diff options
| author | Mike Kravetz <mike.kravetz@oracle.com> | 2023-01-26 14:27:21 -0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2023-02-14 19:17:56 +0100 |
| commit | 2e4dd07fda7ac207bd5ec7065f265265c0279279 (patch) | |
| tree | 306e11f09cc42bafa9d5923447ae177b0ee5973d /mm | |
| parent | 072e7412e857f464aeb263ae462d939d68dfa95b (diff) | |
| download | linux-2e4dd07fda7ac207bd5ec7065f265265c0279279.tar.gz linux-2e4dd07fda7ac207bd5ec7065f265265c0279279.tar.bz2 linux-2e4dd07fda7ac207bd5ec7065f265265c0279279.zip | |
migrate: hugetlb: check for hugetlb shared PMD in node migration
[ Upstream commit 73bdf65ea74857d7fb2ec3067a3cec0e261b1462 ]
migrate_pages/mempolicy semantics state that CAP_SYS_NICE is required to
move pages shared with another process to a different node. page_mapcount
> 1 is being used to determine if a hugetlb page is shared. However, a
hugetlb page will have a mapcount of 1 if mapped by multiple processes via
a shared PMD. As a result, hugetlb pages shared by multiple processes and
mapped with a shared PMD can be moved by a process without CAP_SYS_NICE.
To fix, check for a shared PMD if mapcount is 1. If a shared PMD is found
consider the page shared.
Link: https://lkml.kernel.org/r/20230126222721.222195-3-mike.kravetz@oracle.com
Fixes: e2d8cf405525 ("migrate: add hugepage migration code to migrate_pages()")
Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
Acked-by: Peter Xu <peterx@redhat.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: James Houghton <jthoughton@google.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Naoya Horiguchi <naoya.horiguchi@linux.dev>
Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Cc: Yang Shi <shy828301@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/mempolicy.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/mm/mempolicy.c b/mm/mempolicy.c index 8687781b41c9..818753635e42 100644 --- a/mm/mempolicy.c +++ b/mm/mempolicy.c @@ -603,7 +603,8 @@ static int queue_pages_hugetlb(pte_t *pte, unsigned long hmask, /* With MPOL_MF_MOVE, we migrate only unshared hugepage. */ if (flags & (MPOL_MF_MOVE_ALL) || - (flags & MPOL_MF_MOVE && page_mapcount(page) == 1)) { + (flags & MPOL_MF_MOVE && page_mapcount(page) == 1 && + !hugetlb_pmd_shared(pte))) { if (isolate_hugetlb(page, qp->pagelist) && (flags & MPOL_MF_STRICT)) /* |