On 7/7/25 07:27, Lorenzo Stoakes wrote:
Separate out the uffd bits so it clear's what's happening.
Don't bother setting vrm->mmap_locked after unlocking, because after this we are done anyway.
The only time we drop the mmap lock is on VMA shrink, at which point vrm->new_len will be < vrm->old_len and the operation will not be performed anyway, so move this code out of the if (vrm->mmap_locked) block.
All addresses returned by mremap() are page-aligned, so the offset_in_page() check on ret seems only to be incorrectly trying to detect
"incorrectly" to me implies there's a bug. But AFAIU there's not, so maybe e.g. "inappropriately"?
whether an error occurred - explicitly check for this.
No functional change intended.
Signed-off-by: Lorenzo Stoakes lorenzo.stoakes@oracle.com
Reviewed-by: Vlastimil Babka vbabka@suse.cz
Just a nit:
mm/mremap.c | 22 +++++++++++++--------- 1 file changed, 13 insertions(+), 9 deletions(-)
diff --git a/mm/mremap.c b/mm/mremap.c index 60eb0ac8634b..660bdb75e2f9 100644 --- a/mm/mremap.c +++ b/mm/mremap.c @@ -1729,6 +1729,15 @@ static int check_prep_vma(struct vma_remap_struct *vrm) return 0; } +static void notify_uffd(struct vma_remap_struct *vrm, unsigned long ret)
"ret" not "res"? :) Or actually why not name it for what it is, mremap_userfaultfd_complete() names the parameter "to". Maybe to_addr or new_addr?
+{
- struct mm_struct *mm = current->mm;
- userfaultfd_unmap_complete(mm, vrm->uf_unmap_early);
- mremap_userfaultfd_complete(vrm->uf, vrm->addr, ret, vrm->old_len);
- userfaultfd_unmap_complete(mm, vrm->uf_unmap);
+}
static unsigned long do_mremap(struct vma_remap_struct *vrm) { struct mm_struct *mm = current->mm; @@ -1754,18 +1763,13 @@ static unsigned long do_mremap(struct vma_remap_struct *vrm) res = vrm_implies_new_addr(vrm) ? mremap_to(vrm) : mremap_at(vrm); out:
- if (vrm->mmap_locked) {
- if (vrm->mmap_locked) mmap_write_unlock(mm);
vrm->mmap_locked = false;if (!offset_in_page(res) && vrm->mlocked && vrm->new_len > vrm->old_len)mm_populate(vrm->new_addr + vrm->old_len, vrm->delta);- }
- userfaultfd_unmap_complete(mm, vrm->uf_unmap_early);
- mremap_userfaultfd_complete(vrm->uf, vrm->addr, res, vrm->old_len);
- userfaultfd_unmap_complete(mm, vrm->uf_unmap);
- if (!IS_ERR_VALUE(res) && vrm->mlocked && vrm->new_len > vrm->old_len)
mm_populate(vrm->new_addr + vrm->old_len, vrm->delta);
- notify_uffd(vrm, res); return res;
}