github-mirror/linux
1
0
Fork 0
mirror of https://github.com/torvalds/linux.git synced 2026-11-07 06:17:02 +01:00
Code Issues Actions Packages Projects Releases Wiki Activity Graph

mm/hugetlb: tolerate uffd bits set without uffd for PROT_NONE PTEs

Browse Source 
The whole uffd handling when a VMA is unregistered from UFFD is shaky:
there are still some scenarios where we might have stale uffd PTE bits
in VMAs no longer registered for UFFD, which confuses other code.

Let's just tolerate that for now and simply clear the PTE bit. Add a
TODO to really clean up any uffd leftovers when unregistering a VMA from
userfaultfd.

The handling is now more similar to what we have in handle_pte_fault().

Link: https://lore.kernel.org/20261015-urgent_fixes-v1-7-42796911043b@kernel.org
Fixes: 2d427bb016 ("mm/userfaultfd: add RWP fault delivery and expose UFFDIO_REGISTER_MODE_RWP")
Signed-off-by: David Hildenbrand (Arm) <david@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>
Reviewed-by: Lance Yang <lance.yang@linux.dev>
Acked-by: Kiryl Shutsemau (Meta) <kas@kernel.org>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Jann Horn <jannh@google.com>
Cc: Pedro Falcato <pfalcato@suse.de>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Naoya Horiguchi <nao.horiguchi@gmail.com>
Cc: Adam Litke <agl@us.ibm.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Rik van Riel <riel@surriel.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Josef Bacik <josef@toxicpanda.com>
Cc: <stable@vger.kernel.org>
This commit is contained in:
David Hildenbrand (Arm) 2026-10-15 18:07:13 +02:00 committed by Andrew Morton
parent f61e1cf15f
commit 811777d820
1 changed files with 6 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
mm/hugetlb.c
View File

@ -6169,16 +6169,20 @@ vm_fault_t hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma,
* NUMA hinting), so let normal hugetlb fault handling proceed.
*/
if (pte_protnone(vmf.orig_pte) && vma_is_accessible(vma) &&
userfaultfd_rwp(vma) && huge_pte_uffd(vmf.orig_pte)) {
huge_pte_uffd(vmf.orig_pte)) {
spinlock_t *ptl;
pte_t pte;
/* Sync: drop hugetlb locks before blocking in handle_userfault() */
if (!userfaultfd_rwp_async(vma))
if (userfaultfd_rwp(vma) && !userfaultfd_rwp_async(vma))
return hugetlb_handle_userfault(&vmf, mapping, VM_UFFD_RWP);
ptl = huge_pte_lock(h, mm, vmf.pte);
pte = huge_ptep_get(mm, vmf.address, vmf.pte);
/*
* TODO: fix all cases where uffd PTE bits remain in VMAs that
* are no longer registered with uffd.
*/
if (pte_protnone(pte) && huge_pte_uffd(pte)) {
unsigned int shift = huge_page_shift(h);