Re: [PATCH AUTOSEL 7.0-6.12] erofs: ensure all folios are managed in erofs_try_to_free_all_cached_folios()

[Gao Xiang]

On 2026/4/20 21:19, Sasha Levin wrote:
> From: Zhan Xusheng <zhanxusheng@xxxxxxxxxx>
>
> [ Upstream commit 5de6951fedb29700ace53b283ccb951c8f712d12 ]
>
> folio_trylock() in erofs_try_to_free_all_cached_folios() may
> successfully acquire the folio lock, but the subsequent check
> for erofs_folio_is_managed() can skip unlocking when the folio
> is not managed by EROFS.
>
> As Gao Xiang pointed out, this condition should not happen in
> practice because compressed_bvecs[] only holds valid cached folios
> at this point — any non-managed folio would have already been
> detached by z_erofs_cache_release_folio() under folio lock.
>
> Fix this by adding DBG_BUGON() to catch unexpected folios
> and ensure folio_unlock() is always called.
>
> Suggested-by: Gao Xiang <hsiangkao@xxxxxxxxxxxxxxxxx>
> Signed-off-by: Zhan Xusheng <zhanxusheng@xxxxxxxxxx>
> Reviewed-by: Gao Xiang <hsiangkao@xxxxxxxxxxxxxxxxx>
> Reviewed-by: Chunhai Guo <guochunhai@xxxxxxxx>
> Signed-off-by: Gao Xiang <hsiangkao@xxxxxxxxxxxxxxxxx>
> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
> ---
>
> LLM Generated explanations, may be completely bogus:
>
> Now I have a complete picture. Let me compile my analysis.

This is NOT a bugfix, but I don't mind if such random
patch backports to stable kernels.

Thanks,
Gao Xiang