The patch titled Subject: mm/mremap: honour writable bit in mremap pte batching has been added to the -mm mm-hotfixes-unstable branch. Its filename is mm-mremap-honour-writable-bit-in-mremap-pte-batching.patch
This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches...
This patch will later appear in the mm-hotfixes-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------ From: Dev Jain dev.jain@arm.com Subject: mm/mremap: honour writable bit in mremap pte batching Date: Tue, 28 Oct 2025 12:09:52 +0530
Currently mremap folio pte batch ignores the writable bit during figuring out a set of similar ptes mapping the same folio. Suppose that the first pte of the batch is writable while the others are not - set_ptes will end up setting the writable bit on the other ptes, which is a violation of mremap semantics. Therefore, use FPB_RESPECT_WRITE to check the writable bit while determining the pte batch.
Link: https://lkml.kernel.org/r/20251028063952.90313-1-dev.jain@arm.com Signed-off-by: Dev Jain dev.jain@arm.com Fixes: f822a9a81a31 ("mm: optimize mremap() by PTE batching") Reported-by: David Hildenbrand david@redhat.com Debugged-by: David Hildenbrand david@redhat.com Acked-by: David Hildenbrand david@redhat.com Acked-by: Pedro Falcato pfalcato@suse.de Reviewed-by: Lorenzo Stoakes lorenzo.stoakes@oracle.com Cc: Barry Song baohua@kernel.org Cc: Jann Horn jannh@google.com Cc: Liam Howlett liam.howlett@oracle.com Cc: Vlastimil Babka vbabka@suse.cz Cc: stable@vger.kernel.org [6.17+] Signed-off-by: Andrew Morton akpm@linux-foundation.org ---
mm/mremap.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/mm/mremap.c~mm-mremap-honour-writable-bit-in-mremap-pte-batching +++ a/mm/mremap.c @@ -187,7 +187,7 @@ static int mremap_folio_pte_batch(struct if (!folio || !folio_test_large(folio)) return 1;
- return folio_pte_batch(folio, ptep, pte, max_nr); + return folio_pte_batch_flags(folio, NULL, ptep, &pte, max_nr, FPB_RESPECT_WRITE); }
static int move_ptes(struct pagetable_move_control *pmc, _
Patches currently in -mm which might be from dev.jain@arm.com are
mm-mremap-honour-writable-bit-in-mremap-pte-batching.patch