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 <[email protected]> Reviewed-by: Vlastimil Babka <[email protected]> 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; > } >
