The quilt patch titled Subject: mm/filemap: fix filemap_get_folios_contig THP panic has been removed from the -mm tree. Its filename was mm-filemap-fix-filemap_get_folios_contig-thp-panic.patch

This patch was dropped because it was merged into the mm-hotfixes-stable branch of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

------------------------------------------------------ From: Steve Sistare steven.sistare@oracle.com Subject: mm/filemap: fix filemap_get_folios_contig THP panic Date: Tue, 3 Sep 2024 07:25:17 -0700

Patch series "memfd-pin huge page fixes".

Fix multiple bugs that occur when using memfd_pin_folios with hugetlb pages and THP. The hugetlb bugs only bite when the page is not yet faulted in when memfd_pin_folios is called. The THP bug bites when the starting offset passed to memfd_pin_folios is not huge page aligned. See the commit messages for details.

This patch (of 5):

memfd_pin_folios on memory backed by THP panics if the requested start offset is not huge page aligned:

BUG: kernel NULL pointer dereference, address: 0000000000000036 RIP: 0010:filemap_get_folios_contig+0xdf/0x290 RSP: 0018:ffffc9002092fbe8 EFLAGS: 00010202 RAX: 0000000000000002 RBX: 0000000000000002 RCX: 0000000000000002

The fault occurs here, because xas_load returns a folio with value 2:

filemap_get_folios_contig() for (folio = xas_load(&xas); folio && xas.xa_index <= end; folio = xas_next(&xas)) { ... if (!folio_try_get(folio)) <-- BOOM

"2" is an xarray sibling entry. We get it because memfd_pin_folios does not round the indices passed to filemap_get_folios_contig to huge page boundaries for THP, so we load from the middle of a huge page range see a sibling. (It does round for hugetlbfs, at the is_file_hugepages test).

To fix, if the folio is a sibling, then return the next index as the starting point for the next call to filemap_get_folios_contig.

Link: https://lkml.kernel.org/r/1725373521-451395-1-git-send-email-steven.sistare@... Link: https://lkml.kernel.org/r/1725373521-451395-2-git-send-email-steven.sistare@... Fixes: 89c1905d9c14 ("mm/gup: introduce memfd_pin_folios() for pinning memfd folios") Signed-off-by: Steve Sistare steven.sistare@oracle.com Cc: David Hildenbrand david@redhat.com Cc: Jason Gunthorpe jgg@nvidia.com Cc: Matthew Wilcox willy@infradead.org Cc: Muchun Song muchun.song@linux.dev Cc: Peter Xu peterx@redhat.com Cc: Vivek Kasireddy vivek.kasireddy@intel.com Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org ---

mm/filemap.c | 4 ++++ 1 file changed, 4 insertions(+)

--- a/mm/filemap.c~mm-filemap-fix-filemap_get_folios_contig-thp-panic +++ a/mm/filemap.c @@ -2196,6 +2196,10 @@ unsigned filemap_get_folios_contig(struc if (xa_is_value(folio)) goto update_start;

+ /* If we landed in the middle of a THP, continue at its end. */ + if (xa_is_sibling(folio)) + goto update_start; + if (!folio_try_get(folio)) goto retry;

_

Patches currently in -mm which might be from steven.sistare@oracle.com are