[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 at xiaomi.com>
> 
> [ 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 at linux.alibaba.com>
> Signed-off-by: Zhan Xusheng <zhanxusheng at xiaomi.com>
> Reviewed-by: Gao Xiang <hsiangkao at linux.alibaba.com>
> Reviewed-by: Chunhai Guo <guochunhai at vivo.com>
> Signed-off-by: Gao Xiang <hsiangkao at linux.alibaba.com>
> Signed-off-by: Sasha Levin <sashal at kernel.org>
> ---
> 
> 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