Re: [PATCH] btrfs: fix missing folio_unlock in read_merkle_tree_page error path

[Hongling Zeng]

在 2026年08月17日 14:43, Qu Wenruo 写道:
> 在 2026/8/17 15:06, Hongling Zeng 写道:
> > filemap_add_folio() adds the folio to the page cache and leaves it 
> > locked.
> > If read_key_bytes() fails, the error path only calls folio_put() without
> > first unlocking the folio, leaving it permanently locked in the page 
> > cache.
> > This causes subsequent attempts to lock this folio to hang.
> >
> > Fix by adding folio_unlock() before folio_put() in the error handling 
> > path.
> >
> > Fixes: 06ed09351b67 ("btrfs: convert btrfs_read_merkle_tree_page() to 
> > use a folio")
> > Cc: stable@xxxxxxxxxxxxxxx
> > Assisted-by: Codex:gpt-5.5
> > Signed-off-by: Hongling Zeng <zenghongling@xxxxxxxxxx>
>
> A fix is already submitted and merged:
>
> https://lore.kernel.org/linux-btrfs/20260722025435.1493093-1-chenyichong@xxxxxxxxxxxxx/ 
>
>
> Next time let your agent to read the btrfs developer's note and check 
> if there is already a fix:
>
> https://btrfs.readthedocs.io/en/latest/dev/Developer-s-FAQ.html#development-phase-linux-next-for-next 
  Thanks for the feedback.

  I should have checked for existing fixes first.

  I will ensure to check git history and mailing lists before submitting
  future patches.

  Apologies for the duplicate submission.
> > ---
> >   fs/btrfs/verity.c | 1 +
> >   1 file changed, 1 insertion(+)
> >
> > diff --git a/fs/btrfs/verity.c b/fs/btrfs/verity.c
> > index 983365a73541..4431656140f8 100644
> > --- a/fs/btrfs/verity.c
> > +++ b/fs/btrfs/verity.c
> > @@ -753,6 +753,7 @@ static struct page 
> > *btrfs_read_merkle_tree_page(struct inode *inode,
> >       ret = read_key_bytes(BTRFS_I(inode), 
> > BTRFS_VERITY_MERKLE_ITEM_KEY, off,
> >                    folio_address(folio), PAGE_SIZE, folio);
> >       if (ret < 0) {
> > +        folio_unlock(folio);
> >           folio_put(folio);
> >           return ERR_PTR(ret);
> >       }