On Thu, 2 Apr 2026 16:47:28 +0300 Mike Rapoport <[email protected]> wrote:
> > Drop the retry logic from mfill_atomic(). > > > > Signed-off-by: Mike Rapoport (Microsoft) <[email protected]> > > --- > > mm/userfaultfd.c | 24 ------------------------ > > 1 file changed, 24 deletions(-) > > After discussion with David Carlier about potential replacement of VMA in > mfill_copy_folio_retry(), I looked again in the code and realized that > after all the rebases I didn't remove the bit that temporarily prevented > returning ENOENT from __mfill_atomic_pte(). > > Andrew, can you please fold this into "userfaultfd: mfill_atomic(): remove > retry logic"? > > For a change it applies cleanly :) done. > commit 5173c8f4fd32f314907b3804217ef57d4e3a2220 > Author: Mike Rapoport (Microsoft) <[email protected]> > Date: Thu Apr 2 16:38:39 2026 +0300 > > userfaultfd: remove safety mesaure of not returning ENOENT from _copy s/mesaure/measure/ Was "_copy" intended? > > Signed-off-by: Mike Rapoport (Microsoft) <[email protected]> I instafolded this. End result: From: "Mike Rapoport (Microsoft)" <[email protected]> Subject: userfaultfd: mfill_atomic(): remove retry logic Date: Thu, 2 Apr 2026 07:11:52 +0300 Since __mfill_atomic_pte() handles the retry for both anonymous and shmem, there is no need to retry copying the date from the userspace in the loop in mfill_atomic(). Drop the retry logic from mfill_atomic(). [[email protected]: remove safety measure of not returning ENOENT from _copy] Link: https://lkml.kernel.org/r/[email protected] Link: https://lkml.kernel.org/r/[email protected] Signed-off-by: Mike Rapoport (Microsoft) <[email protected]> Cc: Andrea Arcangeli <[email protected]> Cc: Andrei Vagin <[email protected]> Cc: Axel Rasmussen <[email protected]> Cc: Baolin Wang <[email protected]> Cc: David Hildenbrand (Arm) <[email protected]> Cc: Harry Yoo <[email protected]> Cc: Harry Yoo (Oracle) <[email protected]> Cc: Hugh Dickins <[email protected]> Cc: James Houghton <[email protected]> Cc: Liam Howlett <[email protected]> Cc: Lorenzo Stoakes (Oracle) <[email protected]> Cc: Matthew Wilcox (Oracle) <[email protected]> Cc: Michal Hocko <[email protected]> Cc: Muchun Song <[email protected]> Cc: Nikita Kalyazin <[email protected]> Cc: Oscar Salvador <[email protected]> Cc: Paolo Bonzini <[email protected]> Cc: Peter Xu <[email protected]> Cc: Sean Christopherson <[email protected]> Cc: Shuah Khan <[email protected]> Cc: Suren Baghdasaryan <[email protected]> Cc: Vlastimil Babka <[email protected]> Signed-off-by: Andrew Morton <[email protected]> --- mm/userfaultfd.c | 27 --------------------------- 1 file changed, 27 deletions(-) --- a/mm/userfaultfd.c~userfaultfd-mfill_atomic-remove-retry-logic +++ a/mm/userfaultfd.c @@ -29,7 +29,6 @@ struct mfill_state { struct vm_area_struct *vma; unsigned long src_addr; unsigned long dst_addr; - struct folio *folio; pmd_t *pmd; }; @@ -531,9 +530,6 @@ err_filemap_remove: ops->filemap_remove(folio, state->vma); err_folio_put: folio_put(folio); - /* Don't return -ENOENT so that our caller won't retry */ - if (ret == -ENOENT) - ret = -EFAULT; return ret; } @@ -899,7 +895,6 @@ static __always_inline ssize_t mfill_ato VM_WARN_ON_ONCE(src_start + len <= src_start); VM_WARN_ON_ONCE(dst_start + len <= dst_start); -retry: err = mfill_get_vma(&state); if (err) goto out; @@ -926,26 +921,6 @@ retry: err = mfill_atomic_pte(&state); cond_resched(); - if (unlikely(err == -ENOENT)) { - void *kaddr; - - mfill_put_vma(&state); - VM_WARN_ON_ONCE(!state.folio); - - kaddr = kmap_local_folio(state.folio, 0); - err = copy_from_user(kaddr, - (const void __user *)state.src_addr, - PAGE_SIZE); - kunmap_local(kaddr); - if (unlikely(err)) { - err = -EFAULT; - goto out; - } - flush_dcache_folio(state.folio); - goto retry; - } else - VM_WARN_ON_ONCE(state.folio); - if (!err) { state.dst_addr += PAGE_SIZE; state.src_addr += PAGE_SIZE; @@ -960,8 +935,6 @@ retry: mfill_put_vma(&state); out: - if (state.folio) - folio_put(state.folio); VM_WARN_ON_ONCE(copied < 0); VM_WARN_ON_ONCE(err > 0); VM_WARN_ON_ONCE(!copied && !err); _
