... especially because the code can also *corrupt* urelated memory because kernel_init_pages(page, folio_nr_pages(folio)); Could end up writing outside of the actual folio if we work with a tail page. Let's revert it. Once there is agreement that this is the right approach, the issues were fixed and there was reasonable review and proper testing, we can consider it again. [1] https://lkml.kernel.org/r/4da9da2f-73e4-45fd-b62f-a8a513314057@redhat.com Link: https://lkml.kernel.org/r/20240605091710.38961-1-david@redhat.com Fixes: ba42b524a040 ("mm: init_mlocked_on_free_v3") Signed-off-by: David Hildenbrand <david@redhat.com> Reported-by: David Wang <00107082@163.com> Closes: https://lore.kernel.org/lkml/20240528151340.4282-1-00107082@163.com/ Reported-by: Lance Yang <ioworker0@gmail.com> Closes: https://lkml.kernel.org/r/20240601140917.43562-1-ioworker0@gmail.com Acked-by: Lance Yang <ioworker0@gmail.com> Cc: York Jasper Niebuhr <yjnworkstation@gmail.com> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Kees Cook <keescook@chromium.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm/memory.c')
-rw-r--r--mm/memory.c6
1 files changed, 0 insertions, 6 deletions
diff --git a/mm/memory.c b/mm/memory.c
index 0f47a533014e..2bc8032a30a2 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1507,12 +1507,6 @@ static __always_inline void zap_present_folio_ptes(struct mmu_gather *tlb,
if (unlikely(folio_mapcount(folio) < 0))
print_bad_pte(vma, addr, ptent, page);
}
-
- if (want_init_mlocked_on_free() && folio_test_mlocked(folio) &&
- !delay_rmap && folio_test_anon(folio)) {
- kernel_init_pages(page, folio_nr_pages(folio));
- }
-
if (unlikely(__tlb_remove_folio_pages(tlb, page, nr, delay_rmap))) {
*force_flush = true;
*force_break = true;