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| author | Catalin Marinas <catalin.marinas@arm.com> | 2025-10-26 14:05:45 -0400 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2025-10-29 14:09:02 +0100 |
| commit | 5ff5765a1fc526f07d3bbaedb061d970eb13bcf4 (patch) | |
| tree | cc0f9e42729d01bf0a152ba31ad85c7ff25182eb | |
| parent | 1a1b13ef21cb1741bdaff471ae265c3edcff91cf (diff) | |
| download | linux-5ff5765a1fc526f07d3bbaedb061d970eb13bcf4.tar.gz linux-5ff5765a1fc526f07d3bbaedb061d970eb13bcf4.tar.bz2 linux-5ff5765a1fc526f07d3bbaedb061d970eb13bcf4.zip | |
arm64: mte: Do not warn if the page is already tagged in copy_highpage()
[ Upstream commit b98c94eed4a975e0c80b7e90a649a46967376f58 ]
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 060913999d7a ("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>
| -rw-r--r-- | arch/arm64/mm/copypage.c | 9 |
1 files changed, 7 insertions, 2 deletions
diff --git a/arch/arm64/mm/copypage.c b/arch/arm64/mm/copypage.c index a7bb20055ce0..9e734d6314e0 100644 --- a/arch/arm64/mm/copypage.c +++ b/arch/arm64/mm/copypage.c @@ -25,8 +25,13 @@ void copy_highpage(struct page *to, struct page *from) page_kasan_tag_reset(to); if (system_supports_mte() && page_mte_tagged(from)) { - /* It's a new page, shouldn't have been tagged yet */ - WARN_ON_ONCE(!try_page_mte_tagging(to)); + /* + * Most of the time it's a new page that shouldn't have been + * tagged yet. However, folio migration can end up reusing the + * same page without untagging it. Ignore the warning if the + * page is already tagged. + */ + try_page_mte_tagging(to); mte_copy_page_tags(kto, kfrom); set_page_mte_tagged(to); } |