arm64: mte: Do not warn if the page is already tagged in copy_highpage()

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[ Upstream commit b98c94eed4 ]

The arm64 copy_highpage() assumes that the destination page is newly
allocated and not MTE-tagged (PG_mte_tagged unset) and warns
accordingly. However, following commit 060913999d ("mm: migrate:
support poisoned recover from migrate folio"), folio_mc_copy() is called
before __folio_migrate_mapping(). If the latter fails (-EAGAIN), the
copy will be done again to the same destination page. Since
copy_highpage() already set the PG_mte_tagged flag, this second copy
will warn.

Replace the WARN_ON_ONCE(page already tagged) in the arm64
copy_highpage() with a comment.

Reported-by: syzbot+d1974fc28545a3e6218b@syzkaller.appspotmail.com
Link: https://lore.kernel.org/r/68dda1ae.a00a0220.102ee.0065.GAE@google.com
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: Will Deacon <will@kernel.org>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: stable@vger.kernel.org # 6.12.x
Reviewed-by: Yang Shi <yang@os.amperecomputing.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
[ omitted hugetlb MTE changes ]
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

...

This commit is contained in:

Catalin Marinas 2025-10-26 14:05:45 -04:00 • committed by Greg Kroah-Hartman

parent 1a1b13ef21

commit 5ff5765a1f

1 changed files with 7 additions and 2 deletions

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arch/arm64/mm/copypage.c

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