diff options
| author | Liu Shixin <liushixin2@huawei.com> | 2025-01-22 14:11:51 +0800 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2025-04-01 15:14:43 -0700 |
| commit | a0a9f2180b90c7d5f7c85a77b359856f675cf760 (patch) | |
| tree | ab2a1f5a551137a60d30728600c47a2f2509d3a7 /mm | |
| parent | b98072af60a7ce19214c80f10a7daab924c69182 (diff) | |
mm: page_isolation: avoid calling folio_hstate() without hugetlb_lock
I found a NULL pointer dereference as followed:
BUG: kernel NULL pointer dereference, address: 0000000000000028
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 0 P4D 0
Oops: Oops: 0000 [#1] SMP PTI
CPU: 5 UID: 0 PID: 5964 Comm: sh Kdump: loaded Not tainted 6.13.0-dirty #20
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1.
RIP: 0010:has_unmovable_pages+0x184/0x360
...
Call Trace:
<TASK>
set_migratetype_isolate+0xd1/0x180
start_isolate_page_range+0xd2/0x170
alloc_contig_range_noprof+0x101/0x660
alloc_contig_pages_noprof+0x238/0x290
alloc_gigantic_folio.isra.0+0xb6/0x1f0
only_alloc_fresh_hugetlb_folio.isra.0+0xf/0x60
alloc_pool_huge_folio+0x80/0xf0
set_max_huge_pages+0x211/0x490
__nr_hugepages_store_common+0x5f/0xe0
nr_hugepages_store+0x77/0x80
kernfs_fop_write_iter+0x118/0x200
vfs_write+0x23c/0x3f0
ksys_write+0x62/0xe0
do_syscall_64+0x5b/0x170
entry_SYSCALL_64_after_hwframe+0x76/0x7e
As has_unmovable_pages() call folio_hstate() without hugetlb_lock, there
is a race to free the HugeTLB page between PageHuge() and folio_hstate().
There is no need to add hugetlb_lock here as the HugeTLB page can be freed
in lot of places. So it's enough to unfold folio_hstate() and add a check
to avoid NULL pointer dereference for hugepage_migration_supported().
Link: https://lkml.kernel.org/r/20250122061151.578768-1-liushixin2@huawei.com
Fixes: 464c7ffbcb16 ("mm/hugetlb: filter out hugetlb pages if HUGEPAGE migration is not supported.")
Signed-off-by: Liu Shixin <liushixin2@huawei.com>
Acked-by: David Hildenbrand <david@redhat.com>
Acked-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Kirill A. Shuemov <kirill.shutemov@linux.intel.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Nanyong Sun <sunnanyong@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/page_isolation.c | 9 |
1 files changed, 8 insertions, 1 deletions
diff --git a/mm/page_isolation.c b/mm/page_isolation.c index a051a29e95ad..b2fc5266e3d2 100644 --- a/mm/page_isolation.c +++ b/mm/page_isolation.c @@ -83,7 +83,14 @@ static struct page *has_unmovable_pages(unsigned long start_pfn, unsigned long e unsigned int skip_pages; if (PageHuge(page)) { - if (!hugepage_migration_supported(folio_hstate(folio))) + struct hstate *h; + + /* + * The huge page may be freed so can not + * use folio_hstate() directly. + */ + h = size_to_hstate(folio_size(folio)); + if (h && !hugepage_migration_supported(h)) return page; } else if (!folio_test_lru(folio) && !__folio_test_movable(folio)) { return page; |