On Fri, Oct 6, 2023 at 12:53 PM Matthew Wilcox (Oracle)
<willy@xxxxxxxxxxxxx> wrote:
>
> Drop the VMA lock instead of the mmap_lock if that's the one which
> is held.
>
> Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Reviewed-by: Suren Baghdasaryan <surenb@xxxxxxxxxx>
> ---
> mm/filemap.c | 13 +++++++------
> 1 file changed, 7 insertions(+), 6 deletions(-)
>
> diff --git a/mm/filemap.c b/mm/filemap.c
> index 9481ffaf24e6..a598872d62cc 100644
> --- a/mm/filemap.c
> +++ b/mm/filemap.c
> @@ -3104,7 +3104,7 @@ static int lock_folio_maybe_drop_mmap(struct vm_fault *vmf, struct folio *folio,
>
> /*
> * NOTE! This will make us return with VM_FAULT_RETRY, but with
> - * the mmap_lock still held. That's how FAULT_FLAG_RETRY_NOWAIT
> + * the fault lock still held. That's how FAULT_FLAG_RETRY_NOWAIT
> * is supposed to work. We have way too many special cases..
> */
> if (vmf->flags & FAULT_FLAG_RETRY_NOWAIT)
> @@ -3114,13 +3114,14 @@ static int lock_folio_maybe_drop_mmap(struct vm_fault *vmf, struct folio *folio,
> if (vmf->flags & FAULT_FLAG_KILLABLE) {
> if (__folio_lock_killable(folio)) {
> /*
> - * We didn't have the right flags to drop the mmap_lock,
> - * but all fault_handlers only check for fatal signals
> - * if we return VM_FAULT_RETRY, so we need to drop the
> - * mmap_lock here and return 0 if we don't have a fpin.
> + * We didn't have the right flags to drop the
> + * fault lock, but all fault_handlers only check
> + * for fatal signals if we return VM_FAULT_RETRY,
> + * so we need to drop the fault lock here and
> + * return 0 if we don't have a fpin.
> */
> if (*fpin == NULL)
> - mmap_read_unlock(vmf->vma->vm_mm);
> + release_fault_lock(vmf);
> return 0;
> }
> } else
> --
> 2.40.1
>
