From 439b3fb0b01005e08e91578278475269215e9a7f Mon Sep 17 00:00:00 2001 From: Lorenzo Stoakes Date: Fri, 9 May 2025 13:13:35 +0100 Subject: [PATCH] mm: secretmem: convert to .mmap_prepare() hook Secretmem has a simple .mmap() hook which is easily converted to the new .mmap_prepare() callback. Importantly, it's a rare instance of an driver that manipulates a VMA which is mergeable (that is, not a VM_SPECIAL mapping) while also adjusting VMA flags which may adjust mergeability, meaning the retry merge logic might impact whether or not the VMA is merged. By using .mmap_prepare() there's no longer any need to retry the merge later as we can simply set the correct flags from the start. This change therefore allows us to remove the retry merge logic in a subsequent commit. Link: https://lkml.kernel.org/r/0f758474fa6a30197bdf25ba62f898a69d84eef3.1746792520.git.lorenzo.stoakes@oracle.com Signed-off-by: Lorenzo Stoakes Acked-by: Mike Rapoport (Microsoft) Reviewed-by: David Hildenbrand Reviewed-by: Vlastimil Babka Cc: Al Viro Cc: Christian Brauner Cc: Jan Kara Cc: Jann Horn Cc: Liam Howlett Cc: Matthew Wilcox (Oracle) Cc: Michal Hocko Cc: Suren Baghdasaryan Signed-off-by: Andrew Morton --- mm/secretmem.c | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-) diff --git a/mm/secretmem.c b/mm/secretmem.c index 1b0a214ee558..589b26c2d553 100644 --- a/mm/secretmem.c +++ b/mm/secretmem.c @@ -120,18 +120,18 @@ static int secretmem_release(struct inode *inode, struct file *file) return 0; } -static int secretmem_mmap(struct file *file, struct vm_area_struct *vma) +static int secretmem_mmap_prepare(struct vm_area_desc *desc) { - unsigned long len = vma->vm_end - vma->vm_start; + const unsigned long len = desc->end - desc->start; - if ((vma->vm_flags & (VM_SHARED | VM_MAYSHARE)) == 0) + if ((desc->vm_flags & (VM_SHARED | VM_MAYSHARE)) == 0) return -EINVAL; - if (!mlock_future_ok(vma->vm_mm, vma->vm_flags | VM_LOCKED, len)) + if (!mlock_future_ok(desc->mm, desc->vm_flags | VM_LOCKED, len)) return -EAGAIN; - vm_flags_set(vma, VM_LOCKED | VM_DONTDUMP); - vma->vm_ops = &secretmem_vm_ops; + desc->vm_flags |= VM_LOCKED | VM_DONTDUMP; + desc->vm_ops = &secretmem_vm_ops; return 0; } @@ -143,7 +143,7 @@ bool vma_is_secretmem(struct vm_area_struct *vma) static const struct file_operations secretmem_fops = { .release = secretmem_release, - .mmap = secretmem_mmap, + .mmap_prepare = secretmem_mmap_prepare, }; static int secretmem_migrate_folio(struct address_space *mapping, -- 2.50.1