diff options
| author | Peter Xu | 2024-06-05 17:21:46 -0400 |
|---|---|---|
| committer | Andrew Morton | 2024-06-15 10:43:04 -0700 |
| commit | 8bb592c2eca8fd2bc06db7d80b38da18da4a2f43 (patch) | |
| tree | 3ee30bea1274b725a6996d855c36163f66e7b0e7 | |
| parent | 8e5bd4eadd01ea0c47f3a1c798815849f813a700 (diff) | |
mm/page_table_check: fix crash on ZONE_DEVICE
Not all pages may apply to pgtable check. One example is ZONE_DEVICE
pages: they map PFNs directly, and they don't allocate page_ext at all
even if there's struct page around. One may reference
devm_memremap_pages().
When both ZONE_DEVICE and page-table-check enabled, then try to map some
dax memories, one can trigger kernel bug constantly now when the kernel
was trying to inject some pfn maps on the dax device:
kernel BUG at mm/page_table_check.c:55!
While it's pretty legal to use set_pxx_at() for ZONE_DEVICE pages for page
fault resolutions, skip all the checks if page_ext doesn't even exist in
pgtable checker, which applies to ZONE_DEVICE but maybe more.
Link: https://lkml.kernel.org/r/20240605212146.994486-1-peterx@redhat.com
Fixes: df4e817b7108 ("mm: page table check")
Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Alistair Popple <apopple@nvidia.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
| -rw-r--r-- | mm/page_table_check.c | 11 |
1 files changed, 10 insertions, 1 deletions
diff --git a/mm/page_table_check.c b/mm/page_table_check.c index 4169576bed72..509c6ef8de40 100644 --- a/mm/page_table_check.c +++ b/mm/page_table_check.c @@ -73,6 +73,9 @@ static void page_table_check_clear(unsigned long pfn, unsigned long pgcnt) page = pfn_to_page(pfn); page_ext = page_ext_get(page); + if (!page_ext) + return; + BUG_ON(PageSlab(page)); anon = PageAnon(page); @@ -110,6 +113,9 @@ static void page_table_check_set(unsigned long pfn, unsigned long pgcnt, page = pfn_to_page(pfn); page_ext = page_ext_get(page); + if (!page_ext) + return; + BUG_ON(PageSlab(page)); anon = PageAnon(page); @@ -140,7 +146,10 @@ void __page_table_check_zero(struct page *page, unsigned int order) BUG_ON(PageSlab(page)); page_ext = page_ext_get(page); - BUG_ON(!page_ext); + + if (!page_ext) + return; + for (i = 0; i < (1ul << order); i++) { struct page_table_check *ptc = get_page_table_check(page_ext); |