Re: [PATCH] mm: filemap: correct the comment about VM_FAULT_RETRY
From: Song Liu
Date: Tue May 14 2019 - 19:42:08 EST
On Thu, Apr 25, 2019 at 4:22 PM Yang Shi <yang.shi@xxxxxxxxxxxxxxxxx> wrote:
> The commit 6b4c9f446981 ("filemap: drop the mmap_sem for all blocking
> operations") changed when mmap_sem is dropped during filemap page fault
> and when returning VM_FAULT_RETRY.
> Correct the comment to reflect the change.
> Cc: Josef Bacik <josef@xxxxxxxxxxxxxx>
> Signed-off-by: Yang Shi <yang.shi@xxxxxxxxxxxxxxxxx>
Looks good to me!
Acked-by: Song Liu <songliubraving@xxxxxx>
> mm/filemap.c | 6 ++----
> 1 file changed, 2 insertions(+), 4 deletions(-)
> diff --git a/mm/filemap.c b/mm/filemap.c
> index d78f577..f0d6250 100644
> --- a/mm/filemap.c
> +++ b/mm/filemap.c
> @@ -2545,10 +2545,8 @@ static struct file *do_async_mmap_readahead(struct vm_fault *vmf,
> * vma->vm_mm->mmap_sem must be held on entry.
> - * If our return value has VM_FAULT_RETRY set, it's because
> - * lock_page_or_retry() returned 0.
> - * The mmap_sem has usually been released in this case.
> - * See __lock_page_or_retry() for the exception.
> + * If our return value has VM_FAULT_RETRY set, it's because the mmap_sem
> + * may be dropped before doing I/O or by lock_page_maybe_drop_mmap().
> * If our return value does not have VM_FAULT_RETRY set, the mmap_sem
> * has not been released.